Publications by authors named "Afsaneh Amirabadi"

28 Publications

  • Page 1 of 1

Usefulness of TI-scout images in the assessment of late gadolinium enhancement in children.

J Cardiovasc Magn Reson 2021 Mar 18;23(1):28. Epub 2021 Mar 18.

Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON, M5G1X8, Canada.

Background: Cardiovascular magnetic resonance (CMR) late gadolinium enhancement (LGE) requires identification of the normal myocardial nulling time using inversion time (TI)-scout imaging sequence. Although TI-scout images are not primarily used for myocardial assessment, they provide information regarding different signal recovery patterns of normal and abnormal myocardium facilitating identification of LGE in instances where standard LGE images alone are not diagnostic. We aimed to assess the diagnostic performance of TI-scout as compared to that of standard LGE images.

Methods: CMR studies with LGE imaging in 519 patients (345 males, 1-17 years) were reviewed to assess the diagnostic performance of LGE imaging in terms of the location of LGE and the pathologic entities. The diagnostic performance of the TI-scout and standard LGE imaging was classified into four categories: (1) equally diagnostic, (2) TI-scout superior to standard LGE, (3) standard LGE superior to TI-scout, and (4) complementary, by the consensus of the two observers.

Results: The study cohort consisted of 440 patients with negative LGE and 79 with evidence for LGE. For a negative diagnosis of LGE, TI-scout and standard LGE images were equally diagnostic in 75% of the cases and were complementary in 12%. For patients with LGE, TI-scout images were superior to standard LGE images in 52% of the cases and were complementary in 19%. The diagnostic performance of TI-scout images was superior to that of standard LGE images in all locations. TI-scout images were superior to standard LGE images in 11 of 12 (92%) cases with LGE involving the papillary muscles, in 7 /12 (58%) cases with subendocardial LGE, and in 4/7 (57%) cases with transmural LGE. TI-scout images were particularly useful assessing the presence and extent of LGE in hypertrophic cardiomyopathy (HCM). TI-scout was superior to standard LGE in 6/10 (60%) and was complementary in 3/10 (30%) of the positive cases with HCM.

Conclusions: TI-scout images enhance the diagnostic performance of LGE imaging in children.
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http://dx.doi.org/10.1186/s12968-021-00719-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7972209PMC
March 2021

Use of radial access sheaths for transfemoral neuroendovascular procedures in children.

Neuroradiology 2021 Apr 9;63(4):633-635. Epub 2021 Feb 9.

Divisions of Neuroradiology and Image Guided Therapy, Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, Toronto, ON, M5G 1X8, Canada.

Purpose: Pediatric neuroendovascular procedures require special considerations. Given small vessel sizes, risk for arterial injury must be weighed against use of larger devices, with the diameter of the sheath being a known association with arterial complications. We recently transitioned to using thin-walled radial sheaths for transfemoral angiography in children, given their lower profile. Here, we report on these sheaths' technical success and complications, comparing against a historical cohort where regular vascular sheaths were employed.

Methods: We retrospectively recorded patient and procedural data from 168 consecutive procedures from September 2017 to January 2019 when radial-specific sheaths were exclusively used at our tertiary pediatric hospital. These results were compared to data from September 2015 to January 2017, when regular vascular sheaths were exclusively used in 152 consecutive procedures. Statistical analysis was performed using unpaired t test or chi-square test, with p < 0.05 considered statistically significant.

Results: Patient characteristics (age, sex, weight) were not statistically different between the case and control group. No significant differences were found in the procedural data with the exception of heparin use which was higher in the radial-sheath cohort. There was a decrease in the rate of complications in the case group (1.2%) versus control group (2.6%), though not statistically different.

Conclusion: Radial-specific sheaths have numerous beneficial characteristics that make them well-suited to the pediatric population. In our study, we show that radial sheaths are equally effective and safe perioperatively. Follow-up research may show if radial sheaths used transfemorally decrease long-term complications such as limb-length discrepancy and mortality.
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http://dx.doi.org/10.1007/s00234-021-02664-4DOI Listing
April 2021

Diagnostic Performance of a Sonographic Volume and Solid Vascular Tissue Score (VSVTS) for Preoperative Risk Assessment of Pediatric and Adolescent Adnexal Masses.

J Pediatr Adolesc Gynecol 2020 Nov 30. Epub 2020 Nov 30.

Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada. Electronic address:

Study Objective: To evaluate the diagnostic performance of a Volume and Solid Vascular Tissue Score (VSVTS) for preoperative risk assessment of pediatric and adolescent adnexal masses.

Design: A retrospective cohort study comprised of all female individuals who presented with an adnexal mass that was managed surgically between April 2011 and March 2016.

Setting: The Hospital for Sick Children (Toronto, Ontario, Canada).

Participants: Female individuals 1-18 years of age who presented to a large tertiary pediatric hospital with an adnexal mass that was managed surgically.

Main Outcome Measures: Main outcome measures included diagnostic performance of the VSVTS for malignancy via sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+), negative likelihood ratio (LR-), and receiver operating characteristic area-under-the-curve (AUC) analysis.

Results: A total of 179 masses in 169 subjects were included. The malignancy rate was 10.6%. The AUC for the VSTVS was 0.919. A VSTVS cut-off value of 4 achieved a sensitivity of 79% (95% CI 0.54-0.93), specificity of 88% (95% CI 0.82-0.93), PPV of 0.44 (95% CI 0.33-0.56), NPV of 0.97 (95% CI 0.94-0.99), LR+ of 6.77 (95% CI 4.18-10.97), and LR- of 0.24 (95% CI 0.10-0.57).

Conclusions: A sonographic scoring system based on the volume and presence of solid vascular tissue improves PPV for preoperative risk stratification of adnexal masses in the pediatric and adolescent population compared to existing ultrasound-only approaches. Further prospective research is needed to determine how best to incorporate components of such scoring systems into clinical management algorithms.
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http://dx.doi.org/10.1016/j.jpag.2020.11.017DOI Listing
November 2020

Utility of sonography for identifying metastatic cervical adenopathy in children with differentiated thyroid carcinoma at presentation.

Pediatr Radiol 2021 Feb 8;51(2):273-281. Epub 2020 Oct 8.

Division of Endocrinology, Department of Pediatrics, Hospital for Sick Children, Toronto, ON, Canada.

Background: No study has evaluated the diagnostic accuracy of sonography for the depiction of metastatic cervical adenopathy in children with differentiated thyroid carcinoma at presentation or determined which sonographic features are most useful.

Objective: To evaluate the diagnostic accuracy of sonography for identifying metastatic cervical adenopathy in children with differentiated thyroid carcinoma at presentation and to determine the most useful sonographic features.

Materials And Methods: We evaluated cervical lymph node sonography and histology in children with proven thyroid carcinoma in a 10-year period. We excluded children in whom a preoperative sonogram was not available and those who did not have surgical resection of lymph nodes. We used histology as the gold standard. On sonography, we analyzed the size, shape, echotexture and vascularity of the lymph nodes and correlated these findings with the histology.

