Publications by authors named "Mark A Nathan"

34 Publications

Repeat Sentinel Lymph Node Surgery in Recurrent Breast Cancer: Peritumoral vs. Periareolar Injections.

Clin Breast Cancer 2021 Feb 18. Epub 2021 Feb 18.

Department of Surgery, Mayo Clinic, Rochester, MN. Electronic address:

Background: In the setting of recurrent cancer, there is no standard methodology regarding the technical aspects of repeat sentinel lymph node (rSLN) surgery. We analyzed our institutional experience with attempted rSLN surgery to determine the optimal injection technique.

Materials And Methods: Single site, retrospective review of patients with prior lumpectomy for breast cancer who presented with recurrent or new ipsilateral breast cancer and underwent attempt at rSLN surgery from 2008 to 2017. Patients with prior mastectomy or no prior ipsilateral axillary operation were excluded.

Results: A total of 141 patients were included; 103 (73%) underwent successful rSLN biopsy procedure. Lymphoscintigraphy showed aberrant drainage in 32 (26%). Periareolar (PA) injection resulted in failed mapping in 23/99 (23%) and aberrant drainage in 25/85 (29%). By comparison, peritumoral (PT) injection had a 14/38 (37%) incidence of failed mapping and 7/37 (19%) aberrant drainage (P = .11 and .23, respectively). Of the patients with successful sentinel lymph node (SLN) biopsy procedure via PA injection, 11/76 (14%) were positive for metastatic disease as compared with 2/24 (8%) in PT injection. Sixteen patients had lymph node metastases; 13 (81%) were SLNs, including 3 positive aberrant SLNs. Five-year regional recurrence rates were 11.4% (95% confidence interval, 0%-21.5%) and 0% for PA and PT injection techniques, respectively.

Conclusion: PA and PT injections had a similar incidence of SLN identification and aberrant drainage. Preoperative lymphoscintigraphy is beneficial in patients with recurrent breast cancer given the higher incidence of aberrant drainage in this population. Patients who underwent PA injections had a higher incidence of regional recurrences but this difference was not statistically significant.
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http://dx.doi.org/10.1016/j.clbc.2021.02.004DOI Listing
February 2021

FDG PET/CT and MRI Features of Pathologically Proven Schwannomas.

Clin Nucl Med 2021 04;46(4):289-296

From the Departments of Radiology.

Purpose: The aim of this study was to examine the MRI and FDG PET/CT imaging features of pathologically proven schwannomas.

Patients And Methods: This institutional review board-approved retrospective study examined biopsy-proven schwannomas that underwent FDG PET/CT and/or MRI at our institution between January 1, 2002, and April 1, 2018. PET/CT features analyzed included SUVmax, metabolic ratios, volumetric metabolic measures, presence of calcification, and pattern of FDG activity. MRI features included T1/T2 signal, enhancement pattern, margins, perilesional edema, presence of muscular denervation, and size.

Results: Ninety-five biopsy-proven schwannomas were identified (40 with both PET and MRI, 35 with PET only, and 20 with MRI only), 46 females and 49 males, average age of 57.7 ± 15.3 years. The average largest dimension was 4.6 ± 2.7 cm, the average SUVmax was 5.4 ± 2.7, and lesion SUVmax/liver SUVmean was 2.2 ± 1.2. Eleven (15%) of 75 lesions had SUVmax greater than 8.1, 26/75 (35%) had SUVmax greater than 6.1, and 14/75 (19%) had lesion SUVmax/liver SUVmean greater than 3.0. On MRI, 29/53 (55%) demonstrated internal nonenhancing areas. Twenty-eight (70%) of 40 lesions with both MRI and PET demonstrated at least 1 imaging feature concerning for malignant peripheral nerve sheath tumor (irregular margins, internal nonenhancement, perilesional edema, heterogeneous FDG uptake, or SUVmax >8.1). Lesions with heterogeneous FDG activity had higher SUVmax (6.5 ± 0.5 vs 4.7 ± 0.4, P = 0.0031) and more frequent internal nonenhancement on MRI (P = 0.0218).

Conclusions: Schwannomas may be large, be intensely FDG avid, and demonstrate significant heterogeneity, features typically associated with malignant peripheral nerve sheath tumors. A significant proportion exhibit FDG activity above cutoff levels previously thought useful in differentiating malignant from benign peripheral nerve sheath tumors.
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http://dx.doi.org/10.1097/RLU.0000000000003485DOI Listing
April 2021

C-choline positron emission tomography/computed tomography for detection of disease relapse in patients with history of biochemically recurrent prostate cancer and prostate-specific antigen ≤0.1 ng/ml.

J Cancer Res Ther 2020 Sep 10. Epub 2020 Sep 10.

Department of Radiology, Mayo Clinic, Rochester, MN, USA.

Objectives: The objective was to evaluate the diagnostic performance of surveillance C-choline positron emission tomography/computed tomography (PET/CT) for the detection of disease relapse in patients with a history of biochemically recurrent (BCR) prostate cancer (PCa) and prostate-specific antigen (PSA) ≤0.1 ng/ml.

Materials And Methods: We included patients who had been treated for BCR PCa and had a surveillance C-choline PET/CT at serum PSA ≤0.1 ng/ml. Positive surveillance PET/CT was defined as a study that identified a new tracer-avid lesion or new tracer uptake in a previously treated lesion or both. Findings were confirmed against a composite radiologic-pathologic gold standard. Time to recurrence association analyses were performed for disease relapse risk with the use of Cox proportional hazards regression.

Results: In total, 13 (12.1%) of the 107 patients had positive surveillance PET/CT scans, confirmed on pathologic assessment (n = 5) and subsequent imaging (n = 8). Among these 13 patients, ten had distant metastases, two had local recurrence, and one had both. Nine of the ten patients with metastases had oligometastatic disease defined as the presence of ≤3 metastases. Serum PSA became detectable again in only seven patients with positive surveillance PET/CT, after a mean interval from surveillance PET/CT of 292 days (range: 105-543 days). We identified an association of N stage with increased risk of recurrence (hazard ratio = 3.85; P = 0.036) although this was not significant after accounting for multiple testing.

Conclusions: Surveillance C-choline PET/CT can detect early disease relapse at serum PSA ≤0.1 ng/ml in patients with a history of BCR PCa.
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http://dx.doi.org/10.4103/jcrt.JCRT_373_19DOI Listing
September 2020

Percutaneous Image-Guided Nodal Biopsy After 11C-Choline PET/CT for Biochemically Recurrent Prostate Cancer: Imaging Predictors of Disease and Clinical Implications.

