Clinical applications of PET/MRI: current status and future perspectives

Fully integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) scanners have been available for a few years. Since then, the number of scanner installations and published studies have been growing. While feasibility of integrated PET/MRI has been demonstrated for many clinical and preclinical imaging applications, now those applications where PET/MRI provides a clear benefit in comparison to the established reference standards need to be identified. The current data show that those particular applications demanding multiparametric imaging capabilities, high soft tissue contrast and/or lower radiation dose seem to benefit from this novel hybrid modality. Promising results have been obtained in whole-body cancer staging in non-small cell lung cancer and multiparametric tumor imaging. Furthermore, integrated PET/MRI appears to have added value in oncologic applications requiring high soft tissue contrast such as assessment of liver metastases of neuroendocrine tumors or prostate cancer imaging. Potential benefit of integrated PET/MRI has also been demonstrated for cardiac (i.e., myocardial viability, cardiac sarcoidosis) and brain (i.e., glioma grading, Alzheimer’s disease) imaging, where MRI is the predominant modality. The lower radiation dose compared to PET/computed tomography will be particularly valuable in the imaging of young patients with potentially curable diseases. However, further clinical studies and technical innovation on scanner hard- and software are needed. Also, agreements on adequate refunding of PET/MRI examinations need to be reached. Finally, the translation of new PET tracers from preclinical evaluation into clinical applications is expected to foster the entire field of hybrid PET imaging, including PET/MRI

Is integrated 18F-FDG PET/MRI superior to 18F-FDG PET/CT in the differentiation of incidental tracer uptake in the head and neck area?

PURPOSE:We aimed to investigate the accuracy of 18F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (18F-FDG PET/MRI) compared with contrast-enhanced 18F-FDG PET/computed tomography (PET/CT) for the characterization of incidental tracer uptake in examinations of the head and neck.METHODS:A retrospective analysis of 81 oncologic patients who underwent contrast-enhanced 18F-FDG PET/CT and subsequent PET/MRI was performed by two readers for incidental tracer uptake. In a consensus reading, discrepancies were resolved. Each finding was either characterized as most likely benign, most likely malignant, or indeterminate. Using all available clinical information including results from histopathologic sampling and follow-up examinations, an expert reader classified each finding as benign or malignant. McNemar’s test was used to compare the performance of both imaging modalities in characterizing incidental tracer uptake.RESULTS:Forty-six lesions were detected by both modalities. On PET/CT, 27 lesions were classified as most likely benign, one as most likely malignant, and 18 as indeterminate; on PET/MRI, 31 lesions were classified as most likely benign, one lesion as most likely malignant, and 14 as indeterminate. Forty-three lesions were benign and one lesion was malignant according to the reference standard. In two lesions, a definite diagnosis was not possible. McNemar’s test detected no differences concerning the correct classification of incidental tracer uptake between PET/CT and PET/MRI (P = 0.125).CONCLUSION:In examinations of the head and neck area, incidental tracer uptake cannot be classified more accurately by PET/MRI than by PET/CT

Thoughts on “Estimation of radiation exposure of children undergoing superselective, intra-arterial chemotherapy for retinoblastoma treatment: Assessment of Local Diagnostic Reference Levels as a function of age, sex and interventional success”

