Publications by authors named "Iris M Noebauer-Huhmann"

13 Publications

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Erratum: Soft Tissue Sarcoma Follow-up Imaging: Strategies to Distinguish Post-treatment Changes from Recurrence.

Semin Musculoskelet Radiol 2020 Dec 5;24(6):e1. Epub 2021 Jan 5.

Department of radiology, Leiden University Medical Center,Leiden, The Netherlands.

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http://dx.doi.org/10.1055/s-0040-1722295DOI Listing
December 2020

Therapy-Related Imaging Findings in Patients with Sarcoma.

Semin Musculoskelet Radiol 2020 Dec 11;24(6):676-691. Epub 2020 Dec 11.

Department of Biomedical Imaging and Image Guided Therapy, Medical University of Vienna, Vienna, Austria.

Knowledge of imaging findings related to therapy administered to patients with sarcoma is pivotal in selecting appropriate care for these patients. Imaging studies are performed as surveillance in asymptomatic patients or because symptoms, including anxiety, develop. In addition to detection of recurrent disease and assessment of response to therapy, diagnosis of conditions related to therapy that may or may not need treatment has a marked positive impact on quality of life. The purpose of this review is to assist radiologists, nuclear physicians, and others clinicians involved in the diagnosis and treatment of these patients in recognizing imaging findings related to therapy and not to activity of the previously treated sarcoma. Imaging findings are time dependent and often specific in relation to therapy given.
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http://dx.doi.org/10.1055/s-0040-1721097DOI Listing
December 2020

Soft Tissue Sarcoma Follow-up Imaging: Strategies to Distinguish Post-treatment Changes from Recurrence.

Semin Musculoskelet Radiol 2020 Dec 11;24(6):627-644. Epub 2020 Dec 11.

Department of radiology, Leiden University Medical Center, Leiden, The Netherlands.

Soft tissue sarcomas encompass multiple entities with differing recurrence rates and follow-up intervals. The detection of recurrences and their differentiation from post-therapeutic changes is therefore complex, with a central role for the clinical radiologist. This article describes approved recommendations. Prerequisite is a precise knowledge of the current clinical management and surgical techniques. We review recurrence rates and treatment modalities. An adequate imaging technique is paramount, and comparison with previous imaging is highly recommended. We describe time-dependent therapy-related complications on magnetic resonance imaging compared with the spectrum of regular post-therapeutic changes. Early complications such as seromas, hematomas, and infections, late complications such as edema and fibrosis, and inflammatory pseudotumors are elucidated. The appearance of recurrences and radiation-associated sarcomas is contrasted with these changes. This systematic approach in follow-up imaging of soft tissue sarcoma patients will facilitate the differentiation of post-therapeutic changes from recurrences.
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http://dx.doi.org/10.1055/s-0040-1721464DOI Listing
December 2020

Impact of concentration and dilution of three macrocyclic gadolinium-based contrast agents on MRI signal intensity at 1.5T and 3T and different pulse sequences: results of a phantom study in human plasma.

Acta Radiol 2021 Jan 14;62(1):51-57. Epub 2020 Apr 14.

Bayer AG, Berlin, Germany.

Background: Many factors influence the increase in signal intensity (SI) provided by magnetic resonance imaging (MRI) contrast media.

Purpose: To assess the impact of different gadolinium concentrations and dilutions of three macrocyclic gadolinium-based contrast agents (GBCA) on SI.

Material And Methods: This phantom study investigated gadobutrol, gadoteridol, and gadoterate in human plasma of a healthy donor pool at 37 °C. Different molar concentrations served to mimic conditions typically relevant for steady-state imaging; different dilutions served to mimic influence on first-pass bolus imaging. For SI measurement at 1.5T and 3T, we used two Magnetom Scanners (Siemens), applying the T1-weighted sequences Flash 2D/3D and VIBE. Regions of interest were placed on the central slice of the test vials.

Results: In the concentration series, gadobutrol showed the highest SI of all three GBCAs up to 2 mM, followed by gadoteridol and gadoterate. No major differences were seen between 1.5T and 3T. In the dilution series, gadobutrol showed the highest SI of all three GBCAs up to 10 mL/L. The highest effect was recorded with Flash 3D and VIBE at 3T.

Conclusion: SIs measured in phantoms using three macrocyclic GBCAs strongly depend on their relaxivity and on the local concentration. The latter can be influenced-when comparing dilutions-by their initial concentration in their formulation. Furthermore, the pulse sequences and the chosen parameters have essential influence. At steady-state concentrations (≤2 mM) and first-pass bolus dilutions (up to 10 ml/L), gadobutrol showed highest SIs, followed by gadoterate and gadoteridol.
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http://dx.doi.org/10.1177/0284185120915674DOI Listing
January 2021

Comparison of the Relaxivities of Macrocyclic Gadolinium-Based Contrast Agents in Human Plasma at 1.5, 3, and 7 T, and Blood at 3 T.