Adv Radiat Oncol 2019 Jan-Mar;4(1):79-89. Epub 2018 Sep 5.

Department of Radiology, Mayo Clinic, Rochester, Minnesota.

Purpose: Management of recurrent prostate cancer necessitates timely diagnosis and accurate localization of the sites of recurrent disease. The purpose of this study was to assess predictors of histologic outcomes after 11C-choline positron emission tomography/computed tomography (CholPET) to increase the positive predictive value and specificity of CholPET in identifying imaging predictors of malignant and benign nodal disease to better inform clinical decision making regarding local therapy planning.

Materials And Methods: Retrospective review of patients undergoing CholPET followed by percutaneous core needle biopsy between January 1, 2010 and January 1, 2016. A total of 153 patients were identified who underwent 166 biopsy procedures. Patient, CholPET, procedural, and pathologic characteristics were recorded.

Results: A total of 157 biopsies were technically successful, and 110 (70.1%; 95% confidence interval, 62.2-77.1) yielded histologic results abnormal for metastatic prostate cancer. Lesion location, lesion maximum standardized uptake value (SUVmax), SUV ratio (calculated as the ratio of SUVmax to SUV mean in the right atrium), prostate-specific antigen, lesion short axis length, total Gleason score, and castration resistance were all associated with abnormal biopsy results ( values <.001, <.001, <.001, .02, .02, .02, and .015, respectively). External iliac, common iliac, and inguinal sites were associated with much lower rates of histologic positivity (mean [95% confidence interval], 51.2% [35.1-67.1], 46.2% [19.2-74.9], and 33.3% [7.5-70.1]), respectively.

Conclusions: In a cohort of patients in whom core needle biopsy was performed after CholPET, characteristics of choline localization including node location, SUVmax, lesion-to-blood pool SUV ratio, prostate-specific antigen, total Gleason score, and castration resistance were significantly associated with abnormal biopsy results for metastatic disease on CholPET. Relatively high false positive rates were found in common iliac, external iliac, and inguinal lymph node locations. Histologic confirmation of these sites should be strongly considered in the appropriate clinical scenario before designing additional local therapy plans.
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http://dx.doi.org/10.1016/j.adro.2018.08.022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6349661PMC
September 2018

Multimodal Imaging Aids in the Diagnosis of Perineural Spread of Prostate Cancer.

World Neurosurg 2019 Feb 9;122:e235-e240. Epub 2018 Oct 9.

Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, USA. Electronic address:

Background: The perineural spread of prostate cancer into pelvic peripheral nerves is a rare, but increasingly recognized, entity. This form of metastasis invades the lumbosacral plexus via the splanchnic nerves innervating the prostate. The prevalence of perineural spread is likely underappreciated, and further imaging-based studies are needed to elucidate its true frequency.

Methods: A retrospective review was performed using an institutional radiology database. Medical reports from patients with prostate cancer who had undergone positron emission tomography (PET) imaging were queried for terms suggestive of perineural spread. PET and magnetic resonance imaging (MRI) from the identified patients were blindly reviewed for peripheral nerve involvement by 2 nuclear medicine and 2 musculoskeletal radiologists.

Results: A total of 22 patients were identified. After review by the radiologists, 16 patients had positive findings of perineural spread found on PET and 15 had abnormalities found on MRI involving lumbosacral plexus neural elements. All patients with biopsy-proven neoplastic perineural spread (including 1 patient with malignant peripheral nerve sheath tumor) had positive findings on both PET and MRI. All patients with biopsy-proven inflammatory lesions had negative PET and variable MRI findings.

Conclusions: The perineural spread of prostate cancer might be more common than previously thought. The use of multimodal imaging for patients suspected of having perineural spread should be a part of the treatment algorithm. Targeted fascicular biopsy might be indicated for patients with progressive neurological deficit and an unclear diagnosis.
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http://dx.doi.org/10.1016/j.wneu.2018.09.221DOI Listing
February 2019

Pittsburgh compound B (PiB) PET imaging of meningioma and other intracranial tumors.

J Neurooncol 2018 Jan 8;136(2):373-378. Epub 2017 Nov 8.

Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN, 55905, USA.

Meningiomas are the most common intracranial tumors. Diagnosis by MRI is generally straightforward, but lack of imaging specificity can present a diagnostic dilemma, particularly in patients with cancer. We report our experience with meningioma identification on Pittsburgh compound B (PiB) PET/CT. Patients who underwent PiB PET/CT from 2006 to 2015 were reviewed to identify those with intracranial tumors. Tumor types were classified by MR appearance, or by pathology when available. Maximum standardized uptake value (SUVmax) measurements of tumor PiB activity were compared across tumor types. 2472 patients underwent PiB PET/CT in the period of interest; 45 patients (1.8%) had probable or definite intracranial tumor. Tumor types were meningioma (29/45, 64%), vestibular schwannoma (7/45, 16%), pituitary macroadenoma (4/45, 9%), metastatic disease (2/45, 4%), and others (3/45, 7%). In patients with meningioma, the mean lesion SUVmax was 2.05 (SD 1.37), versus 1.00 (SD 0.42) in patients with non-meningioma tumors (p < 0.01). A receiver operating curve was created for lesion:cerebellum SUVmax ratio, with an area under the curve of 0.91 for a value of 1.68. At or above this ratio, specificity for meningioma was 100% (95% CI 79-100%) and sensitivity was 76% (95% CI 57-90%). PiB PET activity within an intracranial tumor is a highly specific and reasonably sensitive marker of meningioma. Further prospective evaluation is warranted to validate this result as well as to assess the performance of commercially available beta-amyloid radiotracers in meningioma identification.
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http://dx.doi.org/10.1007/s11060-017-2661-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5770483PMC
January 2018

Diagnostic performance of unenhanced computed tomography and F-fluorodeoxyglucose positron emission tomography in indeterminate adrenal tumours.

Clin Endocrinol (Oxf) 2018 Jan 5;88(1):30-36. Epub 2017 Sep 5.

Department of Radiology, Mayo Clinic, Rochester, MN, USA.

Objective: Evidence on the diagnostic performance of adrenal imaging is limited. We aimed to assess the diagnostic performance of unenhanced computed tomography (CT) and F-fluorodeoxyglucose ( FDG) positron emission tomography (PET)/CT imaging in a high-risk population for adrenal malignancy using an optimal reference standard.

