Chest CT Findings in Marijuana Smokers.

Background Global consumption of marijuana is increasing, but there is a paucity of evidence concerning associated lung imaging findings. Purpose To use chest CT to investigate the effects of marijuana smoking in the lung. Materials and Methods This retrospective case-control study evaluated results of chest CT examinations (from October 2005 to July 2020) in marijuana smokers, nonsmoker control patients, and tobacco-only smokers. We compared rates of emphysema, airway changes, gynecomastia, and coronary artery calcification. Age- and sex-matched subgroups were created for comparison with tobacco-only smokers older than 50 years. Results were analyzed using χ2 tests. Results A total of 56 marijuana smokers (34 male; mean age, 49 years ± 14 [SD]), 57 nonsmoker control patients (32 male; mean age, 49 years ± 14), and 33 tobacco-only smokers (18 male; mean age, 60 years ± 6) were evaluated. Higher rates of emphysema were seen among marijuana smokers (42 of 56 [75%]) than nonsmokers (three of 57 [5%]) (P < .001) but not tobacco-only smokers (22 of 33 [67%]) (P = .40). Rates of bronchial thickening, bronchiectasis, and mucoid impaction were higher among marijuana smokers compared with the other groups (P < .001 to P = .04). Gynecomastia was more common in marijuana smokers (13 of 34 [38%]) than in control patients (five of 32 [16%]) (P = .039) and tobacco-only smokers (two of 18 [11%]) (P = .040). In age-matched subgroup analysis of 30 marijuana smokers (23 male), 29 nonsmoker control patients (17 male), and 33 tobacco-only smokers (18 male), rates of bronchial thickening, bronchiectasis, and mucoid impaction were again higher in the marijuana smokers than in the tobacco-only smokers (P < .001 to P = .006). Emphysema rates were higher in age-matched marijuana smokers (28 of 30 [93%]) than in tobacco-only smokers (22 of 33 [67%]) (P = .009). There was no difference in rate of coronary artery calcification between age-matched marijuana smokers (21 of 30 [70%]) and tobacco-only smokers (28 of 33 [85%]) (P = .16). Conclusion Airway inflammation and emphysema were more common in marijuana smokers than in nonsmokers and tobacco-only smokers, although variable interobserver agreement and concomitant cigarette smoking among the marijuana-smoking cohort limits our ability to draw strong conclusions. © RSNA, 2022 See also the editorial by Galvin and Franks in this issue.

Case 307.

HISTORY: A 45-year-old woman presented to the emergency department with acute worsening of prolonged unexplained nausea, nonbilious vomiting, and mild upper abdominal pain of 4 years duration. Her bowel habits were regular, and there was no history of diarrhea or fresh or altered blood in her stool. On further inquiry, there was no history of facial flushing, excessive diaphoresis, or asthmalike symptoms. Her history was unrevealing; in particular, there was no history of known malignancy. On clinical examination, her vital signs were stable. The abdomen was soft, with no focal tenderness or palpable mass. Routine blood investigations, including complete blood counts, and liver, kidney, and thyroid function tests yielded results that were within normal limits. Her 5-hydroxyindoleacetic acid and chromogranin A levels were not elevated. Initial evaluation with contrast-enhanced CT of the abdomen and pelvis was performed. Subsequently, an indium 111 octreotide scan was performed at the recommendation of the radiologist 1 month after CT (Figs 1, 2).

Case 307: Heterotopic Pancreas in Jejunal Mesentery.

HISTORY: A 45-year-old woman presented to the emergency department with acute worsening of prolonged unexplained nausea, nonbilious vomiting, and mild upper abdominal pain of 4 years duration. Her bowel habits were regular, and there was no history of diarrhea or fresh or altered blood in her stool. On further inquiry, there was no history of facial flushing, excessive diaphoresis, or asthmalike symptoms. Her history was unrevealing; in particular, there was no history of known malignancy. On clinical examination, her vital signs were stable. The abdomen was soft, with no focal tenderness or palpable mass. Routine blood investigations, including complete blood counts, and liver, kidney, and thyroid function tests yielded results that were within normal limits. Her 5-hydroxyindoleacetic acid and chromogranin A levels were not elevated. Initial evaluation with contrast-enhanced CT of the abdomen and pelvis was performed. Subsequently, an indium 111 (111In) octreotide scan was performed at the recommendation of the radiologist 1 month after CT.