Invest Radiol 2019 09;54(9):559-564

Bayer AG, Berlin, Germany.

Purpose: The relaxivities of 3 macrocyclic gadolinium-based contrast agents (GBCAs) were determined in human plasma and blood under standardized and clinically relevant laboratory conditions.

Methods: The T1 relaxivity, r1, was determined in human plasma at 1.5, 3, and 7 T, and in human blood at 3 T at 37°C in phantoms containing 4 different concentrations of the macrocyclic GBCAs gadobutrol, gadoteridol, and gadoterate. An inversion recovery turbo spin echo sequence was used to generate images with several inversion times. The T1-times were obtained by fitting the signal intensities to the signal equation. r1 was obtained by a 1/y-weighted regression of the T1-rates over the concentration of the GBCAs.

Results: For gadobutrol, the obtained r1 [L/(mmol·s)] in human plasma at 1.5 T, 3 T, and 7 T, and in human blood at 3 T was 4.78 ± 0.12, 4.97 ± 0.59, 3.83 ± 0.24, and 3.47 ± 0.16. For gadoteridol, r1 was 3.80 ± 0.10, 3.28 ± 0.09, 3.21 ± 0.07, and 2.61 ± 0.16, and for gadoterate, 3.32 ± 0.13, 3.00 ± 0.13, 2.84 ± 0.09, and 2.72 ± 0.17.

Conclusions: The relaxivity of gadobutrol is significantly higher than that of gadoteridol and gadoterate at all magnetic field strengths and in plasma as well as in blood, whereas that of gadoteridol was higher than gadoterate only in plasma at 1.5 and 7 T. This is in accordance with results from 3 previous studies obtained in different media.
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http://dx.doi.org/10.1097/RLI.0000000000000577DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6738537PMC
September 2019

ESSR Consensus Document for Detection, Characterization, and Referral Pathway for Tumors and Tumorlike Lesions of Bone.

Semin Musculoskelet Radiol 2017 Nov 12;21(5):630-647. Epub 2017 Oct 12.

Institute of Diagnostic and Interventional Radiology, University Hospital Rostock, Rostock, Germany.

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http://dx.doi.org/10.1055/s-0037-1606130DOI Listing
November 2017

Soft Tissue Tumors in Adults: ESSR-Approved Guidelines for Diagnostic Imaging.

Semin Musculoskelet Radiol 2015 Dec 22;19(5):475-82. Epub 2015 Dec 22.

Department of Radiology, Leiden University Medical Center, the Netherlands.

Soft tissue sarcomas are rare, but early, accurate diagnosis with subsequent appropriate treatment is crucial for the clinical outcome. The ESSR guidelines are intended to help radiologists in their decision-making and support discussion among clinicians who deal with patients with suspected or proven soft tissue tumors. Potentially malignant lesions recognized by ultrasound should be referred for magnetic resonance imaging (MRI), which also serves as a preoperative local staging modality, with specific technical requirements and mandatory radiological report elements. Radiography may add information about matrix calcification and osseous involvement. Indeterminate lesions, or lesions in which therapy is dependent on histology results, should be biopsied. For biopsy, we strongly recommend referral to a specialist sarcoma center, where an interdisciplinary tumor group, with a specialized pathologist, radiologist, and the surgeon are involved. In sarcoma, a CT scan of the chest is mandatory. Additional staging modalities are entity-specific. There are no evidence-based recommendations for routine follow-up in surgically treated sarcomas. However, we would recommend regular follow-up with intervals dependent on tumor grade, for 10 years after the initial diagnosis.
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http://dx.doi.org/10.1055/s-0035-1569251DOI Listing
December 2015

Gadolinium-based magnetic resonance contrast agents at 7 Tesla: in vitro T1 relaxivities in human blood plasma.

Invest Radiol 2010 Sep;45(9):554-8

Department of Radiology, MR Centre- Highfield MR, Vienna, Austria.

Unlabelled: PURPOSE/INTRODUCTION: The aim of this study was to determine the T1 relaxivities (r1) of 8 gadolinium (Gd)-based MR contrast agents in human blood plasma at 7 Tesla, compared with 3 Tesla.

Subjects And Methods: Eight commercially available Gd-based MR contrast agents were diluted in human blood plasma to concentrations of 0, 0.25, 0.5, 1, and 2 mmol/L. In vitro measurements were performed at 37 degrees C, on a 7 Tesla and on a 3 Tesla whole-body magnetic resonance imaging scanner. For the determination of T1 relaxation times, Inversion Recovery Sequences with inversion times from 0 to 3500 ms were used. The relaxivities were calculated.