Results: We reviewed sonograms and histology of resected lymph nodes in 52 children and adolescents with proven differentiated thyroid carcinoma (33 females; ages 5-18 years, mean 13.2 years). Metastatic cervical lymph node disease was proved on histology in 33/52 (64%) of our patients at presentation. Sonographic findings correctly predicted whether the nodes were histologically involved with metastatic disease in 42/52 (81%). Sensitivity of sonography was 79%, specificity 84%, positive predictive value (PPV) 90%, negative predictive value (NPV) 70% and accuracy 81%. A significant association was seen between round shape (P=0.0002), abnormal echotexture (P≤0.0001) and vascularity (P≤0.0001), and abnormal lymph node histology. Importantly, in 11/26 (47%) patients with sonographic and histologically proven abnormal nodes, the nodes were normal in size and shape and the presence of metastatic involvement was recognized sonographically only on the basis of abnormal echogenicity and vascularity.

Conclusion: Sonography has a high accuracy, specificity and PPV for identifying metastatic cervical lymph node involvement in children with differentiated thyroid carcinoma at presentation. Most of the abnormal lymph nodes were round in shape and had abnormal echogenicity and vascularity. Importantly, this paper emphasizes that in children, nodes with histologically proven metastases from differentiated thyroid carcinoma can be normal in size and shape. In these patients the presence of metastatic involvement might be recognized sonographically only on the basis of abnormal echogenicity and vascularity.
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http://dx.doi.org/10.1007/s00247-020-04804-zDOI Listing
February 2021

Assessment of Needs in Children Suffering From Refractory Non-neurogenic Urinary and Fecal Incontinence and Their Caregivers' Needs and Attitudes Toward Alternative Therapies (SNM, TENS).

Front Pediatr 2020 9;8:558. Epub 2020 Sep 9.

Division of Urology, The Hospital for Sick Children, Toronto, ON, Canada.

Non-neurogenic urinary and fecal incontinence (UI, FI) affects approximately 6% of North American children with 1% of cases becoming refractory (nonresponsive to standard therapies). Incontinence has major potential long-term physiological and psychological implications for patients and their families. While Sacral Neuromodulation (SNM) and Transcutaneous Nerve Stimulation (TENS) are alternative therapies available for the treatment of refractory UI/FI, these are not approved for use in children in Canada. The present study assessed participants' perception of current treatments, incontinence burden, and attitudes toward novel therapies in a single pediatric institution. Multiple validated questionnaires including Dysfunctional Voiding Scoring System (DVSS), Bristol Stool Chart (BSC), Pediatric Incontinence measurement (PinQ), and Time-Driven Activity Based Costing were used to perform a needs assessment for patients with non-neurogenic refractory incontinence, and to determine patients' and caregivers' attitudes toward alternative therapies. 75% of patients and 89% of caregivers reported a moderate to severe impact of incontinence on QoL with diminished social interactions among the primary concerns. Caregivers were frustrated with current treatments and were open to trying alternative therapies (SNM and TENS), which, at least in the case of SNM, seems to be less expensive, possibly less burdensome and more effective than current surgical options. Pediatric refractory UI/FI has a large impact on patients' and caregivers' QoL and alternative therapies with the potential to improve QoL of patients and caregivers should be further investigated as a substitute for surgery.
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http://dx.doi.org/10.3389/fped.2020.00558DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7509042PMC
September 2020

The utility of post-biopsy ultrasonography in detecting complications after percutaneous liver biopsy in children.

Pediatr Radiol 2020 11 13;50(12):1717-1723. Epub 2020 Aug 13.

Department of Medical Imaging, The Hospital for Sick Children, 555 University Ave., Toronto, ON, M5G 1X8, Canada.

Background: Surveillance post image-guided percutaneous liver biopsy in children is variable.

Objective: The aim of this study was to assess the value of 4-6-h post-procedure ultrasonography (US) in detecting post-liver-biopsy hemorrhage.

Materials And Methods: This prospective study included pediatric patients who underwent US-guided percutaneous liver biopsies. All children had a US study obtained pre-procedure and one obtained 4-6 h post-procedure; US examinations were deemed positive if abnormalities were present. We also reviewed any subsequent imaging that was performed within 7 days (late imaging) at the discretion of the referring team. Changes in US findings (ΔUS) were graded by two radiologists using a descriptive non-validated scale (none, minimal, marked). Hemoglobin (Hb) levels were assessed pre-procedure and 4 h post-procedure. The diagnostic accuracy of US changes for detecting post-procedural hemorrhage was calculated based on a drop in Hb >1.5 g/dL or Hb >15% from baseline (ΔHb). We used a Kruskal-Wallis test to correlate the ΔHb with ΔUS. Association between late-imaging and post-procedure US findings was tested using a chi-square test. We included 224 biopsies.

Results: The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of post-procedure US in detecting post-procedure hemorrhage ranged 26.3-42.1%, 72.4-93.3%, 0.22-0.42, and 0.87-0.88, respectively. No significant association was seen between the ΔHb and sonographic findings (P=0.068). No significant difference was seen in the need for late imaging between children who did and those who did not have positive US findings (P=0.814).

Conclusion: The sensitivity and PPV of post-procedure US in detecting post-procedural hemorrhage are low. Our findings do not support routine post-procedure surveillance US.
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http://dx.doi.org/10.1007/s00247-020-04783-1DOI Listing
November 2020

Can Children Be Considered for Transradial Interventions?: Prospective Study of Sonographic Radial Artery Diameters.

Circ Cardiovasc Interv 2020 07 2;13(7):e009251. Epub 2020 Jul 2.

Department of Image Guided Therapy (A.A., W.H., S.B., A.A.D., K.B., P.M.), The Hospital for Sick Children, University of Toronto, ON, Canada.

Background: Transradial intervention is increasingly replacing approaches, due to lower access complications, cost, and improved patient satisfaction. There are limited supporting data in the pediatric literature, largely due to concerns regarding arterial size. The objective of this study was to measure radial artery diameters in children across all age groups, to establish reference ranges for clinical use.

Methods: This prospective study was carried out in children ≤18 years of age who underwent ultrasound for measuring radial artery diameters from November 2018 to November 2019. The cohort was divided into age groups: ≤2, 3 to 5, 6 to 8, 9 to 11, 12 to 14, 15 to 18 years, and into pre- and post-adolescent (≥12 years) groups.

Results: One hundred thirty-four children (M:F=63:71) were included, with bilateral measurements resulting in 268 data points. Mean age was 8.9±5.8 years (range, 29 days to 18 years), mean weight 37.2±27.5 kg (range, 1.7-149.1 kg). Mean-corrected radial artery diameter was 1.86±0.44 mm. There was no difference in arterial diameters between males and females (1.90±0.50 versus 1.81±0.53 mm; =0.73) or between right and left sides (1.87±0.46 versus 1.87±0.47, =0.98). There was a strong correlation of diameter with age (R=0.75; <0.00001) and weight (R=0.74; <0.00001). There was linear increase in arterial growth rates in early childhood, followed by plateauing to adult sizes in adolescents. Inter-reader agreement was 0.95.

Conclusions: We provide a reference range for radial artery diameters across childhood ages, which can be used for decision-making. This could be the basis for designing a trial of transradial intervention in children, to establish clinical safety and efficacy.
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http://dx.doi.org/10.1161/CIRCINTERVENTIONS.120.009251DOI Listing
July 2020

The role of MRA in pediatric sickle cell disease with normal transcranial Doppler imaging velocities.

J Stroke Cerebrovasc Dis 2020 Jul 10;29(7):104864. Epub 2020 May 10.

Pediatric Neuroradiology and Image Guided Therapy, Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, Toronto M5G 1H4, ON, Canada.

Purpose: The purpose of this study was to determine the additional information provided by Magnetic Resonance Angiography (MRA) in pediatric sickle cell disease (SCD) patients with normal Transcranial Doppler imaging (TCDI) examinations.