Utility of Quantitative T2-Mapping Compared to Conventional and Advanced Diffusion Weighted Imaging Techniques for Multiparametric Prostate MRI in Men with Hip Prosthesis.

BACKGROUND: Diffusion weighted imaging (DWI) is fundamental for prostate cancer (PCa) detection with MRI; however, limited by susceptibility artifact from hip prosthesis. PURPOSE: To evaluate image quality and ability to detect PCa with quantitative T2-mapping and DWI in men with hip prosthesis undergoing prostate MRI. STUDY TYPE: Prospective, cross-sectional study. POPULATION: Thirty consecutive men with hip replacement (18 unilateral, 12 bilateral) undergoing prostate MRI from 2019 to 2021. FIELD STRENGTH/SEQUENCE: 3-T; multiparametric MRI (T2W, DCE-MRI, echo-planar [EPI]-DWI), T2-mapping (Carr-Purcell-Meiboom-Gill), FOCUS-EPI-DWI, PROPELLER-DWI. ASSESSMENT: Five blinded radiologists independently evaluated MRI image quality using a 5-point Likert scale. PI-RADS v2.1 scores were applied in four interpretation strategies: 1) T2W-FSE+DCE-MRI+EPI-DWI, 2) T2W-FSE+DCE-MRI+EPI-DWI+FOCUS-EPI-DWI, 3) T2W-FSE+DCE-MRI+EPI-DWI+PROPELLER-DWI, 4) T2W-FSE+DCE-MRI+EPI-DWI+T2-maps. Five-point confidence scores were recorded. STATISTICAL ANALYSIS: ANOVA, Kruskal-Wallis with pair-wise comparisons by Wilcoxon sign-rank, and paired t-tests, P < 0.05 was considered significant. Cohen's Kappa (k) for PI-RADSv2.1 scoring and proportion of correctly classified lesions tabulated for pathology-confirmed cases with 95% confidence intervals (CIs). RESULTS: For all radiologists, T2-map image quality was significantly higher than EPI-DWI, FOCUS-EPI-DWI, and PROPELLER-DWI and similar (P = 0.146-0.706) or significantly better (for two readers) than T2W-FSE and DCE-MRI. PI-RADS v2.1 agreement improved comparing strategy A (k = 0.46) to strategy B (k = 0.58) to strategy C (k = 0.58) and was highest with strategy D which included T2-maps (k = 1.00). Radiologists' confidence was significantly highest with strategy D. Strategies B and C had similar confidence (P = 0.051-0.063) both significantly outperforming strategy A. Twelve men with 17 lesions had pathology confirmed diagnoses (13 PCa, 4 benign). Strategy D had the highest proportion of correctly classified lesions (76.5-82.4%) with overlapping 95% confidence intervals. DATA CONCLUSION: T2-mapping may be a valuable adjunct to prostate MRI in men with hip replacement resulting in improved image quality, higher reader confidence, interobserver agreement, and accuracy in PI-RADS scoring. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 2.

Direct Comparison of Diagnostic Accuracy of Fast Kilovoltage Switching Dual-Energy Computed Tomography and Magnetic Resonance Imaging for Detection of Enhancement in Renal Masses.