<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>Many techniques for the surgical treatment of gynaecomastia have been reported to be effective with reasonable limited scar formation. The aim of this study was to develop a grade adopted algorithm for effective and scar sparing techniques in reconstruction of the male breast dependent on aetiology and grading.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>Operative techniques, results, rates of revisions and complications were recorded between 2006 and 2018 and results of 164 male patients were analysed, retrospectively. Skin resecting methods have been used in the earlier stage but were later replaced by minimal periareolar incisions and subcutaneous mastectomy. Resections were combined with ultrasound-assisted liposuction up to grade 2b and inferior pedicled breast reduction in 3rd degree gynaecomastias resulting in reduction of scars and effective removal of breast tissue.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Retrospective analysis showed that a periareolar mastopexy was used in 24% of patients with gynaecomastia grade I, IIa and IIb to reshape the breast after subcutaneous mastectomy in the early stage of this study from 2006 to 2010. With the established standardised use of ultrasound-assisted liposuction, only 2% of patients required a mastopexy in the following years. In grade 3 gynaecomastia, the classical approach resulting in an inverted t-scar was later abandoned for an approach with a periareolar and submammary scar and inferior dermoglandular flap. The rate of secondary surgery with the used techniques did not increase.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>When using standardised techniques in reshaping the male breast, an aesthetically pleasing and safe result can be achieved by scar sparing techniques in a safe single-stage procedure.</jats:p></jats:sec><jats:sec><jats:title>Level of evidence</jats:title><jats:p>Level IV, therapeutic study.</jats:p></jats:sec&gt

Molecular Research in Urology 2014: Update on PET/MR Imaging of the Prostate

This article gives an overview of recent publications and potential indications of Positron emission tomography/ Magnetic resonance (PET/MR) imaging of prostate cancer

Dual-energy CT of liver metastases in patients with uveal melanoma

Objective: To investigate the value of different kVp images of dual-energy CT (DECT) for the detection of liver metastases. Methods: 20 Patients with uveal melanoma were investigated with DECT of the liver. In each patient contrast-enhanced DECT imaging with arterial delay was performed. Number and size of metastases were documented on arterial phase 80-kVp images, virtual 120-kVp images and following angiographic images (DSA) as part of hepatic chemoperfusion. Attenuation of metastases and several anatomic regions, subjective (image noise, image quality) and objective (SNR, CNR) parameters were documented. Results: The mean number of liver metastases detected was significant higher on 80-kVp images than on virtual 120-kVp/DSA images (5.6 ± 2.1 vs. 4.1 ± 1.8/4.3 ± 1.6); (p 20 mm: 56 vs. 42, p 20 mm: 56 vs. 41, p 20 mm were measured statistically equally. Noise, SNR and CNR of 80 kVp images were higher compared to 120 kVp images. Image quality of 120 kVp images was higher compared to 80 kVp images. Conclusion: Low-kVp images of DECT datasets are more sensitive in detecting liver metastases of patients with uveal melanoma than virtual 120 kVp- and DSA images. Keywords: Dual energy CT, Liver, Uveal melanoma, Angiography, Stagin

Treatment response after radioembolisation in patients with hepatocellular carcinoma—An evaluation with dual energy computed-tomography

Purpose: The aim of this prospective study was to examine the diagnostic value of dual-energy CT (DECT) in the assessment of response of HCC after radioembolisation (RE). Material and methods: 40 HCC patients with 82 measurable target lesions were included in this study. At baseline and follow-up examination target lesions were evaluated with (IU), AASLD and Choi measurement criteria. Disease control was defined as the sum of complete response (CR), partial response (PR), progression disease (PD) and stable disease (SD). Results: With Choi and IU more patients were considered than PR and less than PD and SD. According to AASLD more patients were measured as SD and PD than PR. 26/40 patients were classified as PR with IU. In contrast measurements with AASLD in only 8/26 patients were also classified as PR. 6/12 SD patients measured with IU were measured as PD with AASLD. 4/26 patients classified with IU as PR were described as SD with CHOI, 10/14 SD patients measured with CHOI were SD according to IU, the other 4 patients were PR with IU. 2/4 PD patients according to CHOI were SD with IU. Conclusion: More patients by IU were classified as SD versus PD and PR versus SD. We attribute this to the more detailed consideration of the HU differences between the virtual native and contrast-enhanced series generated by DECT. Iodine uptake (IU) in HCC measured and visualized with DECT is a promising imaging method for the assessment of treatment response after radioembolisations. Key points: —dual energy CT of hypervascular tumors such as HCC allows to quantify contrast enhancement without native imaging.—this can be used to evaluate the therapy response after Radioembolization. Keywords: Liver, Radioembolisation, Dual energy, CT stagin