Methods: This cohort study included all pediatric SCD patients over an 18-year period who had no history of stroke and had normal TCDI examinations and subsequently underwent MRA. Routine TCDI inclusive of time-averaged mean of maximum velocities (TAMMV) were assesses and compared with tortuosity on MRA and silent infarct on MRI.

Results: 86 children (52.3% female; mean age 8.7 ± 3.5years) were included. There were 77 patients (89.5%) with Hb-SS disease and 9(10.4%) with HB-S beta-thalassemia. All patients had normal TAMMV (<170 cm/s) on TCDI. 76/86 (88.3%) patients also had one or more velocity readings <70 cm/s, albeit none in the middle cerebral arteries. Posterior cerebral arteries had the lowest velocities, <70 cm/s in 51.7% (right) and 60.9% (left). Silent MRI infarcts were seen in 27/86 (31.4%) patients. No new lesions were identified on follow-up MRI. Although mild vascular tortuosity was appreciated in 31/86 (36.0%) of the patients, there were no steno-occlusive lesions in the circle of Willis.

Conclusions: TCDI and MRA are routinely performed for non-invasively evaluating intracranial vascular abnormalities in children with SCD. In SCD children with no history of TIA or stroke, MRA following a normal TCDI examination is unlikely to show vascular abnormality. However, almost a third of these patients show silent infarcts on MRI, unassociated with MRA changes.
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http://dx.doi.org/10.1016/j.jstrokecerebrovasdis.2020.104864DOI Listing
July 2020

Use of Tissue Plasminogen Activator in Abdominal Abscesses in Children-A Single-Center Randomized Control Trial.

Can Assoc Radiol J 2020 Apr 13:846537120914263. Epub 2020 Apr 13.

Image Guided Therapy, Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada.

Purpose: To establish the efficacy of once-per-day intracavitary tissue plasminogen activator (tPA) in the treatment of pediatric intra-abdominal abscesses.

Methods: A single-center prospective, double-blinded, randomized controlled trial of the use of intracavitary tPA in abdominal abscesses in children. Patients were randomized to either tPA-treatment or saline-treatment groups. Primary outcome was drainage catheter dwell (hours). Secondary outcomes were length of hospital stay, times to discharge, clinical and sonographic resolution, and adverse events (AEs).

Results: Twenty-eight children were randomized to either group (n = 14 each). Demographics between groups were not significantly different (age = .28; weight = .40; gender = .44). There were significantly more abscesses in the tPA-treated group ( = .03). Abscesses were secondary to perforated appendicitis (n = 25) or postappendectomy (n = 3). Thirty-four abscesses were drained, 4 aspirated, 3 neither drained/aspirated. There was no significant difference in number of drains ( = .14), drain size ( = .19), primary outcome ( = .077), or secondary outcomes found. No procedural or intervention drug-related AEs occurred. No patient in the saline-treated group required to be switched/treated with tPA.

Conclusion: No significant difference in the length of catheter dwell time, procedure time to discharge, or time to resolution was found. Intracavitary tPA was not associated with morbidity or mortality. The results neither support nor negate routine use of tPA in the drainage of intra-abdominal abscess in children. It is possible that a multicentre study with a larger number of patients may answer this question more definitively.
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http://dx.doi.org/10.1177/0846537120914263DOI Listing
April 2020

After-hours radiology coverage in children's hospitals: a multi-center survey.

Pediatr Radiol 2020 06 12;50(7):907-912. Epub 2020 Mar 12.

Department of Diagnostic and Interventional Imaging, McGovern Medical School, UTHealth at Houston, Houston, TX, USA.

Background: Although the provision of pediatric emergency and trauma radiology has become increasingly prevalent in North America over the last few years, many hospitals differ in their models of providing after-hours coverage.

Objective: To describe the scope of after-hours radiology services provided in children's hospitals in North America, and the means by which different radiology departments deliver this coverage.

Materials And Methods: The Society for Pediatric Radiology Emergency and Trauma Imaging Committee developed a survey that we electronically distributed to a single representative from each of the 79 hospitals represented in the Society of Chiefs of Radiology at Children's Hospitals (SCORCH).

Results: Completed questionnaires were submitted between Aug. 2, 2017, and Sept. 29, 2017, by 44/79 (56%) SCORCH representatives. Contemporaneous after-hours interpretation of radiographs (81%), ultrasounds (81%), body CT (79%) and neurologic CT (75%) with preliminary or final reports was common. Coverage was accomplished most commonly by a combination of evening and overnight shifts 17/44 (39%). Eleven of 44 (25%) hospitals used a model in which radiologists rotate working blocks of overnight service followed by blocks off service. Only 2/44 (5%) hospitals exclusively provided pager coverage after hours. Attending pediatric radiologists were assigned to the majority of after-hours shifts 110/175 (63%), but radiology trainees provided interpretations independently for varying periods of time at 19/44 (43%) surveyed hospitals. Incentives to work after hours included the option to work remotely, as well as additional income, time off, and academic time.

Conclusion: The model for delivering after-hours pediatric radiology coverage varies. Most hospitals, however, provide contemporaneous interpretations of radiographs, US, body CT and neurologic CT. Most institutions use evening shifts to extend coverage later, with many providing subsequent overnight coverage. Although most shifts are staffed by attending pediatric radiologists, radiology trainees commonly interpret studies independently for varying durations of time after hours.
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http://dx.doi.org/10.1007/s00247-020-04647-8DOI Listing
June 2020

Magnetic Resonance Cholangiopancreatography Severity Predicts Disease Outcomes in Pediatric Primary Sclerosing Cholangitis: A Reliability and Validity Study.

Hepatol Commun 2020 Feb 6;4(2):208-218. Epub 2019 Dec 6.

Department of Diagnostic Imaging The Hospital for Sick Children Toronto Canada.

Magnetic resonance cholangiopancreatography (MRCP) has not been assessed as a surrogate biomarker in pediatrics. We aimed to determine the inter-rater reliability, prognostic utility, and construct validity of the modified Majoie endoscopic retrograde cholangiopancreatography classification applied to MRCP in a pediatric primary sclerosing cholangitis (PSC) cohort. This single-center, retrospective, cohort study included children with PSC undergoing diagnostic MRCP between 2008 and 2016. Six variations of the Majoie classification were examined: 1) intrahepatic duct (IHD) score, 2) extrahepatic duct (EHD) score (representing the worst intrahepatic and extrahepatic regions, respectively), 3) sum IHD-EHD score, 4) average IHD score, 5) average EHD score, and 6) sum average IHD-EHD score. Inter-rater reliability was assessed using weighted kappas and intraclass correlation coefficients (ICCs). Ability to predict time to PSC-related complications (ascites, esophageal varices, variceal bleed, liver transplant [LT], or cholangiocarcinoma) (primary outcome) and LT (secondary outcome) was assessed with Harrell's concordance statistic (c-statistic) and univariate/multivariable survival analysis. Construct validity was further assessed with Spearman correlations. Forty-five children were included (67% boys; median, 13.6 years). The inter-rater reliability of MRCP scores was substantial to excellent (kappas/ICCs, 0.78-0.82). The sum IHD-EHD score had the best predictive ability for time to PSC complication and LT (c-statistic, 0.80 and SE, 0.06; and c-statistic, 0.97 and SE, 0.01, respectively). Higher MRCP scores were independently associated with a higher rate of PSC-related complications, even after adjusting for the PSC Mayo risk score (hazard ratio, 1.74; 95% confidence interval, 1.14-2.). MRCP sum scores correlated significantly with METAVIR fibrosis stage, total bilirubin, and platelets ( = 0.42,  = 0.33,  = -0.31, respectively;  < 0.05). An MRCP score incorporating the worst affected intrahepatic and extrahepatic regions is reliable and predicts meaningful outcomes in pediatric PSC. Next steps include prospective validation and responsiveness assessment.
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http://dx.doi.org/10.1002/hep4.1454DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6996389PMC
February 2020

Volumetric assessment of unaffected parenchyma and Wilms' tumours: analysis of response to chemotherapy and surgery using a semi-automated segmentation algorithm in children with renal neoplasms.