Design: Retrospective cohort study.

Methods: Imaging studies of patients with adrenal nodules who underwent adrenal biopsy and/or adrenalectomy between 1994 and 2014 were reviewed and compared to the reference standard of histology. Eighty % of patients presented with known or suspected extra-adrenal malignancy.

Results: Unenhanced abdominal CT was performed in 353 patients with adrenal lesions; median size was 3 (0.7-15) cm and median radiodensity was 33 (-21-78) Hounsfield units (HU). Radiodensity of >10 HU diagnosed malignancy with a sensitivity of 100%, specificity of 33%, positive predictive value (PPV) of 72% and negative predictive value (NPV) of 100%. FDG-PET/CT was performed in 89 patients; median tumour size was 2.1 (0.7-9.2) cm. Maximum standardized uptake (SUV max) was higher in malignant lesions when compared to benign lesions (median=10 [2.3-29.4] vs 3.7 [1.4-24.5], respectively, P<.0001). Similarly, median SUV max lesion to SUV max liver ratio (ALR) in malignant lesions was higher than in benign lesions (median=3 [0.74-13.4] vs 1.2 [0.5-6.6], respectively, P<.0001). FDG-PET/CT ALR >1.8 diagnosed malignancy with a sensitivity of 87%, specificity of 84%, PPV of 85% and NPV of 86%.

Conclusion: Noncontract CT radiodensity of ≤10 HU excludes malignancy even in a high-risk population. For indeterminate adrenal lesions, given a superior specificity, FDG-PET/CT could be considered as a second stage imaging study.
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http://dx.doi.org/10.1111/cen.13448DOI Listing
January 2018

"Pseudo-progression" in advanced thyroid cancer in response to kinase inhibitor therapy.

Endocrine 2017 07 16;57(1):187-188. Epub 2017 May 16.

Mayo Clinic Minnesota, Rochester, MN, USA.

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http://dx.doi.org/10.1007/s12020-017-1321-6DOI Listing
July 2017

Patterns of Recurrence After Postprostatectomy Fossa Radiation Therapy Identified by C-11 Choline Positron Emission Tomography/Computed Tomography.

Int J Radiat Oncol Biol Phys 2017 03 17;97(3):526-535. Epub 2016 Nov 17.

Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota. Electronic address:

Purpose: To evaluate C-11 choline positron emission tomography/computed tomography (CholPET) in staging and determining patterns of recurrence in prostate cancer patients with rising prostate-specific antigen levels after prostatectomy radiation therapy (RT).

Methods And Materials: The study includes patients with biochemical failure after postprostatectomy RT who underwent CholPET between 2008 and 2015. Patient and disease characteristics were examined in relation to sites of recurrence. All RT dosimetry records were reviewed, and recurrences were mapped on a representative computed tomography dataset with their relationship relative to the irradiated fossa field as out of field (OOF), edge of field (EOF; recurrence within <45-Gy isodose lines), or in field (IF; recurrence within ≥45-Gy isodose lines).

Results: Forty-one patients were identified with 121 sites of recurrence (median 2 sites; interquartile range [IQR], 1-4). The median prostate-specific antigen level at CholPET was 3.1 (IQR, 1.9-5.6) ng/mL. Median interval from RT to biochemical failure was 24 (IQR, 10-46) months, with recurrence identified on CholPET at a median of 15 (IQR, 7-28) months from biochemical failure. Histologic confirmation of recurrence was obtained in 20 patients (49%), with the remainder confirmed by treatment response. Five patients (12%) had IF recurrences, 10 patients (24%) had EOF recurrences (median dose 10 Gy; IQR, 5-30 Gy), and 36 patients (88%) had OOF recurrences. Ten patients had combination failures: 6 (15%) EOF/OOF and 4 (10%) IF/OOF. Fifty-seven recurrences (47%) were pelvic nodal sites inferior to the L5-S1 interspace, of which 52 (43%) were within a pelvic RT field. Eighty-one recurrences (67%) were nodal and inferior to the aortic bifurcation.

Conclusions: Using CholPET, we found that the majority of patients evaluated for biochemical failure recurred outside of the postprostatectomy RT field. Furthermore, most recurrence sites were nodal and inferior to the aortic bifurcation. These results provide data that may be useful for examining strategies that include elective lymph node irradiation in postprostatectomy patients.
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http://dx.doi.org/10.1016/j.ijrobp.2016.11.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5308881PMC
March 2017

Identification of Site-specific Recurrence Following Primary Radiation Therapy for Prostate Cancer Using C-11 Choline Positron Emission Tomography/Computed Tomography: A Nomogram for Predicting Extrapelvic Disease.

Eur Urol 2017 03 3;71(3):340-348. Epub 2016 Sep 3.

Department of Urology, Mayo Clinic, Rochester, MN, USA.

Background: Management of recurrent prostate cancer (CaP) after radiotherapy (RT) is dependent on accurate localization of the site of recurrent disease.

Objective: To describe the anatomic patterns and clinical features associated with CaP recurrence following RT identified on advanced imaging.

Design, Setting, And Participants: Retrospective review of 184 patients with a rising prostate-specific antigen (PSA) after RT for CaP.

Intervention: C-11 choline positron emission tomography/computed tomography (CholPET).

Outcome Measurements And Statistical Analysis: Recurrence patterns were classified as pelvic soft tissue only (as a surrogate for potentially salvageable disease) versus any extrapelvic disease, and clinical features were compared between patterns. Multivariable logistic regression was used to generate a predictive nomogram for extrapelvic recurrence. Discrimination was assessed with a c-index.

Results And Limitations: Recurrence site was identified in 161 (87%) patients, with 95 (59%) sites histologically confirmed. Factors associated with the detection of recurrence included the difference between PSA nadir and PSA at CholPET (odds ratio: 1.30, p<0.01) and National Comprehensive Cancer Network high-risk classification (odds ratio: 10.83, p=0.03). One hundred (54.3%) patients recurred in the pelvic soft tissue only, while 61 (33%) had extrapelvic recurrence. Of 21 patients who underwent CholPET prior to meeting the Phoenix criteria of biochemical failure, 15 (71%) had recurrence identified on CholPET with 11 localized to the pelvis. On multivariable analysis, the difference between PSA nadir and PSA at CholPET, time from RT, and National Comprehensive Cancer Network risk group were predictive of recurrence outside of the pelvis, and a nomogram was generated with a c-index of 0.79.

