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Objective: To demonstrate the utility of deep learning enhancement (DLE) to achieve diagnostic quality low-dose positron emission tomography (PET)/magnetic resonance (MR) imaging., Methods: Twenty subjects with known Crohn disease underwent simultaneous PET/MR imaging after intravenous administration of approximately 185 MBq of 18F-fluorodeoxyglucose (FDG). Five image sets were generated: (1) standard-of-care (reference), (2) low-dose (ie, using 20% of PET counts), (3) DLE-enhanced low-dose using PET data as input, (4) DLE-enhanced low-dose using PET and MR data as input, and (5) DLE-enhanced using no PET data input. Image sets were evaluated by both quantitative metrics and qualitatively by expert readers., Results: Although low-dose images (series 2) and images with no PET data input (series 5) were nondiagnostic, DLE of the low-dose images (series 3 and 4) achieved diagnostic quality images that scored more favorably than reference (series 1), both qualitatively and quantitatively., Conclusions: Deep learning enhancement has the potential to enable a 90% reduction of radiotracer while achieving diagnostic quality images., Competing Interests: A.P. has received payments as consultant from Sanofi Genzyme. D.H.K. is a shareholder for Elucent and Cellectar. The University of Wisconsin-Madison Department of Radiology receives research support from GE Healthcare. The remaining authors declare no conflict of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: To investigate the use of a chemical shift-based water-fat separation magnetic resonance imaging (MRI) method, and time-resolved contrast-enhanced MRI at 3 T for improved presurgical localization of parathyroid adenomas., Methods: Twenty-five patients with primary hyperparathyroidism were prospectively enrolled. Patients underwent MRI, which was reviewed by two experienced neuroradiologists who were blinded to Tc-99m sestamibi imaging and operative results., Results: Overall, MRI detected 16 adenomas in 25 patients (sensitivity 64%, positive predictive value 67%), while sestamibi detected 18 of 25 adenomas (sensitivity 72%, positive predictive value 90%). Importantly, MRI was able to detect adenomas in four (57%) of the seven patients whose disease was missed by sestamibi analysis. MRI demonstrated excellent image quality and fat suppression by using a chemical shift-based water-fat separation technique. The time-resolved MRI was considered to be less helpful, although in some cases it was indispensable., Conclusions: MRI is an excellent adjunct for preoperative parathyroid localization. The advent of improved fat suppression techniques in the neck, including chemical shift-based water-fat separation, is critical to its utility. Although time-resolved MRI was not always helpful, it was crucial in certain cases. It may prove to be more useful with the development of faster scanning techniques.

Objectives: The goals of this work were (1) to determine the effect of [(18)F]fluorodeoxyglucose positron emission tomography (FDG-PET), MRI, and EEG on the decision to perform temporal lobe epilepsy (TLE) surgery, and (2) to determine if FDG-PET, MRI, or EEG predicts surgical outcome., Methods: All PET scans ordered (2000-2010) for epilepsy or seizures were tabulated. Medical records were investigated to determine eligibility and collect data. Statistical analysis included odds ratios, κ statistics, univariate analysis, and logistic regression., Results: Of the 186 patients who underwent FDG-PET, 124 had TLE, 50 were surgical candidates, and 34 had surgery with post-operative follow-up. Median length of follow-up was 24 months. MRI, FDG-PET, and EEG were significant predictors of surgical candidacy (P<0.001) with odds ratios of 42.8, 20.4, and 6.3, respectively. FDG-PET was the only significant predictor of postoperative outcome (P<0.01)., Conclusion: MRI showed a trend toward having the most influence on surgical candidacy, but only FDG-PET predicted surgical outcome., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Magnetic resonance (MR) and positron emission tomography (PET) imaging techniques were coregistered to demonstrate regional ventilation and inflammation in the lung for in vivo, noninvasive evaluation of regional lung function associated with allergic inflammation. Four Brown Norway rats were imaged pre- and post segmental allergen challenge using respiratory-gated He-3 magnetic resonance imaging (MRI) to visualize ventilation, T(1)-weighted proton MRI to depict inflammatory infiltrate, and [F-18]fluorodeoxyglucose-PET to detect regional glucose metabolism by inflammatory cells. Segmental allergen challenges were delivered and the pre- and postchallenge lung as well as the contralateral lung were compared. Coregistration of the imaging results demonstrated that regions of ventilation defects, inflammatory infiltrate, and increased glucose metabolism correlated well with the site of allergen challenge delivery and inflammatory cell recruitment, as confirmed by histology. This method demonstrates that fusion of functional and anatomic PET and MRI image data may be useful to elucidate the functional correlates of inflammatory processes in the lungs.