BJU Int 2020 05 27;125(5):695-701. Epub 2020 Feb 27.

Division of Urology, Hospital for Sick Children and Department of Surgery, University of Toronto, Toronto, ON, Canada.

Objective: To present our proof of concept with semi-automatic image recognition/segmentation technology for calculation of tumour/parenchyma volume.

Methods: We reviewed Wilms' tumours (WTs) between 2000 and 2018, capturing computed tomography images at baseline, after neoadjuvant chemotherapy (NaC) and postoperatively. Images were uploaded into MATLAB-3-D volumetric image processing software. The program was trained by two clinicians who supervised the demarcation of tumour and parenchyma, followed by automatic recognition and delineation of tumour margins on serial imaging, and differentiation from uninvolved renal parenchyma. Volume was automatically calculated for both.

Results: During the study period, 98 patients were identified. Of these, based on image quality and availability, 32 (38 affected moieties) were selected. Most patients (65%) were girls, diagnosed at age 50 ± 37 months of age. NaC was employed in 64% of patients. Surgical management included 27 radical and 11 partial nephrectomies. Automated volume assessment demonstrated objective response to NaC for unilateral and bilateral tumours (68 ± 20% and 53 ± 39%, respectively), as well as preservation on uninvolved parenchyma with partial nephrectomy (70 ± 46 cm at presentation to 57 ± 41 cm post-surgery).

Conclusion: Volumetric analysis is feasible and allows objective assessment of tumour and parenchyma volume in response to chemotherapy and surgery. Our data show changes after therapy that may be otherwise difficult to quantify. Use of such technology may improve surgical planning and quantification of response to treatment, as well as serving as a tool to predict renal reserve and long-term changes in renal function.
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http://dx.doi.org/10.1111/bju.15026DOI Listing
May 2020

Preoperative delineation of pulmonary fissural anatomy at multi-detector computed tomography in children with congenital pulmonary malformations and impact on surgical complications and postoperative course.

Pediatr Radiol 2020 05 28;50(5):636-645. Epub 2020 Jan 28.

Department of Diagnostic Imaging, Hospital for Sick Children, 555 University Ave., Toronto, ON, M5G 1X8, Canada.

Background: Delineation of the anatomy and integrity of the pulmonary fissures at CT is important because anomalous or incomplete fissures might increase the risk of surgery and of postoperative complications.

Objective: To preoperatively evaluate the integrity of the pleural fissures in children with congenital lung malformations and determine whether anomalous fissural anatomy is a risk factor for a more complicated surgery and postoperative course.

Materials And Methods: We reviewed preoperative multi-detector CT scans of consecutive children who underwent open or thoracoscopic resection of a congenital pulmonary malformation from 2008 to 2018, to determine the integrity of the fissural anatomy, and compared these findings with the surgical report. We correlated postoperative factors including operating room time, days in hospital and chest tube with the operating room documented fissural integrity.

Results: We saw a significant association between the radiologically determined fissural integrity at CT and the operative findings independently for the right, left and both lungs combined (P<0.001). The sensitivity of CT to determine fissural integrity was 76.9%, specificity 95.2%, positive predictive value 95.2%, negative predictive value 76.9%, and accuracy 85.1%. There was a statistically significant association between size of the pulmonary malformation and the integrity of the fissure(s) (P=0.024). Larger lesions also resulted in a significantly longer hospitalization (P=0.024).

Conclusion: Chest CT showed high accuracy for delineating fissural anatomy in children with congenital pulmonary malformations, with a good interobserver correlation. Incomplete lung fissures were found more often in children with larger congenital pulmonary malformations. In addition, larger lesions were associated with longer hospital stays. Therefore, children with incomplete fissures may have a longer postoperative course. Analysis of the fissural anatomy should be included in the CT report.
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http://dx.doi.org/10.1007/s00247-020-04618-zDOI Listing
May 2020

Locations, associations and temporal evolution of intracranial arterial infundibular dilatations in children.

J Neurointerv Surg 2020 May 7;12(5):495-498. Epub 2019 Nov 7.

Department of Diagnostic Imaging & Image Guided Therapy, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.

Background: There are few data in the literature on the characteristics and natural history of intracranial arterial infundibular dilatations in children.

Methods: An institutional review board-approved retrospective review was performed of infundibula reported on MR angiography in patients <18 years of age at our tertiary pediatric institute from 1998 to 2016. Clinical data (age, sex, diagnosis, other vascular variants/pathologies) were recorded and images assessed for vessel of origin, infundibulum size and exact location. Ratios of infundibulum:parent artery were assessed at diagnosis and last follow-up. Temporal evolution to aneurysm was evaluated.

Results: We found 60 intracranial infundibula in 60 children (male:female=27:33; mean age 9.7±5.2 years, range 2-18 years,). Family history of aneurysms was present in 2/60 (3.3%). Syndromic association was found in 14/60 (23.3%), most frequently sickle cell disease (4/14=28.6%). Mean infundibulum size was 2.2±0.5 mm, with mean ratio to parent artery of 0.54±0.17. The most common location was on the P1-posterior cerebral artery (34/63=56.7%), whereas posterior communicating infundibula were seen in only 4/60 (6.7%) cases. Other cerebrovascular variants were seen in 12/60 (20%) patients. On follow-up imaging (in 32/60 patients over 86 patient-years, mean 32.3±35.7 months), no significant change in infundibulum:parent artery ratio was noted. None of the infundibular dilatations showed interval evolution to aneurysm.

Conclusion: We present the largest reported cohort of pediatric intracranial arterial infundibula, which we found to be distinct from their adult counterparts with regard to location, etiology and temporal evolution. Growth over time and/or aneurysmal formation are rare, not necessitating frequent short-term imaging surveillance during childhood.
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http://dx.doi.org/10.1136/neurintsurg-2019-015433DOI Listing
May 2020

The impact of F-FDG PET on initial staging and therapy planning of pediatric soft-tissue sarcoma patients.

Pediatr Radiol 2020 02 18;50(2):252-260. Epub 2019 Oct 18.

Diagnostic Imaging Department, The Hospital for Sick Children, University of Toronto, 555 University Ave., Toronto, ON, M5G 1X8, Canada.

Background: Soft-tissue sarcomas in children are a histologically heterogenous group of malignant tumors accounting for approximately 7% of childhood cancers. There is a paucity of data on the value of F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) for initial staging and whether PET influenced management of these patients.

Objective: The aim of this analysis is to assess the use of F-FDG PET exclusively, and as a supplement to cross-sectional imaging in comparison to typical imaging protocols (CT and magnetic resonance imaging [MRI]) for initial staging as well as therapy planning in pediatric soft-tissue sarcoma patients.