Conclusions: CholPET identified the site of recurrence in 87% of patients with a rising PSA after RT; most commonly within the pelvis in potentially salvageable locations. A predictive nomogram was generated, and pending external validation, this may aid in assessing the risk of disease beyond the pelvis. These findings underscore the importance of advanced imaging when considering management strategies for patients with a rising PSA following primary RT.

Patient Summary: We identified anatomic patterns of recurrence in patients with a rising prostate-specific antigen after radiotherapy using C-11 choline positron emission tomography/computed tomography. Most recurrences were localized to the pelvis and we were able to generate a tool to aid in disease localization prior to evaluation with advanced imaging.
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http://dx.doi.org/10.1016/j.eururo.2016.08.055DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5729924PMC
March 2017

Utility of F-FDG PET for Predicting Histopathologic Response in Esophageal Carcinoma following Chemoradiation.

J Thorac Oncol 2017 01 26;12(1):121-128. Epub 2016 Aug 26.

Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota. Electronic address:

Introduction: For patients with esophageal cancer undergoing neoadjuvant chemoradiation (CRT) followed by surgical resection, complete histopathologic response (pCR) is associated with favorable overall survival (OS). The aim of this study was to evaluate the correlation between F-fluorodeoxyglucose positron emission tomography (FDG PET) response to neoadjuvant CRT and pCR.

Methods: Maximum standardized uptake values and standardized uptake ratios (SURs) were measured before and after CRT. SUR was normalized to liver uptake and mediastinal blood pool uptake. FDG PET complete response was defined as metabolic activity normalization to hepatic and blood pool activity. The correlation between FDG PET parameters and pCR was examined through logistic regression analyses.

Results: In total, 193 patients were monitored for a median of 3.6 years after initiation of CRT. Most tumors were adenocarcinoma (85%) and stage T3 (75%). Complete FDG PET response and pCR occurred in 27% and 34% of patients, respectively. Histologic findings, chemotherapy type, tumor stage, and radiation dose were not significantly associated with complete radiographic response. The rates of pCR in patients with and without radiographic complete response were 42% and 31% (p = 0.17), respectively. No predictive correlation was found between pCR and change in maximum standardized uptake value (p = 0.25), in SUR normalized to blood pool uptake (p = 0.20), or in SUR normalized to liver uptake (p = 0.15). The 5-year OS rate was 46% for patients with a complete FDG PET response versus 44% without a complete response (p = 0.78). The 5-year OS rate of patients who achieved pCR was 49% versus 43% for patients with residual tumor (p = 0.04).

Conclusion: For patients with esophageal cancer who received neoadjuvant chemoradiation, pretreatment and posttreatment FDG PET parameters did not correlate with pCR or OS.
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http://dx.doi.org/10.1016/j.jtho.2016.08.136DOI Listing
January 2017

Procedural and clinical outcomes of percutaneous adrenal biopsy in a high-risk population for adrenal malignancy.

Clin Endocrinol (Oxf) 2016 Nov 20;85(5):710-716. Epub 2016 Jun 20.

Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic, Rochester, MN, USA.

Objective: The role of percutaneous adrenal biopsy in a high-risk population for adrenal malignancy has not been fully investigated. Our aim was to describe the clinical presentation leading to the adrenal biopsy and evaluate the diagnostic performance, complications and non diagnostic rate of adrenal biopsy.

Design: Single-centre, retrospective cohort study.

Patients And Measurements: Medical records of patients who underwent adrenal biopsy between 1994 and 2014 were reviewed. Adrenal biopsy outcome was compared to a predefined reference standard.

Results: Biopsy was performed in 418 patients [62% men, median age 69 years (range, 15-91)] on 419 adrenal lesions, median size 3·1 cm (range, 0·6-24). The main indication for adrenal mass biopsy was (349/419, 83%) suspected adrenal metastasis from a known or suspected extra-adrenal primary source. Only 116 of 419, 28% of cases had prebiopsy biochemical testing for pheochromocytoma. Biopsy-related complications occurred in 4% of the patients. Histology revealed a metastasis in 231 of 419 (55%), benign adrenal tissue in 137 of 419 (33%), adrenocortical carcinoma in eight of 419 (2%), other lesions in 23 of 419 (5%) including seven cases of pheochromocytoma and six cases of infectious process. Biopsy was nondiagnostic in 20 of 419 (5%). All adrenal masses with unenhanced radiodensity ≤10 HU (42/137, 31%) proved to be benign adrenal adenomas. Adrenal biopsy diagnosed malignancy with a sensitivity of 88·5%, specificity of 91·5%, positive predictive value of 93·4% and negative predictive value of 85·5%.

Conclusion: When used in the appropriate clinical setting, adrenal biopsy is a powerful tool in the diagnostic algorithm of the evaluation of adrenal masses with features suspicious for malignancy. Efforts to increase awareness to perform biochemical testing for pheochromocytoma prior to adrenal biopsy are needed.
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http://dx.doi.org/10.1111/cen.13117DOI Listing
November 2016

Evaluation of (18)F-FDG PET and MRI in differentiating benign and malignant peripheral nerve sheath tumors.

Skeletal Radiol 2016 Aug 26;45(8):1097-105. Epub 2016 Apr 26.

Department of Radiology, Mayo Clinic, Charlton Building North, 1st Floor, 200 First Street SW, Rochester, MN, 55905, USA.

Objective: To compare 18F-FDG PET/CT and MRI for differentiating benign and malignant peripheral nerve sheath tumors (BPNSTs and MPNSTs) and correlate imaging characteristics with histopathology.

Materials And Methods: Patients with pathologically proven PNSTs undergoing 18F-FDG PET/CT were retrospectively reviewed. PET/CTs and, if available, MRIs were analyzed, noting multiple imaging characteristics and likely pathology (benign or malignant).