PURPOSE: The aim of the study was to compare diagnostic accuracy of dual-energy computed tomography (DECT) and magnetic resonance imaging (MRI) to detect enhancement in renal masses. METHODS: Adults renal masses of 10 mm or greater with both fast kilovoltage potential switching DECT and contrast-enhanced MRI performed within 12 months were retrospectively included. Two blinded radiologists independently evaluated for enhancement subjectively (5-point Likert scales) and quantitatively (signal intensity ratio ≥15% for MRI, iodine concentration ≥1.2 or ≥2.0 mg/mL for DECT). Per-lesion diagnostic accuracy, with histologic reference standard for solid masses, was expressed as the area under the receiver operator curve (AUC) for each index test. Differences were evaluated for statistical significance using the DeLong test. RESULTS: We included 24 patients with 41 masses: 17 solid renal masses and 24 Bosniak 1 or 2 cysts. There was no significant difference in diagnostic accuracy comparing subjective enhancement by MRI and using iodine overlay DECT for reader 1 (AUC 0.99 vs 0.99, P = 0.38) or reader 2 (AUC 1.00 vs 0.94, P = 0.12) Interobserver agreement was κ = 0.61 for DECT and κ = 0.71 for MRI. There was no significant difference either in accuracy between quantitative assessment using signal intensity ratio or iodine concentration for reader 1 (AUC 0.94 vs 0.94, P = 0.88) or reader 2 (AUC 0.97 vs 0.92, P = 0.16). False-negative results in both subjective and quantitative assessment were nearly exclusively seen in papillary renal cell carcinoma, occurring with both DECT and MRI. CONCLUSIONS: We detected no significant differences in accuracy for detecting enhancement in renal masses comparing MRI and DECT. Our results require further investigation in larger sample sizes, but suggest that DECT may be comparable to MRI for detection of enhancement in renal masses.

Evaluation of a deep learning method for the automated detection of supraspinatus tears on MRI.

OBJECTIVE: To evaluate if deep learning is a feasible approach for automated detection of supraspinatus tears on MRI. MATERIALS AND METHODS: A total of 200 shoulder MRI studies performed between 2015 and 2019 were retrospectively obtained from our institutional database using a balanced random sampling of studies containing a full-thickness tear, partial-thickness tear, or intact supraspinatus tendon. A 3-stage pipeline was developed comprised of a slice selection network based on a pre-trained residual neural network (ResNet); a segmentation network based on an encoder-decoder network (U-Net); and a custom multi-input convolutional neural network (CNN) classifier. Binary reference labels were created following review of radiologist reports and images by a radiology fellow and consensus validation by two musculoskeletal radiologists. Twenty percent of the data was reserved as a holdout test set with the remaining 80% used for training and optimization under a fivefold cross-validation strategy. Classification and segmentation accuracy were evaluated using area under the receiver operating characteristic curve (AUROC) and Dice similarity coefficient, respectively. Baseline characteristics in correctly versus incorrectly classified cases were compared using independent sample t-test and chi-squared. RESULTS: Test sensitivity and specificity of the classifier at the optimal Youden's index were 85.0% (95% CI: 62.1-96.8%) and 85.0% (95% CI: 62.1-96.8%), respectively. AUROC was 0.943 (95% CI: 0.820-0.991). Dice segmentation accuracy was 0.814 (95% CI: 0.805-0.826). There was no significant difference in AUROC between 1.5 T and 3.0 T studies. Sub-analysis showed superior sensitivity on full-thickness (100%) versus partial-thickness (72.5%) subgroups. DATA CONCLUSION: Deep learning is a feasible approach to detect supraspinatus tears on MRI.

Comparison of 5 Rectal Preparation Strategies for Prostate MRI and Impact on Image Quality.