Materials And Methods: The list of F-FDG PET/CT performed for soft-tissue sarcoma between March 2007 and October 2017 was obtained from the Hospital Information System database. Twenty-six patients who had received F-FDG PET, MRI and/or CT at initial diagnosis were included in the study. F-FDG PET and concurrent diagnostic CT and MRI at initial staging were independently reviewed to note the number of primary and metastatic lesions detected by each modality. A chart review was conducted to collect information on final diagnosis, staging and treatment plan.

Results: During the study period, 26 patients (15 females) ages 1.3-17.9 years (median age: 6 years) had received F-FDG PET/CT at initial diagnosis of soft-tissue sarcoma. Diagnostic CT was available for comparison in all 26 patients and MRI was available in 18 patients. The mean interval between cross-sectional imaging and F-FDG PET was 5.9 days (range: 0-30 days). All 26 primary lesions were equally detected by F-FDG PET compared to CT and MRI. From 84 metastatic lesions, 16 were detected by PET as well as CT and MRI, 12 by F-FDG PET only (included mainly lymph node metastases) and 56 by CT and MRI only (included mainly lung metastases). F-FDG PET changed therapy planning in 5 patients out of 26 (19%) by showing additional lesions not detected by CT and MRI.

Conclusion: F-FDG PET proved to be a valuable tool for precise initial staging of pediatric soft-tissue sarcoma patients, especially in detecting lymph node metastasis, and could be included in their initial work-up. Given the relative rarity and heterogeneity of this group of tumors, additional investigations are required to definitely establish a role for F-FDG PET in the initial staging and therapy planning of soft-tissue sarcoma in the pediatric population.
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http://dx.doi.org/10.1007/s00247-019-04530-1DOI Listing
February 2020

Sample-Size Determination Methodologies for Machine Learning in Medical Imaging Research: A Systematic Review.

Can Assoc Radiol J 2019 Nov 12;70(4):344-353. Epub 2019 Sep 12.

Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada; Department of Statistical Sciences, University of Toronto, Toronto, Ontario, Canada. Electronic address:

Purpose: The required training sample size for a particular machine learning (ML) model applied to medical imaging data is often unknown. The purpose of this study was to provide a descriptive review of current sample-size determination methodologies in ML applied to medical imaging and to propose recommendations for future work in the field.

Methods: We conducted a systematic literature search of articles using Medline and Embase with keywords including "machine learning," "image," and "sample size." The search included articles published between 1946 and 2018. Data regarding the ML task, sample size, and train-test pipeline were collected.

Results: A total of 167 articles were identified, of which 22 were included for qualitative analysis. There were only 4 studies that discussed sample-size determination methodologies, and 18 that tested the effect of sample size on model performance as part of an exploratory analysis. The observed methods could be categorized as pre hoc model-based approaches, which relied on features of the algorithm, or post hoc curve-fitting approaches requiring empirical testing to model and extrapolate algorithm performance as a function of sample size. Between studies, we observed great variability in performance testing procedures used for curve-fitting, model assessment methods, and reporting of confidence in sample sizes.

Conclusions: Our study highlights the scarcity of research in training set size determination methodologies applied to ML in medical imaging, emphasizes the need to standardize current reporting practices, and guides future work in development and streamlining of pre hoc and post hoc sample size approaches.
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http://dx.doi.org/10.1016/j.carj.2019.06.002DOI Listing
November 2019

Procedural pain reduction strategies in paediatric nuclear medicine.

Pediatr Radiol 2019 09 17;49(10):1362-1367. Epub 2019 Jul 17.

Nuclear Medicine Division, The Hospital for Sick Children, University of Toronto, 2nd Floor Burton Wing, Room 2101, 555 University Ave., Toronto, ON, M5G 1X8, Canada.

Background: In paediatric nuclear medicine, the majority of the scans require intravenous (IV) access to deliver the radiotracers. Children and parents often cite procedural pain as the most distressing part of their child's hospitalization. In our department, various pain management strategies including physical and psychological distraction methods and pharmacological intervention have been implemented to reduce procedural pain.

Objective: The purpose of this study was to evaluate and compare different pain reduction strategies used in our paediatric nuclear medicine department.

Materials And Methods: The charts of 196 children (114 female) were reviewed retrospectively (median age: 8 months; interquartile range [IQR]: 33.1). Children were categorized into five groups: (1) Maxilene (topical liposomal lidocaine; n=50), (2) Pain Ease (vapocoolant; n=69), (3) oral sucrose (n=48), (4) Maxilene and Pain Ease combined (n=10), and (5) no pharmacological/adjuvant intervention (n=19). Physical and psychological distraction were used in all patients. Therefore, Group 5 only received physical and psychological strategies. Physical methods included supportive positioning, deep breathing, temperature considerations, massage pressure or vibration and neonatal development strategies (e.g., non-nutritive sucking, facilitated tucking, swaddling, rocking). Psychological strategies included education, distraction with movies, books or storytelling, and relaxation techniques. The pain perceived by the children after the IV access was compared in these five groups. Two types of pain assessment were used in this study: self-reporting pain scale and behavioural observational pain rating scale. Pain was reported on a scale of 1 to 10. The average pain score was also compared between patients who had one or two attempts for IV access and those who had more than two attempts.

Results: The average pain score was 2.8 (mean±standard error [SE]=0.4) in Maxilene, 2.1 (SE=0.3) in Pain Ease, 2.7 (SE=0.3) in sucrose, 1.6 (SE=0.5) in combined Maxilene and Pain Ease and 3.4 (SE=0.6) in "no pharmacology/adjuvant" groups. There was no statistically significant difference between the four pharmacology groups of Maxilene, Pain Ease, sucrose and no pharmacology/adjuvant intervention group. However, the pain score was significantly reduced in patients who received both Maxilene and Pain Ease combined compared with the patients who didn't have any pharmacological/adjuvant intervention (P=0.041). The average pain was 2.2 (SE=0.1) with one attempt at IV access, 3.0 (SE=0.5) with two attempts and 5.1 (SE=0.9) with three attempts.

Conclusion: A combination of two pharmacological/adjuvant interventions may be more effective in reducing procedural pain compared with a single intervention. A comprehensive pain management program should consider all available interventions - pharmacological, adjuvant, physical and psychological. Further randomized clinical trials are needed to evaluate if a combination of two or more methods of pharmacological and adjuvant interventions are more effective to reduce procedural pain compared with only one method.
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http://dx.doi.org/10.1007/s00247-019-04462-wDOI Listing
September 2019

Usefulness of diffusion-weighted MRI in the initial assessment of osseous sarcomas in children and adolescents.

Pediatr Radiol 2019 08 15;49(9):1201-1208. Epub 2019 Jun 15.

Department of Diagnostic Imaging, The Hospital for Sick Children, 555 University Ave., Toronto, ON, M5G 1X8, Canada.

Background: Concern regarding gadolinium deposition in the brain after repeated administration of intravenous gadolinium-based contrast agents has prompted evaluation of imaging alternatives.

Objective: The study purpose was to determine if magnetic resonance imaging (MRI) using conventional sequences with diffusion-weighted imaging (DWI) instead of gadolinium-based contrast-enhanced MRI is valid for local staging and guiding biopsies in osseous sarcomas.

Materials And Methods: Initial pretreatment MRI with DWI and gadolinium-based contrast-enhanced images in patients ≤ 18 years with histopathologically proven osseous sarcomas were included. Two radiologists blinded to collated demographic and clinical data, independently reviewed conventional/DWI and conventional/gadolinium-based contrast-enhanced MRI then conventional sequences alone, recording tumor size, skip lesions, necrosis, neurovascular invasion, enlarged lymph nodes and diffusion restriction. Discrepancies were resolved by a third reader. A single reader measured apparent diffusion coefficient (ADC) values in non-necrotic tumors, then correlated minimum ADC values -- with and without normalization to skeletal muscle -- with relative enhancement.