Results: Thirty-eight patients with 23 BPNSTs and 20 MPNSTs were analyzed. MPNSTs had higher SUVmax (10.1 ± 1.0, 4.2 ± 0.4, p < 0.0001), metabolic tumor volume (146.5 ± 39.4, 21.7 ± 6.6 cm(3), p = 0.01), total lesion glycolysis (640.7 ± 177.5, 89.9 ± 23.2 cm(3)*g/ml, p = 0.01), and SUVmax/LiverSUVmean (5.3 ± 0.5, 2.0 ± 0.2, p < 0.0001). All lesions with SUVmax < 4.3 were benign. All lesions with SUVmax > 8.1 were malignant. SUVmax cutoff of 6.1 yielded 90.0 % sensitivity and 78.3 % specificity for MPNSTs. SUVmax/LiverSUVmean cutoff of 3.0 yielded 90.0 % sensitivity and 82.6 % specificity. MPNSTs more commonly had heterogeneous FDG activity (p < 0.0001), perilesional edema (p = 0.004), cystic degeneration/necrosis (p = 0.015), and irregular margins (p = 0.004). There was no difference in lesion size, MRI signal characteristics, or enhancement. Expertly interpreted MRI had 62.5-81.3 % sensitivity and 94.1-100.0 % specificity while PET had 90.0-100.0 % sensitivity and 52.2-82.6 % specificity for diagnosing MPNSTs.

Conclusions: FDG PET and MRI play a complementary role in PNST evaluation. Multiple metabolic parameters and MRI imaging characteristics are useful in differentiating BPNSTs from MPNSTs. This underscores the potential critical role of PET/MRI in these patients.
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http://dx.doi.org/10.1007/s00256-016-2394-7DOI Listing
August 2016

Comparison of facet joint activity on 99mTc-MDP SPECT/CT with facet joint signal change on MRI with fat suppression.

Diagn Interv Radiol 2016 May-Jun;22(3):277-83

Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.

Purpose: We compared signal change on magnetic resonance imaging (MRI) with fat suppression and bone scan activity of lumbar facet joints to determine if these two imaging findings are correlated.

Methods: We retrospectively identified all patients who underwent imaging of the lumbar spine for pain evaluation using both technetium-99m methylene disphosphonate single-photon emission computed tomography/computed tomography (99mTc-MDP SPECT/CT) and MRI with at least one fat-suppressed T2- or T1-weighted sequence with gadolinium enhancement within a 180-day interval, at our institution between 1 January 2008 and 19 February 2013. Facet joint activity on 99mTc-MDP SPECT/CT and peri-facet signal change on MRI were rated as normal or increased. Agreement between the two examination types were determined with the κ and prevalence-adjusted bias-adjusted κ (PABAK) statistics.

Results: This study included 60 patients (28 male, 47%), with a mean age of 49±19.7 years (range, 12-93 years). The κ value indicated no agreement between 99mTc-MDP SPECT/CT and MRI (κ=-0.026; 95% confidence interval: -0.051, 0.000). The PABAK values were fair to high at each spinal level, which suggests that relatively low disease prevalence lowered the κ values. Together, the κ and PABAK values indicate that there is some degree of intermodality agreement, but that it is not consistent.

Conclusion: Overall, facet joint signal change on fat-suppressed MRI did not always correlate with increased 99mTc-MDP SPECT/CT activity. MRI and 99mTc-MDP SPECT/CT for facet joint evaluation should not be considered interchangeable examinations in clinical practice or research.
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http://dx.doi.org/10.5152/dir.2015.15203DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4859746PMC
May 2017

BRAF Inhibitor-Induced Panniculitis: Appearance on 18F-FDG PET/CT.

Clin Nucl Med 2016 Mar;41(3):e149-51

From the Department of Radiology, Mayo Clinic, Rochester, MN.

BRAF inhibitors vemurafenib and dabrafenib have become the standard of care for treatment of stage IV metastatic melanoma harboring a BRAF mutation. Panniculitis is a rare but known adverse side effect of these agents and presents with tender erythematous nodules. These nodules may demonstrate uptake on F-FDG PET/CT, which may mimic metastatic disease in patients undergoing treatment. We present a case of BRAF inhibitor-induced panniculitis in a patient with stage IV metastatic melanoma and discuss the imaging findings on F-FDG PET/CT.
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http://dx.doi.org/10.1097/RLU.0000000000001027DOI Listing
March 2016

Detection of recurrent prostate cancer after radical prostatectomy: comparison of 11C-choline PET/CT with pelvic multiparametric MR imaging with endorectal coil.

J Nucl Med 2014 Feb 16;55(2):223-32. Epub 2014 Jan 16.

Department of Radiology, Mayo Clinic, Rochester, Minnesota; and.

Unlabelled: The aim of this study was to compare (11)C-choline PET/CT with pelvic multiparametric MR imaging for detection of recurrent prostate carcinoma in patients with suspected recurrence after radical prostatectomy and to identify an optimal imaging method to restage these patients.

Methods: This was a retrospective, single-institution study of 115 prostatectomy patients with suspected tumor recurrence who underwent both (11)C-choline PET/CT and multiparametric MR imaging with endorectal coil. The reference standard included histopathology, treatment change, and imaging follow-up for determination of locally recurrent tumor, lymph node (LN) metastases, and skeletal metastases. Two nuclear medicine and 2 genitourinary radiologists independently and in a masked manner reviewed PET/CT and multiparametric MR imaging, respectively. The reviewers assessed for local recurrence in the prostatectomy bed as well as LN and bone metastases, rating their diagnostic confidence with a 5-point scoring system for each location. Receiver-operating-characteristic analysis was used to compare the 2 modalities.

Results: The standard of reference (either positive or negative) for the diagnosis of local recurrence and pelvic LN and bone metastases was met in 87, 70, and 95 patients, respectively. Documented local recurrence and pelvic LN and bone metastases was present in 61 of 87 (70.1%), 50 of 70 (71.4%), and 16 of 95 (16.8%) patients, respectively. Patient-based area under the receiver-operating-characteristic curves of multiparametric MR imaging versus PET/CT for the diagnosis of local recurrence and pelvic LN and bone metastases were 0.909 versus 0.761 (P = 0.0079), 0.812 versus 0.952 (P = 0.0064), and 0.927 versus 0.898 (P = 0.69), respectively. Among 61 patients with local recurrence, 32 patients (52.4%) were correctly diagnosed as having local recurrence by both multiparametric MR imaging and PET/CT, 22 (36.1%) were correctly diagnosed by multiparametric MR imaging only, 6 (9.8%) could not be diagnosed by either modality, and 1 (1.6%) was correctly diagnosed by PET/CT only. The patient-based sensitivity, specificity, and accuracy of multiparametric MR imaging for diagnosing local recurrence were 88.5% (54/61), 84.6% (22/26), and 87.4% (76/87) whereas those of PET/CT for detecting body LN or bone metastases were 92.3% (72/78), 100% (18/18), and 93.8% (90/96), respectively.