PURPOSE: To compare 5 different rectal preparation strategies for prostate MRI. METHODS: This 5-arm quality-assurance study evaluated 56 patients per arm (280 patients) including: no preparation, clear-fluids diet (CFD) beginning at 00:00 hours on the day of MRI, Fleet®-enema, enema + CFD, enema + CFD + IV-antispasmodic agent. The study was powered to 0.80 with alpha-error of 0.05. Three blinded radiologists independently evaluated T2-Weighted (T2W) and Diffusion Weighed Imaging (DWI) for: rectal diameter (maximal AP diameter), rectal content (stool, fluid, gas), rectal motion, T2W/DWI image quality, T2W image sharpness and DWI susceptibility artifact using 5-point Likert scales. Overall comparisons were performed using analysis of variance (ANOVA) and Kruskal-Wallis, with pair-wise comparisons using paired t-tests and Wilcoxon sign-rank tests. RESULTS: Rectal diameter and amount of gas were lower in enema compared to non-enema groups (p < 0.001), with smallest diameter and least gas in the enema + CFD + IV-antispasmodic group (p = 0.022-<0.001). T2W image quality and sharpness were highest in the enema + CFD groups (p < 0.001) with no difference comparing enema + CFD with/without IV-antispasmodic (p = 0.064, 0.084). Motion artifact was least in enema + CFD + IV-antispasmodic group compared to all other groups (p < 0.001), followed by the enema + CFD group (p = 0.008-<0.001). DWI image quality was highest (p < 0.001) and DWI susceptibility artifact lowest (p < 0.001) in the enema + CFD groups (p < 0.001) and did not differ comparing enema + CFD with/without anti-spasmodic (p = 0.058-0.202). CONCLUSIONS: Use of enema + clear-fluids diet before prostate MRI yields the highest T2W and DWI image quality with the least DWI artifact. IV-antispasmodic use reduces motion on T2W but does not improve image quality on T2W or DWI, or lessen DWI artifact compared to enema + clear-fluids diet.

A review of imaging of surface sarcomas of bone.

Surface lesions of bone are uncommon. Although their imaging features generally mirror those of their intramedullary counterparts, surface lesions may demonstrate distinct characteristics which along with their unusual location present a diagnostic challenge. Surface sarcomas are usually of a lower grade compared with intramedullary variants, leading to differences in management. Osteosarcoma arising from the cortical surface of the bone is termed juxtacortical or surface osteosarcoma and includes three distinct entities: parosteal, periosteal, and high-grade surface osteosarcoma. We also review the features intracortical osteosarcoma, which some authors include under the umbrella term surface osteosarcoma. These lesions exhibit biologic features distinct from those of conventional intramedullary osteosarcoma, which underlines the importance of accurate imaging diagnosis. Periosteal chondrosarcoma and periosteal Ewing sarcoma also have distinctive imaging appearances. The purpose of this article is to review surface sarcomas of bone with regard to their clinical and radiological features and to discuss the differential diagnosis for each condition.

Multidetector Computed Tomography in Traumatic and Nontraumatic Aortic Emergencies: Emphasis on Acute Aortic Syndromes.

Aortic emergencies comprise of a list of conditions which are uncommon but are potentially fatal. Prognosis is usually determined by emergent diagnosis and treatment and hence radiology plays a key role in patient management. In this article, we aim to review the various causes of aortic emergencies and the relevant imaging findings placing special emphasis on acute aortic syndromes.

Giant-cell tumor of the patella in a skeletally immature girl.

BACKGROUND: We reported on a case of a giant-cell tumor of the patella which occurred in a skeletally immature patient. This combination of unusual age of presentation and atypical location made our case clinically and radiologically unique. CASE REPORT: A 13-year-old girl presented with complains of knee pain and swelling. After radiological investigations and percutaneous needle biopsy a diagnosis of giant-cell tumor of the patella was made, for which the patient underwent patellectomy with en bloc resection of the lesion and the diagnosis was confirmed by histopathological examination. CONCLUSIONS: It was concluded that early diagnosis may be difficult in such cases and hence, GCT should be considered in the differential diagnosis of a destructive lesion of the patella, regardless of the age of presentation.

Machine learning based prediction of image quality in prostate MRI using rapid localizer images.

Purpose: Diagnostic performance of prostate MRI depends on high-quality imaging. Prostate MRI quality is inversely proportional to the amount of rectal gas and distention. Early detection of poor-quality MRI may enable intervention to remove gas or exam rescheduling, saving time. We developed a machine learning based quality prediction of yet-to-be acquired MRI images solely based on MRI rapid localizer sequence, which can be acquired in a few seconds. Approach: The dataset consists of 213 (147 for training and 64 for testing) prostate sagittal T2-weighted (T2W) MRI localizer images and rectal content, manually labeled by an expert radiologist. Each MRI localizer contains seven two-dimensional (2D) slices of the patient, accompanied by manual segmentations of rectum for each slice. Cascaded and end-to-end deep learning models were used to predict the quality of yet-to-be T2W, DWI, and apparent diffusion coefficient (ADC) MRI images. Predictions were compared to quality scores determined by the experts using area under the receiver operator characteristic curve and intra-class correlation coefficient. Results: In the test set of 64 patients, optimal versus suboptimal exams occurred in 95.3% (61/64) versus 4.7% (3/64) for T2W, 90.6% (58/64) versus 9.4% (6/64) for DWI, and 89.1% (57/64) versus 10.9% (7/64) for ADC. The best performing segmentation model was 2D U-Net with ResNet-34 encoder and ImageNet weights. The best performing classifier was the radiomics based classifier. Conclusions: A radiomics based classifier applied to localizer images achieves accurate diagnosis of subsequent image quality for T2W, DWI, and ADC prostate MRI sequences.