Results: Twenty-one patients (mean age: 11.3±4.2 years, 15 [71%] females) had 14 osteosarcomas and 7 Ewing sarcomas, 50% centered in the femur. Conventional/DWI versus conventional/gadolinium-based contrast-enhanced MRI showed agreement for tumor size estimation with significant associations for necrosis (P=0.021), neurovascular involvement (P<0.001) and enlarged lymph nodes (P=0.005). Diagnostic accuracy of conventional/DWI is comparable to conventional/gadolinium-based contrast-enhanced MRI and superior to conventional sequences alone. Comparison between minimum ADC values and relative enhancement showed no correlation (P>0.05).

Conclusion: Significant associations of key imaging features in the initial assessment of osseous sarcomas support DWI as an alternative to gadolinium-based contrast-enhanced MRI. The lack of association between ADC values and relative enhancement suggests that they measure independent constructs, DWI dependent upon tumor cellularity and perfusion.
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http://dx.doi.org/10.1007/s00247-019-04436-yDOI Listing
August 2019

Experience with Compressed Gelfoam Plugs in Children during Liver Biopsies and Other IR Procedures: A Retrospective Single-Center Case Series.

J Vasc Interv Radiol 2019 Nov 13;30(11):1855-1862. Epub 2019 Jun 13.

Department of Diagnostic Imaging, Division of Image Guided Therapy, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON, M5G 1X8, Canada.

Purpose: To analyze the experience using compressed gelfoam plugs (CGPs) in children during liver biopsies and other interventional procedures.

Materials And Methods: This was a single-center, retrospective, consecutive case series of 477 various pediatric interventional radiology procedures using CGPs (January 2012 to December 2016) performed on 397 children (209 males, 188 females; median age, 7 years [range, 9 days-17.8 years]; median weight, 18 kg [range, 2.7-141 kg]). Of 477 procedures, most (n = 371) were liver biopsies, 98 were biopsies of other organs, and 8 were non-biopsy procedures. Analysis focused on liver biopsies.

Results: Of liver biopsies, a median of 2 CGPs were used per procedure, and the mean drop in hemoglobin was -0.36 g/dl (-3.0% change). Thirty-seven mild, 8 moderate, 2 severe, and 1 life-threatening (an anaphylaxis to CGP) adverse events (AEs) occurred. Analysis of liver biopsies with AEs showed significant association between number of passes, cores, and focal-type lesions (unadjusted logistic regression: P = .007, P = .022, P = .028, respectively) and age, weight, and number of passes (adjusted multiple logistic regression: P = .006, P = .032, P = .046, respectively). Technical problems relating to CGP deployment were noted in 5 (1%), without any AEs.

Conclusions: CGPs were used in a wide variety of procedures and organs in children. There was 1 life-threatening AE resulting from the rare risk of anaphylaxis caused by the gelfoam-containing plug. After liver biopsies, transfusion was required in 2/371 (0.5%) procedures, 1 related to pre-biopsy anemia (0.25%).
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http://dx.doi.org/10.1016/j.jvir.2019.04.004DOI Listing
November 2019

Unruptured intracranial aneurysms in children: 18 years' experience in a tertiary care pediatric institution.

J Neurosurg Pediatr 2019 May 24;24(2):184-189. Epub 2019 May 24.

1Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, Ontario.

Objective: There are little data in the literature on the characteristics and natural history of unruptured intracranial aneurysms in children. The authors analyzed their experience with unruptured intracranial aneurysms in the pediatric population at their tertiary care pediatric institution over the last 18 years. The first objective was to assess the imaging characteristics and natural history of these aneurysms in order to help guide management strategies in the future. A second objective was to evaluate the frequency of an underlying condition when an incidental intracranial aneurysm was detected in a child.

Methods: The authors conducted a Research Ethics Board-approved retrospective review of incidental intracranial aneurysms in patients younger than 18 years of age who had been treated at their institution in the period from 1998 to 2016. Clinical (age, sex, syndrome) and radiological (aneurysm location, type, size, thrombus, mass effect) data were recorded. Follow-up imaging was assessed for temporal changes.

Results: Sixty intracranial aneurysms occurred in 51 patients (36 males, 15 females) with a mean age of 10.5 ± 0.5 years (range 9 months-17 years). Forty-five patients (88.2%) had a single aneurysm, while 2 and 3 aneurysms were found in 3 patients each (5.8%). Syndromic association was found in 22 patients (43.1%), most frequently sickle cell disease (10/22 [45.5%]). Aneurysms were saccular in 43 cases (71.7%; mean size 5.0 ± 5.7 mm) and fusiform in the remaining 17 (28.3%; mean size 6.5 ± 2.7 mm). Thirty-one aneurysms (51.7%) arose from the internal carotid artery (right/left 1.4), most commonly in the cavernous segment (10/31 [32.3%]). Mean size change over the entire follow-up of 109 patient-years was a decrease of 0.6 ± 4.2 mm (range -30.0 to +4.0 mm, rate -0.12 ± 9.9 mm/yr). Interval growth (2.0 ± 1.0 mm) was seen in 8 aneurysms (13.3%; 4 saccular, 4 fusiform). An interval decrease in size (8.3 ± 10.7 mm) was seen in 6 aneurysms (10%). There was an inverse relationship between aneurysm size and growth rate (r = -0.82, p < 0.00001). One aneurysm was treated endovascularly with internal carotid artery sacrifice.

Conclusions: Unruptured pediatric intracranial aneurysms are most frequently single but can occur in multiples in a syndromic setting. None of the cases from the study period showed clinical or imaging signs of rupture. Growth over time, although unusual and slow, can occur in a proportion of these patients, who should be identified for short-term imaging surveillance.
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http://dx.doi.org/10.3171/2019.4.PEDS18703DOI Listing
May 2019

Clinical Impact of Chronic Venous Changes Induced by Central Lines in Children: A Cohort with Abnormal Venograms.

J Vasc Interv Radiol 2019 May 27;30(5):715-723. Epub 2019 Mar 27.

Image Guided Therapy, Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, 555 University Ave, Toronto, ON, M5G 1X8, Canada.

Purpose: To explore the hypothesis that central venous stenosis/obstructions (CVS/O) in children are influenced by prior central venous access devices (CVADs) and are associated with future risk for thromboses.

Material And Methods: A convenience sample of 100 patients with abnormal venography (stenosis, collaterals, occlusions) documented during peripherally inserted central catheter (PICC) placements were identified from consecutive PICC placements (January 2008 to November 2012). The patients (41 males, 59 females, median age 2.7 years, median weight 11 kg) were categorized based on venographic presence (Group A, n = 53) or absence (Group B, n = 47) of visible connection to the superior vena cava. Each patient's CVAD history, before and after venography, was analyzed (until October 2016).

Results: Before venogram, Group B patients were associated with a higher number of previous CVADs, larger diameter devices, greater incidence of malposition, and more use of polyurethane catheters than Group A patients (P < .001). An ipsilateral PICC was successfully placed in 98% of Group A, compared to 32% of Group B (P < .001). After venogram, significantly more Doppler ultrasounds (DUS) were performed and thromboses diagnosed in Group B (57% and 36%) compared to Group A (21% and 8%) (P < .003; P = .001), respectively.