Conclusion: Multiparametric MR imaging with endorectal coil is superior for the detection of local recurrence, PET/CT is superior for pelvic LN metastasis, and both were equally excellent for pelvic bone metastasis. (11)C-choline PET/CT and pelvic multiparametric MR imaging are complementary for restaging prostatectomy patients with suspected recurrent disease.
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http://dx.doi.org/10.2967/jnumed.113.123018DOI Listing
February 2014

Update on positron emission tomography for imaging of prostate cancer.

Int J Urol 2014 Jan 1;21(1):12-23. Epub 2013 Sep 1.

Department of Radiology, Kobe University School of Medicine, Kobe, Japan.

Prostate cancer is the most common non-cutaneous malignancy among men in the Western world, and continues to be a major health problem. Imaging has recently become more important in the clinical management of prostate cancer patients, including diagnosis, staging, choice of optimal treatment strategy, treatment follow up and restaging. Positron emission tomography, a functional and molecular imaging technique, has opened a new field in clinical oncological imaging. The most common positron emission tomography radiotracer, 18F-fluorodeoxyglucose, has been limited in imaging of prostate cancer. Recently, however, other positron emission tomography tracers, such as 11C-acetate and 11C- or (18) F-choline, have shown promising results. In the present review article, we overview the potential and current use of positron emission tomography or positron emission tomography/computed tomography imaging employing the four most commonly used positron emission tomography radiotracers, 18F-fluorodeoxyglucose, 11C-acetate and 11C- or 18F-choline, for imaging evaluation of prostate cancer.
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http://dx.doi.org/10.1111/iju.12250DOI Listing
January 2014

Individualized kV selection and tube current reduction in excretory phase computed tomography urography: potential for radiation dose reduction and the contribution of iterative reconstruction to image quality.

J Comput Assist Tomogr 2013 Jul-Aug;37(4):551-9

Department of Radiology, Mayo Clinic, Rochester, MN 55905, USA.

Objective: The objective of this study was to analyze radiation dose reduction and image quality by combining automated kV selection, tube current reduction, and iterative reconstruction.

Methods: This was a retrospective analysis of the excretory phase of 55 patients with 2 computed tomography urography examinations: automated kV selection with tube current reduction ("low-dose protocol": with filtered back projection vs iterative reconstruction) and routine dose examinations. Image quality was analyzed blindly and in side-by-side analyses, in addition to quantitative measurements.

Results: Low-dose protocol median dose change was -40% (-10.7 to +12.9 mGy); 100 kV was autoselected in 44 (80%) of 55 patients (body mass index range, 19-36 kg/m) with mean dose reduction of 42.5%. Whereas up to 19% of low-dose images with filtered back projection were inferior by blinded review (P < 0.001), low-dose iterative reconstruction images were not rated inferior (P = 1.0).

Conclusions: The combination of iterative reconstruction, automated kV selection, and tube current reduction results in radiation dose reduction with preserved image quality and diagnostic confidence.
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http://dx.doi.org/10.1097/RCT.0b013e31828f871fDOI Listing
September 2013

Perineural spread of cervical cancer to the sciatic nerve.

Skeletal Radiol 2013 Nov 11;42(11):1627-31. Epub 2013 Jun 11.

Department of Radiology, Mayo Clinic, Charlton 2-290, 200 First Street SW, Rochester, MN, 55905, USA,

In this report we present a patient with a recent diagnosis of cervical adenocarcinoma with progressive left lower extremity pain and weakness. MR imaging of the pelvis and subsequent FDG CT/PET were complementary in demonstrating abnormalities worrisome for perineural spread of malignancy, which was confirmed with an open fascicular biopsy of the sciatic nerve. We review the imaging and propose a mechanism of perineural spread to the sciatic nerve, which we believe is supported by the imaging in this case.
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http://dx.doi.org/10.1007/s00256-013-1653-0DOI Listing
November 2013

Choline PET/CT for imaging prostate cancer: an update.

Ann Nucl Med 2013 Aug 30;27(7):581-91. Epub 2013 Apr 30.

Department of Radiology, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan.

Whole-body positron emission tomography/computed tomography (PET/CT) with [(11)C]- and [(18)F]-labeled choline derivates has emerged as a promising molecular imaging modality for the evaluation of prostate cancer. (11)C- and (18)F-choline PET/CT are used successfully for restaging prostate cancer in patients with biochemical recurrence of disease after definitive therapy, especially when the serum prostate-specific antigen level is >1.0 ng/mL. (11)C- and (18)F-choline PET/CT have more limited roles for the initial staging of prostate cancer and for the detection of tiny lymph node metastases due to the low spatial resolution inherent to PET. Overall, these modalities are most useful in patients with a high pre-test suspicion of metastatic disease. The following is a review of the current clinical roles of (11)C- and (18)F-choline PET/CT in the management of prostate cancer.
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http://dx.doi.org/10.1007/s12149-013-0731-7DOI Listing
August 2013

Recurrent prostatic adenocarcinoma with perineural spread to the lumbosacral plexus and sciatic nerve: comparing high resolution MRI with torso and endorectal coils and F-18 FDG and C-11 choline PET/CT.

Abdom Imaging 2013 Oct;38(5):1155-60

Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, 55905, USA.

We present a patient with unexplained sciatica (radiating pain down the leg) found to have recurrent prostate adenocarcinoma within the sciatic nerve. High resolution MRI, especially use of an endorectal coil, improved visualization of the perineural spread of the disease. We believe that perineural spread resulting in sciatic symptoms in patients with known prostate adenocarcinoma may be an under-recognized phenomenon. The use of non-invasive modalities, high resolution endorectal coil MRI, and C-11 choline PET/CT can assist in the diagnosis of these patients.
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http://dx.doi.org/10.1007/s00261-013-9991-xDOI Listing
October 2013

Prognostic value of 18F-fluorodeoxyglucose-positron emission tomography in patients with differentiated thyroid carcinoma and circulating antithyroglobulin autoantibodies.

Nucl Med Commun 2011 Apr;32(4):245-51

Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905, USA.

Objective: To explore the prognostic value of F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) in radioiodine-negative patients with differentiated follicular cell-derived thyroid carcinoma with circulating antithyroglobulin autoantibodies (TgAb).