Inter-individual comparison of diagnostic accuracy of adrenal washout CT compared to chemical shift MRI plus the T2-weighted (T2W) adrenal MRI calculator in indeterminate adrenal masses: a retrospective non-inferiority study.

OBJECTIVE: To compare diagnostic accuracy of washout (WO)-CT to chemical shift (CS)-MRI + T2W adrenal MRI Calculator (T2W-Calculator) to diagnose adrenal adenoma in indeterminate adrenal masses. METHODS: This retrospective, cross-sectional, non-inferiority study evaluated 40 consecutive indeterminate adrenal masses; each with WO-CT and MRI. Two blinded radiologists independently evaluated in mixed order: pre-contrast attenuation (Hounsfield Units, HU) and absolute WO ([Peak.HU-Delay.HU]/[Peak.HU-Pre.HU] × 100%), Chemical Shift Signal Intensity (CS-SI) Index, T2W SI ratio, and Entropy (which were imputed into the T2W-Calculator). Diagnostic accuracy for adrenal adenoma was tabulated using 2 × 2 tables. True -positive diagnoses of adenoma were CT = Pre-HU < 10 or absolute WO ≥ 60%, MRI = SI index ≥ 16.5% or T2W-Calculator < 0.631. RESULTS: There were 73% (29/40) adenomas and 27% (11/40) other masses (5 pheochromocytoma, 3 solitary fibrous tumor, 1 metastasis, 1 cavernous hemangioma, and 1 adrenocortical carcinoma). Sensitivity, specificity, and accuracy for diagnosis of adenoma using CT-WO were 78% (95% confidence intervals [CI] 56-93%), 35% (14-62%), and 57% (42-71%) Reader 1 and 72% (53-87%), 46% (17-77%), and 59% (41-76%) Reader 2. Sensitivity, specificity, and accuracy for diagnosis of adenoma using MRI were 100% (88-100%), 64% (34-90%), and 82% (67-97%) Reader 1 and 86% (68-96%), 73% (39-94%), and 80% (64-95%) Reader 2. MRI had higher overall accuracy (p = 0.02 Reader 1, 0.05 Reader 2) compared to CT-WO. CONCLUSION: Chemical shift MRI combined with the T2W adrenal MRI calculator is not inferior to CT Washout for diagnosis of adrenal adenoma among indeterminate adrenal masses.

Risk of nephrogenic systemic fibrosis (NSF) in oncology patients receiving gadoxetic acid and updated risk of estimate of NSF in patients receiving gadoxetic acid with moderate and severe renal impairment.