Conclusions: Previous catheter characteristics influenced the severity of venographic changes of CVS/O (Group B). Group B was associated with more subsequent symptomatic thromboses. This information may assist parents and referring physicians to anticipate potential adverse sequelae from CVS/O on the child's venous health.
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http://dx.doi.org/10.1016/j.jvir.2018.08.034DOI Listing
May 2019

Increased risk of symptomatic upper-extremity venous thrombosis with multiple peripherally inserted central catheter insertions in pediatric patients.

Pediatr Radiol 2018 07 27;48(7):1013-1020. Epub 2018 Feb 27.

Image Guided Therapy, Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.

Background: Peripherally inserted central catheters (PICCs) are associated with superficial and deep venous thrombosis of the arm.

Objective: The purpose of this study was to analyze the sequelae of repeated upper limb PICC insertions in children, in terms of the frequency of upper limb thrombosis in this patient group.

Materials And Methods: The study population included all children who underwent their first successful arm PICC insertion between January 2010 and December 2015. We included subsequent ipsilateral arm PICCs in the analysis. Patients were followed until March 2016 or until any alternative central venous line insertion. For each PICC insertion, we collected demographic variables and line characteristics. We correlated all symptomatic deep and superficial thromboses of the arm with the PICC database.

Results: Applying inclusion and exclusion criteria, 2,180 PICCs remained for analysis. We identified first, second, third and fourth PICC insertions in the same arm in 1,955, 181, 38 and 6 patients, respectively. In total there were 57 upper body deep symptomatic thrombotic events. An increasing odds ratio was seen with higher numbers of PICC insertions, which was significant when comparing the first with the third and fourth PICC insertions in the same arm (odds ratio [OR] 6.00, 95% confidence interval [CI] 2.25-16.04, P=0.0004). Double-lumen PICCs were associated with a significantly higher risk of thrombosis than single lumen (OR 2.77, 95% CI 1.72-4.47, P=0.0003).

Conclusion: Repetitive PICC insertions in the same arm are associated with an increased risk of symptomatic thrombosis. Double-lumen PICCs are associated with a higher risk of thrombosis compared to single-lumen lines.
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http://dx.doi.org/10.1007/s00247-018-4096-xDOI Listing
July 2018

Accuracy of magnetic resonance imaging for measuring maturing cartilage: A phantom study.

Clinics (Sao Paulo) 2016 Jul;71(7):404-11

University of Toronto, The Hospital for Sick Children, Department of Diagnostic Imaging, Toronto/ON, Canada.

Objectives: To evaluate the accuracy of magnetic resonance imaging measurements of cartilage tissue-mimicking phantoms and to determine a combination of magnetic resonance imaging parameters to optimize accuracy while minimizing scan time.

Method: Edge dimensions from 4 rectangular agar phantoms ranging from 10.5 to 14.5 mm in length and 1.25 to 5.5 mm in width were independently measured by two readers using a steel ruler. Coronal T1 spin echo (T1 SE), fast spoiled gradient-recalled echo (FSPGR) and multiplanar gradient-recalled echo (GRE MPGR) sequences were used to obtain phantom images on a 1.5-T scanner.

Results: Inter- and intra-reader reliability were high for both direct measurements and for magnetic resonance imaging measurements of phantoms. Statistically significant differences were noted between the mean direct measurements and the mean magnetic resonance imaging measurements for phantom 1 when using a GRE MPGR sequence (512x512 pixels, 1.5-mm slice thickness, 5:49 min scan time), while borderline differences were noted for T1 SE sequences with the following parameters: 320x320 pixels, 1.5-mm slice thickness, 6:11 min scan time; 320x320 pixels, 4-mm slice thickness, 6:11 min scan time; and 512x512 pixels, 1.5-mm slice thickness, 9:48 min scan time. Borderline differences were also noted when using a FSPGR sequence with 512x512 pixels, a 1.5-mm slice thickness and a 3:36 min scan time.

Conclusions: FSPGR sequences, regardless of the magnetic resonance imaging parameter combination used, provided accurate measurements. The GRE MPGR sequence using 512x512 pixels, a 1.5-mm slice thickness and a 5:49 min scan time and, to a lesser degree, all tested T1 SE sequences produced suboptimal accuracy when measuring the widest phantom.
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http://dx.doi.org/10.6061/clinics/2016(07)09DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4946528PMC
July 2016

MRI thresholds for discrimination between normal and mild temporomandibular joint involvement in juvenile idiopathic arthritis.

Pediatr Rheumatol Online J 2015 Dec 1;13:53. Epub 2015 Dec 1.

Department of Diagnostic Imaging, The Hospital for Sick Children, 555 University Avenue, Toronto, ON, M5G1X8, Canada.

Background: Currently there is no consensus agreement on the degree of enhancement in normal temporomandibular joints (TMJ) in children, which makes it difficult for clinicians to distinguish between the presence/absence of mild synovitis. Quantitative measurements of synovial and condylar enhancement may be useful additions to current qualitative methods on early MRI diagnosis and follow up of TMJ involvement in JIA. The purpose of the study is to establish thresholds/tendencies for quantitative measures that enable distinction between mild TMJ involvement and normal TMJ appearance based on the degree of synovial and bone marrow enhancement in JIA patients.

Methods: TMJ MRI examinations in 67 children with JIA and in 24 non-rheumatologic children who underwent MRI for neurologic/orbit indications were retrospectively assessed. As a priori determined TMJs of JIA patients were categorized into three groups by experienced staff radiologists based on the degree of synovial and condylar enhancement: no active disease (rheumatologic control), mild and moderate/severe findings. The signal intensity (SI) of the synovial tissue around each condyle and of the bone marrow was measured to calculate the enhancement ratio (ER) and relative SI change. The ER was calculated using signal to noise ratios, while relative SI change was calculated using signal intensities alone. Quantitative measurements of synovial and condylar enhancement of TMJs with mild or moderate/severe findings were compared with the rheumatologic and non-rheumatologic controls.

Results: Mean ER values were significantly different between the TMJs without active disease and those with mild and moderate/severe synovial enhancement, with highest values in the moderate/severe group (P < 0.0001). Similar findings were seen for condylar enhancement with P < 0.005. Relative SI change was unable to differentiate TMJs with mild synovitis from the two controls (P > 0.10). 27/60 (45%) TMJs without active disease had osteochondral changes. 8/40 (20%) TMJs in the mild group did not demonstrate any synovial thickening.

Conclusions: Quantitative signal to noise ratios of TMJ synovial and condylar enhancement generate thresholds/tendencies, which offer additional information to differentiate mild synovitis from normal TMJs in JIA patients. Osteochondral changes and synovial thickening may not be reliable indicators of active TMJ involvement and should be differentiated from synovial enhancement.
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http://dx.doi.org/10.1186/s12969-015-0051-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4665947PMC
December 2015

Metal Artifact Reduction: Added Value of Rapid-Kilovoltage-Switching Dual-Energy CT in Relation to Single-Energy CT in a Piglet Animal Model.

AJR Am J Roentgenol 2015 Sep;205(3):W352-9

1 Department of Radiology, The Hospital for Sick Children, Toronto, ON, Canada.

Objective: The purpose of this article is to evaluate virtual monochromatic spectral imaging and metal artifact reduction software for reducing metal artifact and to compare it with conventional single-energy CT (SECT) in an animal model.