Methods: We retrospectively reviewed cases of all patients with differentiated thyroid cancer and increased TgAb referred for FDG-PET at Mayo Clinic, Rochester, Minnesota, from August 2001 to December 2004. PET findings were compared with results of other imaging and laboratory studies. Follow-up information was recorded until 19 December 2009.

Results: Of the 17 patients identified, PET results were true positive in 10 and false negative in two. In eight of these 12 patients with confirmed residual or recurrent disease, the increased TgAb level persisted and the disease progressed. In four of the 12 patients, TgAb decreased or disappeared after further treatment. In five patients, no residual or recurrent disease was found during follow-up. PET results were true negative in these five patients; TgAb disappeared spontaneously in four of these patients.

Conclusions: Negative PET results were associated with the absence of active disease and disappearing TgAb over time. FDG-avid residual lesions were associated with more aggressive disease and persistently increased TgAb.
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http://dx.doi.org/10.1097/MNM.0b013e328343a742DOI Listing
April 2011

The prognostic value of 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography in patients with suspected residual or recurrent medullary thyroid carcinoma.

Mol Imaging Biol 2010 Oct 1;12(5):547-53. Epub 2009 Dec 1.

Division of Nuclear Medicine, Department of Radiology, The Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway.

Purpose: To explore the prognostic value of 2-deoxy-2-[18F]fluoro-D-glucose (FDG) positron emission tomography (PET) in patients with suspected residual or recurrent medullary thyroid carcinoma (MTC).

Procedures: This retrospective study included all patients with MTC examined with FDG-PET at Mayo Clinic, Rochester, Minnesota, from October 1999 to March 2008. The PET results were compared with other imaging studies and clinical findings, including carcinoembryonic antigen and calcitonin levels.

Results: Twenty-nine patients with MTC were included. PET was positive in 14 patients, with follow-up information for 11; six died from metastatic disease, four had disease progression, and one remained in stable condition. PET was negative in 15 patients, with follow-up for 12; one had recurrent disease, and 11 had no evidence of clinical disease. Calcitonin doubling time was shorter for PET-positive than for PET-negative patients.

Conclusion: FDG-PET has high prognostic value in patients with suspected residual or recurrent MTC.
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http://dx.doi.org/10.1007/s11307-009-0276-2DOI Listing
October 2010

18F-FDG PET and PET/CT in Burkitt's lymphoma.

Eur J Radiol 2010 Jul 27;75(1):e68-73. Epub 2009 Aug 27.

Division of Nuclear Medicine, Department of Radiology, Mayo Clinic, Rochester, MN, USA.

Objective: To explore the value of (18)F fluorodeoxy-glucose (FDG) positron emission tomography (PET) in Burkitt's lymphoma.

Methods: All Burkitt's lymphoma patients referred for FDG PET or FDG PET/computed tomography (CT) exams at our institution from June 2003 to June 2006 were included. Selected patients were followed and clinical information was reviewed retrospectively. Results from FDG PET-PET/CT, as blindly reviewed by a consensus of two experienced readers, were compared with the status of the disease as determined by other laboratory, clinical and imaging exams and clinical follow-up. FDG PET-PET/CT results were classified as true positive or negative and false positive or negative. The degree of FDG uptake in the positive lesions was semiquantified as maximum standard uptake value (SUVmax).

Results: Fifty-seven FDG PET-PET/CT exams were done in 15 patients. Seven exams were done for initial staging, 8 during and 14 after the completion of therapy, and 28 for disease surveillance. For nodal disease FDG PET-PET/CT was true positive in 8, true negative in 47 and false positive in 2 exams (sensitivity 100%, specificity 96%). For extranodal disease FDG PET-PET/CT was true positive in 6, true negative in 48 and false positive in 3 exams (sensitivity 100%, specificity 94%). The mean SUVmax for the positive nodal lesions was 15.7 (range 6.9-21.7, median 18.5) and for extranodal lesions was 14.2 (range 6.2-24.3, median 12.4).

Conclusions: FDG PET-PET/CT is sensitive for the detection of viable disease in Burkitt's lymphoma. Affected areas demonstrated high degree of uptake that was reversible upon successful implementation of treatment.
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http://dx.doi.org/10.1016/j.ejrad.2009.07.035DOI Listing
July 2010

Pretreatment with diphenoxylate hydrochloride/atropine sulfate (Lomotil) does not decrease physiologic bowel FDG activity on PET/CT scans of the abdomen and pelvis.

Mol Imaging Biol 2009 Mar-Apr;11(2):114-7. Epub 2008 Nov 27.

Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.

Purpose: Physiologic uptake of 2-[(18)F]-fluoro-2-deoxy-D: -glucose (FDG) by bowel can confound positron emission tomography/computed tomography (PET/CT) assessment for abdominal pathology, particularly within the bowel itself. We wished to determine if oral administration of the antimotility agent, Lomotil (5 mg diphenoxylate hydrochloride/0.05 mg atropine sulfate; G.D. Searle and Company, a division of Pfizer), prior to PET/CT scanning would reduce physiologic uptake of FDG by the small bowel and colon (lower gastrointestinal [GI] tract).

Procedures: Patients undergoing PET/CT scans for lymphoma were enrolled in a prospective, randomized, double-blinded study and received either 10 mL water (control group) or 10 mL Lomotil (experimental group) orally 30-60 min prior to scanning. Scans were reviewed independently by two blinded experienced readers and scored for the degree of FDG activity in the lower GI tract relative to liver activity.

Results: The administration of Lomotil prior to PET/CT scanning did not reduce physiologic FDG activity in the small bowel and colon. In contrast, increased radiotracer uptake by the lower GI tract was observed in the Lomotil group compared to the control group.

Conclusions: Pretreatment with Lomotil prior to PET/CT scanning confers no benefit toward the reduction of physiologic FDG uptake by the small bowel and colon.
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http://dx.doi.org/10.1007/s11307-008-0178-8DOI Listing
September 2009

18F-FDG PET in the management of patients with anaplastic thyroid carcinoma.

Thyroid 2008 Jul;18(7):713-9

Division of Nuclear Medicine, Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905, USA.

Background: Anaplastic thyroid carcinoma (ATC) is one of the most aggressive solid tumors in humans. The use of positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) in ATC has not been studied, and only a few case reports have been published. The objective of this study was to investigate the potential contribution of 18F-FDG PET to the clinical management of patients with ATC.