Objective. Manual analysis of individual cancer lesions to assess disease response is clinically impractical and requires automated lesion tracking methodologies. However, no methodology has been developed for whole-body individual lesion tracking, across an arbitrary number of scans, and acquired with various imaging modalities. Approach. This study introduces a lesion tracking methodology and benchmarked it using 23 68Ga-DOTATATE PET/CT and PET/MR images of eight neuroendocrine tumor patients. The methodology consists of six steps: (1) alignment of multiple scans via image registration, (2) body-part labeling, (3) automatic lesion-wise dilation, (4) clustering of lesions based on local lesion shape metrics, (5) assignment of lesion tracks, and (6) output of a lesion graph. Registration performance was evaluated via landmark distance, lesion matching accuracy was evaluated between each image pair, and lesion tracking accuracy was evaluated via identical track ratio. Sensitivity studies were performed to evaluate the impact of lesion dilation (fixed versus automatic dilation), anatomic location, image modalities (inter- versus intra-modality), registration mode (direct versus indirect registration), and track size (number of time-points and lesions) on lesion matching and tracking performance. Main results. Manual contouring yielded 956 lesions, 1570 lesion-matching decisions, and 493 lesion tracks. The median residual registration error was 2.5 mm. The automatic lesion dilation led to 0.90 overall lesion matching accuracy, and an 88% identical track ratio. The methodology is robust regarding anatomic locations, image modalities, and registration modes. The number of scans had a moderate negative impact on the identical track ratio (94% for 2 scans, 91% for 3 scans, and 81% for 4 scans). The number of lesions substantially impacted the identical track ratio (93% for 2 nodes versus 54% for ≥5 nodes). Significance. The developed methodology resulted in high lesion-matching accuracy and enables automated lesion tracking in PET/CT and PET/MR. [ABSTRACT FROM AUTHOR]

Purpose: There is a continuous search for imaging techniques with high sensitivity and specificity for brain tumors. Positron emission tomography (PET) imaging has shown promise, though many PET agents either have a low tumor specificity or impractical physical half-lives. [124I]CLR1404 is a small molecule alkylphosphocholine analogue that is thought to bind to plasma membrane lipid rafts and has shown high tumor-to-background ratios (TBR) in a previous pilot study in brain tumor patients. This study attempts to define the clinical value of [124I]CLR1404 PET/CT (aka CLR124).Procedures: Adult patients with new or suspected recurrence of high-grade primary or metastatic brain tumors (N = 27) were injected with [124I]CLR1404 followed by PET/CT at 6, 24, and 48 h. Standard uptake values (SUV) and TBR values were calculated for all time points. Uptake of [124I]CLR1404 was qualitatively assessed, compared with magnetic resonance imaging (MRI), and correlated with clinical outcome. Final diagnosis (N = 25) was established based on surgically resected tissue or long-term follow-up.Results: Positive uptake with high TBR was detected in all but one patient with a final diagnosis of primary/recurrent brain tumor (12/13) and in less than half of patients with treatment-related changes (5/12). Concordance between [124I]CLR1404 uptake and contrast enhancement on MRI was seen in < 40 %, with no concordance between T2-hyperintensities and uptake. No significant difference in overall outcome was found between patients with and without [124I]CLR1404 uptake.Conclusions: The uptake pattern in these patients suggests a very high sensitivity of [124I]CLR1404 PET/CT for diagnosing tumor tissue; however, tumor specificity needs to be further defined. Relative lack of concordance with standard MRI characteristics suggests that [124I]CLR1404 PET/CT provides additional information about brain tumors compared to MRI alone, potentially improving clinical decision-making. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: The goals of this work were (1) to determine the effect of [18F]fluorodeoxyglucose positron emission tomography (FDG-PET), MRI, and EEG on the decision to perform temporal lobe epilepsy (TLE) surgery, and (2) to determine if FDG-PET, MRI, or EEG predicts surgical outcome. Methods: All PET scans ordered (2000–2010) for epilepsy or seizures were tabulated. Medical records were investigated to determine eligibility and collect data. Statistical analysis included odds ratios, κ statistics, univariate analysis, and logistic regression. Results: Of the 186 patients who underwent FDG-PET, 124 had TLE, 50 were surgical candidates, and 34 had surgery with post-operative follow-up. Median length of follow-up was 24months. MRI, FDG-PET, and EEG were significant predictors of surgical candidacy (P <0.001) with odds ratios of 42.8, 20.4, and 6.3, respectively. FDG-PET was the only significant predictor of postoperative outcome (P <0.01). Conclusion: MRI showed a trend toward having the most influence on surgical candidacy, but only FDG-PET predicted surgical outcome. [Copyright &y& Elsevier]