Materials And Methods: Postmortem juvenile (n = 5) and adult (n = 1) swine specimens were scanned with SECT followed by a dual-energy CT (DECT) pediatric protocol after the insertion of two rods into their paraspinal thoracolumbar regions. Virtual monochromatic spectral images were extrapolated from DECT images at five monoenergetic levels (64, 69, 75, 88, and 105 keV) with and without the use of metal artifact reduction software. Images were evaluated by a 5-point scoring system for the extent of metallic artifacts and image interpretability in soft-tissue and bone windows. The density in the most pronounced artifact was measured. CT dose index was recorded.

Results: In studies without metal artifact reduction software, higher energy reconstructions resulted in fewer artifacts and better image interpretability in both soft-tissue and bone windows (p < 0.0001). Artifact density decreased from -792 HU at 64 keV to -128 HU at 105 keV without the use of metal artifact reduction software. No difference was noted in attributes' scores or in artifact density in studies using metal artifact reduction software (p > 0.05). DECT studies showed lower scores compared with SECT with regard to all attributes. A new faint perimetallic hypodense halo was seen in all studies with metal artifact reduction software. The CT dose index of DECT was 1.18-3.56 times higher than that of SECT techniques.

Conclusion: DECT at all energy levels with metal artifact reduction software and higher energy extrapolations without metal artifact reduction software reduced metallic artifact and enhanced image interpretability compared with SECT. Radiation dose with DECT could be significantly higher than SECT.
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http://dx.doi.org/10.2214/AJR.14.12547DOI Listing
September 2015

Evidence-based outcomes on diagnostic accuracy of quantitative ultrasound for assessment of pediatric osteoporosis - a systematic review.

Pediatr Radiol 2014 Dec 25;44(12):1573-87. Epub 2014 Jun 25.

Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, 555 University Ave., Toronto, M5G 1X8, Canada.

Background: Dual-energy absorptiometry (DXA) is the current reference standard for assessing pediatric osteoporosis; however due to its areal nature, it has limitations. Thus, quantitative ultrasound (QUS), a modality free of ionizing radiation, has been proposed as a potential surrogate for DXA.

Objective: To semi-quantitatively assess the diagnostic accuracy of QUS for evaluating pediatric osteoporosis according to the U.S. Preventive Services Task Force guidelines.

Materials And Methods: We retrieved articles on the diagnostic accuracy of quantitative US for assessing abnormal bone quality or quantity in patients of mean age ≤19 years from MEDLINE, EMBASE and Cochrane Library CCTR databases. Evidences were analyzed for reliability, construct and criterion validity, and responsiveness of quantitative US, according to the following questions: (1) How reliable is the acquisition of QUS measurements? (2) Is QUS diagnostically accurate to characterize bone strength and quality in osteoporotic children? (3) Is QUS sensitive to detect changes in bone status over time? (4) Is QUS able to predict future skeletal fractures/degeneration? Three reviewers independently evaluated the quality of reporting and methodological quality using the Standards for Reporting of Diagnostic Accuracy (STARD) and the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tools.

Results: Out of 262 retrieved references (215 unique), we included 28 studies (1,963 patients; 807 reported boys and 761 girls, others unspecified; reported mean age, 0-19 years). The mean quality of reporting score was "excellent" in 24/28 (86%) studies; 11/28 (39%) studies had "adequate" research design quality.

Conclusion: There is no evidence of the diagnostic value of QUS at the present time despite the overall excellent and adequate research design quality of primary studies. Although QUS can produce reliable measurements, insufficient evidence has been reported to support other clinimetric properties of this technique.
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http://dx.doi.org/10.1007/s00247-014-3041-xDOI Listing
December 2014

Systematic protocol for assessment of the validity of BOLD MRI in a rabbit model of inflammatory arthritis at 1.5 tesla.

Pediatr Radiol 2014 May 24;44(5):566-75. Epub 2013 Dec 24.

Department of Diagnostic Imaging, The Hospital for Sick Children, 555 University Ave., Toronto, Canada, M5G 1X8.

Background: Blood-oxygen-level-dependent (BOLD) MRI has the potential to identify regions of early hypoxic and vascular joint changes in inflammatory arthritis. There is no standard protocol for analysis of BOLD MRI measurements in musculoskeletal disorders.

Objective: To optimize the following BOLD MRI reading parameters: (1) statistical threshold values (low, r > 0.01 versus high, r > 0.2); (2) summary measures of BOLD contrast (percentage of activated voxels [PT%] versus percentage signal difference between on-and-off signal intensities [diff_on_off]); and (3) direction of BOLD response (positive, negative and positive + negative).

Materials And Methods: Using BOLD MRI protocols at 1.5 T, arthritic (n = 21) and contralateral (n = 21) knees of 21 juvenile rabbits were imaged at baseline and on days 1, 14 and 28 after a unilateral intra-articular injection of carrageenan. Nine non-injected rabbits served as external control knees (n = 18). By comparing arthritic to contralateral knees, receiver operating characteristic curves were used to determine diagnostic accuracy.

Results: Using diff_on_off and positive + negative responses, a threshold of r > 0.01 was more accurate than r > 0.2 (P = 0.03 at day 28). Comparison of summary measures yielded no statistically significant difference (P > 0.05). Although positive + negative (AUC = 0.86 at day 28) and negative responses (AUC = 0.90 at day 28) for PT% were the most diagnostically accurate, positive + negative responses for diff_on_off (AUC = 0.78 at day 28) also had acceptable accuracy.

Conclusions: The most clinically relevant reading parameters included a lower threshold of r > 0.01 and a positive + negative BOLD response. We propose that diff_on_off is a more clinically relevant summary measure of BOLD MRI, while PT% can be used as an ancillary measure.
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http://dx.doi.org/10.1007/s00247-013-2844-5DOI Listing
May 2014

Quantitative assessment of myocardial T2 relaxation times in cardiac amyloidosis.

J Magn Reson Imaging 2009 Nov;30(5):942-6

Division of Cardiothoracic Imaging, Department of Medical Imaging, University Health Network and Mount Sinai Hospital, Toronto, Canada.

Purpose: To evaluate cardiac MRI (CMR) in the diagnosis of cardiac amyloidosis by comparing the T2 relaxation times of left ventricular myocardium in a pilot patient group to a normal range established in healthy controls.

Materials And Methods: Forty-nine patients with suspected amyloidosis-related cardiomyopathy underwent comprehensive CMR examination, which included assessment of myocardial T2 relaxation times, ventricular function, resting myocardial perfusion, and late gadolinium enhancement (LGE) imaging. T2-weighted basal, mid, and apical left ventricular slices were acquired in each patient using a multislice T2 magnetization preparation spiral sequence. Slice averaged T2 relaxation times were subsequently calculated offline and compared to the previously established normal range.

Results: Twelve of the 49 patients were confirmed to have cardiac amyloidosis by biopsy. There was no difference in mean T2 relaxation times between the amyloid cases and normal controls (51.3 +/- 8.1 vs. 52.1 +/- 3.1 msec, P = 0.63). Eleven of the 12 amyloid patients had abnormal findings by CMR, eight having LGE involving either ventricles or atria and four demonstrating resting subendocardial perfusion defects.

Conclusion: CMR is a potentially valuable tool in the diagnosis of cardiac amyloidosis. However, calculation of myocardial T2 relaxation times does not appear useful in distinguishing areas of amyloid deposition from normal myocardium.
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http://dx.doi.org/10.1002/jmri.21918DOI Listing
November 2009