Methods: All patients with ATC studied with 18F-FDG PET from August 2001 through March 2007 were included. The PET results were correlated with computed tomography, ultrasound, magnetic resonance imaging, bone scan, histology, and clinical follow-up. The FDG uptake was semiquantified as maximum standard uptake value. Any change in the treatment plan as a direct result of the PET findings as documented in the clinical notes was recorded.

Results: Sixteen patients were included. True-positive PET findings were seen for all primary tumors, in all nine patients with lymph node metastases, in five out of eight patients with lung metastases, and in two patients with distant metastases other than lung metastases. In 8 of the 16 patients, the medical records reported a direct impact of the PET findings on the clinical management.

Conclusions: ATC demonstrates intense uptake on 18F-FDG PET images. In 8 of the 16 patients (50%), the medical records reported a direct impact of the PET findings on the management of the patient. PET may improve disease detection and have an impact on the management of patients with ATC relative to other imaging modalities.
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http://dx.doi.org/10.1089/thy.2007.0350DOI Listing
July 2008

18F-FDG PET/CT in primary central nervous system lymphoma in HIV-negative patients.

Nucl Med Commun 2007 Nov;28(11):834-41

Division of Nuclear Medicine, Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905, USA.

Objective: To determine the value of F-FDG PET/CT in the different manifestations of primary central nervous system lymphoma (PCNSL) in HIV-negative patients.

Methods: All PCNSL and HIV-negative patients referred for PET/CT in our institution from July 2001 to June 2006 were retrospectively studied. PET/CT examinations were reviewed by two experienced readers and evaluated for each possible anatomical site of nervous system involvement: cerebral, spinal/nerve and ocular. PET/CT results were characterized as true positive or negative and false positive or negative according to the status of the disease, which was determined after the evaluation of biopsies, laboratory, clinical and imaging examinations, and follow-up.

Results: Forty-two PET/CT examinations were carried out in 25 PCNSL patients. For intracerebral disease, PET/CT was true positive in 13 cases, true negative in 27 and false negative in two. For disease involving spinal cord and/or nerves, PET/CT was true positive in four cases, true negative in 37 and false negative in one. For ocular disease, PET was true positive in only one case and false negative in four. The sensitivity of PET/CT in detecting active disease in the brain was 87% (13/15), in the spine/nerves 80% (4/5), and in the eyes only 20% (1/5).

Conclusion: PET/CT seems to be sensitive for the detection of viable intracerebral as well as for spinal and peripheral nerve disease, but not for the detection of ocular involvement.
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http://dx.doi.org/10.1097/MNM.0b013e328264ae7fDOI Listing
November 2007

Clinical significance of diffusely increased 18F-FDG uptake in the thyroid gland.

J Nucl Med 2007 Jun 15;48(6):896-901. Epub 2007 May 15.

Division of Nuclear Medicine, Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905, USA.

Unlabelled: Our purpose was to determine the clinical significance of diffusely increased (18)F-FDG uptake in the thyroid gland as an incidental finding on PET/CT.

Methods: All patients who were found to have diffuse thyroid uptake on (18)F-FDG PET/CT in our institution between November 2004 and June 2006 were investigated and compared with an age- and sex-matched control group. The (18)F-FDG uptake in the thyroid was semiquantified using maximum standardized uptake value and correlated to the available serum thyroid-stimulating hormone (TSH) and thyroid peroxidase (TPO) antibody levels using regression analysis.

Results: Of the 4,732 patients, 138 (2.9%) had diffuse thyroid uptake. Clinical information was available for 133 of the 138 patients. Sixty-three (47.4%) had a prior diagnosis of hypothyroidism or autoimmune thyroiditis, of whom 56 were receiving thyroxine therapy. In the control group, consisting of 133 patients with no thyroid uptake, there were 13 (9.8%) with a prior diagnosis of hypothyroidism, 11 of whom were receiving thyroxine therapy. In the study group, 38 (28.6%) of 133 patients did not undergo any further investigation for thyroid disease, whereas 32 (24.1%) of 133 patients were examined for thyroid disease after PET. Nineteen were found with autoimmune thyroiditis or hypothyroidism, and replacement therapy was initiated in 12. No significant correlation was found between maximum standardized uptake value and TSH (P = 0.09) or TPO antibody (P = 0.68) levels.

Conclusion: The incidental finding of increased (18)F-FDG uptake in the thyroid gland is associated with chronic lymphocytic (Hashimoto's) thyroiditis and does not seem to be affected by thyroid hormone therapy. SUV correlated neither with the degree of hypothyroidism nor with the titer of TPO antibodies.
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http://dx.doi.org/10.2967/jnumed.106.039024DOI Listing
June 2007

The value of quantifying 18F-FDG uptake in thyroid nodules found incidentally on whole-body PET-CT.

Nucl Med Commun 2007 May;28(5):373-81

Division of Nuclear Medicine, Department of Radiology, Mayo Clinic, Rochester, MN 55905, USA.

Objective: To determine if quantification of [18F]fluorodeoxyglucose (18F-FDG) uptake in a thyroid nodule found incidentally on whole-body 18F-FDG positron emission tomography-computed tomography (PET-CT) can be used to discriminate between malignant and benign aetiology.

Methods: A retrospective review of all patients with focally high uptake in the thyroid as an incidental finding on 18F-FDG PET-CT from May 2003 through May 2006. The uptake in the nodules was quantified using the maximum standardized uptake value (SUVmax). The aetiology was determined by cytology and/or ultrasound, or on histopathology.

Results: Incidental focally high uptake was found in 79/7347 patients (1.1%). In 31/48 patients with adequate follow-up, a benign aetiology was determined. Median SUVmax for the benign group was 5.6, range 2.5-53. Malignancy was confirmed in 15/48 patients. The malignancies were papillary thyroid carcinoma in 12, metastasis from squamous cell carcinoma in one, and lymphoma in two. Median SUVmax for the malignant lesions was 6.4, range 3.5-16. Cytology suspicious for follicular carcinoma was found in 2/48 patients. No statistical difference (P=0.12) was found among the SUVmax between the benign and malignant groups.

Conclusion: Focally high uptake of 18F-FDG in the thyroid as an incidental finding occurred in 1.1% of the patients. Malignancy was confirmed or was suspicious in 17/48 (35%) of the patients that had adequate follow-up. There was no significant difference in the SUVmax between benign and malignant nodules.
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http://dx.doi.org/10.1097/MNM.0b013e3280964eaeDOI Listing
May 2007