Results: The r1 relaxivities of all agents, diluted in human blood plasma at body temperature, were lower at 7 Tesla than at 3 Tesla. The values at 3 Tesla were comparable to those published earlier. Notably, in some agents, a minor negative correlation of r1 with a concentration of up to 2 mmol/L could be observed. This was most pronounced in the agents with the highest protein-binding capacity.

Discussion/conclusion: At 7 Tesla, the in vitro r1 relaxivities of Gd-based contrast agents in human blood plasma are lower than those at 3 Tesla. This work may serve as a basis for the application of Gd-based MR contrast agents at 7 Tesla. Further studies are required to optimize the contrast agent dose in vivo.
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http://dx.doi.org/10.1097/RLI.0b013e3181ebd4e3DOI Listing
September 2010

Unenhanced MDCT in patients with suspected urinary stone disease: do coronal reformations improve diagnostic performance?

AJR Am J Roentgenol 2007 Aug;189(2):W60-4

Department of Radiology, Medical University of Vienna, General Hospital of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria.

Objective: The objectives of our study were to assess whether coronal reformations improve the diagnostic performance of MDCT in patients with acute flank pain and suspected urinary stone disease; and to determine if performing such reformations from 3-mm-thick sections is sufficient or if it is necessary to perform reformations from thinner sections.

Materials And Methods: We included 147 consecutive patients (72 women and 75 men; mean age +/- SD, 58 +/- 18.1 years) with suspected urinary stone disease who underwent unenhanced MDCT. Scans were obtained with a 4 x 1 mm collimation and were reconstructed with a section thickness of 1.25 and 3 mm. We compared the diagnostic yield of 3-mm axial sections with that of coronal reformations reconstructed from 1.25- and 3-mm axial sections. Imaging data were evaluated in random order by two radiologists. The significance of the difference between the axial sections and coronal multiplanar reformations (MPRs) was tested for the number, size, and location of uroliths and for the presence of alternative diagnoses. The time required for review by both observers was recorded.

Results: We found uroliths in 72 patients. There was no difference between 3-mm axial sections and coronal reformations from 1.25-mm sections with regard to the number of detected stones (n = 264 for both protocols), whereas coronal reformations from 3-mm sections revealed significantly fewer calcifications (n = 255, p = 0.016). Coronal reformations did not improve the localization of calcifications. Review time, however, was significantly shorter for coronal reformations than for axial sections (p = 0.001); however, coronal reformations were less sensitive than axial sections for the detection of additional findings suggestive of alternative diagnoses in 16 (30%) of 53 patients.

Conclusion: Coronal reformations from MDCT do not improve urinary stone detection but may reduce evaluation time; however, there is the danger of missing additional findings. Coronal reformations reconstructed from thick (i.e., 3-5 mm) axial sections may result in reduced detection of small stones and should therefore be avoided.
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http://dx.doi.org/10.2214/AJR.07.2199DOI Listing
August 2007

Improved preoperative evaluation of cerebral cavernomas by high-field, high-resolution susceptibility-weighted magnetic resonance imaging at 3 Tesla: comparison with standard (1.5 T) magnetic resonance imaging and correlation with histopathological findings--preliminary results.

Invest Radiol 2007 Jun;42(6):346-51

MR Centre of Excellence, Department of Radiology, Medical University Vienna, Vienna, Austria.

Objectives: To compare high-field, high-resolution, susceptibility-weighted magnetic resonance imaging (3 Tesla [T] HR-SW-MRI) and standard (1.5 Tesla [T]) MRI for the detection of cerebral cavernomas. To evaluate the ability of 3 T HR-SW-MRI to visualize intralesional structures compared with standard (1.5 T) MRI, in correlation with histopathologic findings.

Materials And Methods: Seventeen patients with cerebral cavernomas underwent both standard (1.5 T) MRI (T1-SE, T2-TSE, T2*-GRE) and 3 T HR-SW-MRI (TR/TE 43.3/9.1 millisecond; 512 x 384 x 48 matrix; FOV 250 mm; SI 72 mm) at our institution. All MR images were evaluated by 3 radiologists in consensus for detectability, size (1 cm), and conspicuity (good, acceptable, poor) of the lesions at both field strengths, and for the presence of hypointense intralesional tubular structures. In 7 patients, MR findings were correlated with histopathologic findings.