OBJECTIVES: Gadoxetic acid (GA) is a half-biliary excreted gadolinium-based contrast agent (GBCA) administered at lower dose than gadobenic acid with similar ionic structure. Gadobenic acid is considered low-risk for nephrogenic systemic fibrosis (NSF) in patients with impaired renal function; however, safety of GA is unclear. The objective of this study was to determine the incidence of NSF in oncology patients undergoing GA-enhanced MRI and to update the risk estimate of NSF in patients receiving GA with severe renal impairment. MATERIALS AND METHODS: We retrospectively identified GA-enhanced MRI performed for treatment planning in confirmed cancer patients between March 2011 and December 2020. Serum creatinine values within 180 days of GA administration were retrieved and estimated glomerular filtration rate (eGFR) calculated. The eGFR value nearest to each MRI examination was used. The search result was linked to a prospectively maintained registry of reported cases of NSF. An updated literature review was conducted to identify published cases of NSF related to GA administration in patients with severe renal impairment (eGFR < 30 mL/min/1.73 m2 or on dialysis) and the incidence of NSF with 95% confidence intervals (CI) was determined combining published data with our results. RESULTS: 192 oncology patients underwent GA-enhanced MRI, mean age was 65.6 ± 11.8 years with 73 women. The mean eGFR was 89.6 ± 33.0 mL/min/1.73 m2. There were 33 patients with moderate (eGFR 30-60 mL/min/1.73 m2) and 1 patient with severe (eGFR < 30 mL/min/1.73 m2) renal impairment. There were no reported cases of NSF. Updated literature review including our results identified 340 patients with severe renal impairment or on dialysis with zero cases of NSF (0/340; 95% confidence intervals 0% and 0.9%). CONCLUSION: No cases of NSF were documented in this study related to gadoxetic acid use in oncology patients, including those with moderate and severe renal impairment. Recent data indicate use of gadoxetic acid in patients with renal impairment can be considered low-risk.

Imaging considerations for thermal and radiotherapy ablation of primary and metastatic renal cell carcinoma.

Ablative (percutaneous and stereotactic) thermal and radiotherapy procedures for management of both primary and metastatic renal cell carcinoma are increasing in popularity in clinical practice. Data suggest comparable efficacy with lower cost and morbidity compared to nephrectomy. Ablative therapies may be used alone or in conjunction with surgery or chemotherapy for treatment of primary tumor and metastatic disease. Imaging plays a crucial role in pre-treatment selection and planning of ablation, intra-procedural guidance, evaluation for complications, short- and long-term post-procedural surveillance of disease, and treatment response. Treatment response and disease recurrence may differ considerably after ablation, particularly for stereotactic radiotherapy, when compared to conventional surgical and chemotherapies. This article reviews the current and emerging role of imaging for ablative therapy of renal cell carcinoma.

Fully automated detection of prostate transition zone tumors on T2-weighted and apparent diffusion coefficient (ADC) map MR images using U-Net ensemble.

PURPOSE: Accurate detection of transition zone (TZ) prostate cancer (PCa) on magnetic resonance imaging (MRI) remains challenging using clinical subjective assessment due to overlap between PCa and benign prostatic hyperplasia (BPH). The objective of this paper is to describe a deep-learning-based framework for fully automated detection of PCa in the TZ using T2-weighted (T2W) and apparent diffusion coefficient (ADC) map MR images. METHOD: This was a single-center IRB-approved cross-sectional study of men undergoing 3T MRI on two systems. The dataset consisted of 196 patients (103 with and 93 without clinically significant [Grade Group 2 or higher] TZ PCa) to train and test our proposed methodology, with an additional 168 patients with peripheral zone PCa used only for training. We proposed an ensemble of classifiers in which multiple U-Net-based models are designed for prediction of TZ PCa location on ADC map MR images, with initial automated segmentation of the prostate to guide detection. We compared accuracy of ADC alone to T2W and combined ADC+T2W MRI for input images, and investigated improvements using ensembles over their constituent models with different methods of diversity in individual models by hyperparameter configuration, loss function and model architecture. RESULTS: Our developed algorithm reported sensitivity and precision of 0.829 and 0.617 in 56 test cases containing 31 instances of TZ PCa and in 25 patients without clinically significant TZ tumors. Patient-wise classification accuracy had an area under receiver operator characteristic curve (AUROC) of 0.974. Single U-Net models using ADC alone (sensitivity 0.829, precision 0.534) outperformed assessment using T2W (sensitivity 0.086, precision 0.081) and assessment using combined ADC+T2W (sensitivity 0.687, precision 0.489). While the ensemble of U-Nets with varying hyperparameters demonstrated the highest performance, all ensembles improved PCa detection compared to individual models, with sensitivities and precisions close to the collective best of constituent models. CONCLUSION: We describe a deep-learning-based method for fully automated TZ PCa detection using ADC map MR images that outperformed assessment by T2W and ADC+T2W.