Results: Both 3 T HR-SW-MRI and standard (1.5 T) MRI detected 22 lesions in 17 patients; 3 T HR-SW-MRI detected an additional 7 lesions in 6 patients. On average, 3 T HR-SW-MRI detected 1.706 +/- 0.92 (median = 1) lesions per patient, whereas standard (1.5 T) MRI detected 1.235 +/- 0.664 lesions per patient (P = 0.016). Lesion conspicuity was good in all 3 T HR-SW-MR images and good in 68.2% and acceptable in 31.8% of standard (1.5 T) MR images (P = 0.016). In 22 lesions detected at both field strengths, 3 T HR-SW-MRI demonstrated intralesional tubular structures in 72.7% and standard (1.5 T) MRI demonstrated these structures in 31.8% (P = 0.001). Intralesional tubular structure correlated to conglomerates of cavernous vessel, as verified by histopathology.

Conclusion: Compared with standard (1.5 T) MRI, 3 T HR-SW-MRI allows superior detection and characterization of cerebral cavernomas. Despite increased susceptibility effects, ie, signal loss at higher magnetic field strengths, the visualization of intralesional tubular structures is feasible. This may be helpful in the diagnosis, presurgical planning, and noninvasive follow-up after gamma-knife radiosurgery.
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http://dx.doi.org/10.1097/01.rli.0000262744.85397.fcDOI Listing
June 2007

MR imaging of the cervical spine: assessment of image quality with parallel imaging compared to non-accelerated MR measurements.

Eur Radiol 2007 May 27;17(5):1147-55. Epub 2006 Oct 27.

Department of Radiology, Medical University of Vienna, Waehringer Gürtel 18-20, 1090, Vienna, Austria.

To compare the quality of cervical spine MR images obtained by parallel imaging [generalized autocalibrating partially parallel acquisition (GRAPPA)] with those of non-accelerated imaging, we conducted both phantom studies and examinations of ten volunteers at 1.5Tesla with a dedicated 12-element coil system and a head-spine-neck coil combination. Acquisitions included axial T2-weighted (T2w) images with both methods, and sagittal T2w and T1w images in vivo with the latter coil combination. Non-accelerated MRI with two averages and GRAPPA (acceleration factor 2) with two averages (GRAPPA/2AV, time reduction of approximately 50%) and four averages (GRAPPA/4AV) were compared. In the phantom, the signal-to-noise ratio of the GRAPPA/2AV was lower than that of the other two settings. In vivo, the image inhomogeneity (non-uniformity, NU) was significantly higher in T2w GRAPPA/2AV than in both other settings, and in T1w GRAPPA/2AV compared to GRAPPA/4AV. Subjectively, the delineation of anatomical structures was sufficient in all sequences. Only the spinal cord was considered to be better delineable on the non-accelerated T1w sequence compared to GRAPPA/2AV. In part, GRAPPA/4AV performed better than the other settings. The subjective image noise was lowest with GRAPPA/4AV. In cervical spine MRI, the examination time can be reduced by nearly 42% with GRAPPA, while preserving sufficient image quality.
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http://dx.doi.org/10.1007/s00330-006-0411-2DOI Listing
May 2007

Imaging articular cartilage defects in the ankle joint with 3D fat-suppressed echo planar imaging: comparison with conventional 3D fat-suppressed gradient echo imaging.

J Magn Reson Imaging 2002 Aug;16(2):209-16

Department of Radiology, University of Vienna, Vienna, Austria.

Purpose: To shorten the examination time for articular cartilage imaging, using a recently developed three-dimensional (3D) multishot echo planar imaging (EPI) sequence with fat saturated (FS), compared to a conventional 3D fat-saturated spoiled gradient echo sequence (3D FS GRE).

Material And Methods: There were 32 consecutive patients with ankle joint disorders who underwent magnetic resonance imaging (MRI) in a 1.0-T unit. Hyaline cartilage was imaged with a 3D FS EPI sequence and a 3D FS GRE sequence. Image assessment criteria included lesion conspicuity, contrast between different types of normal tissue, and image artifacts. In addition, contrast-to-noise ratios (CNRs) of cartilage vs. joint fluid and bone marrow were measured.

Results: The 3D FS EPI sequence provided a high CNR between cartilage and subchondral bone, similar to that of the 3D FS GRE sequence. The CNR between cartilage and effusion was significantly lower on the 3D EPI sequence due to the higher signal intensity of fluid. Both sequences were equal in lesion detection ability. The image quality of the 3D FS GRE sequence was slightly higher than that of the 3D FS EPI, but the difference was not statistically significant.

Conclusion: We conclude that the 3D FS EPI sequence is comparable to the 3D FS GRE sequence in the detection of cartilage lesions, with the additional advantage of reduction in scan time by a factor of 4.
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http://dx.doi.org/10.1002/jmri.10153DOI Listing
August 2002