Efficacy and Safety of Radiation Segmentectomy with 90Y Resin Microspheres for Hepatocellular Carcinoma.

Background Limited data are available on radiation segmentectomy (RS) for treatment of hepatocellular carcinoma (HCC) using yttrium 90 (90Y) resin microsphere doses determined by using a single-compartment medical internal radiation dosimetry (MIRD) model. Purpose To evaluate the efficacy and safety of RS treatment of HCC with 90Y resin microspheres using a single-compartment MIRD model and correlate posttreatment dose with outcomes. Materials and Methods This retrospective single-center study included adult patients with HCC who underwent RS with 90Y resin microspheres between July 2014 and December 2022. Posttreatment PET/CT and dosimetry were performed. Adverse events were assessed using the Common Terminology Criteria for Adverse Events, version 5.0. Per-lesion and overall response rates (ie, complete response [CR], objective response, disease control, and duration of response) were assessed at imaging using the Modified Response Evaluation Criteria in Solid Tumors, and overall survival (OS) was assessed using Kaplan-Meier analysis. Results Among 67 patients (median age, 69 years [IQR, 63-78 years]; 54 male patients) with HCC, median tumor absorbed dose was 232 Gy (IQR, 163-405 Gy). At 3 months, per-lesion and overall (per-patient) CR was achieved in 47 (70%) and 41 (61%) of 67 patients, respectively. At 6 months (n = 46), per-lesion rates of objective response and disease control were both 94%, and per-patient rates were both 78%. A total of 88% (95% CI: 79 99) and 72% (95% CI: 58, 90) of patients had a per-lesion and overall duration of response of 1 year or greater. At 1 month, a grade 3 clinical adverse event (abdominal pain) occurred in one of 67 (1.5%) patients. Median posttreatment OS was 26 months (95% CI: 20, not reached). Disease progression at 2 years was lower in the group that received 300 Gy or more than in the group that received less than 300 Gy (17% vs 61%; P = .047), with no local progression in the former group through the end of follow-up. Conclusion Among patients with HCC who underwent RS with 90Y resin microspheres, 88% and 72% achieved a per-lesion and overall duration of response of 1 year or greater, respectively, with one grade 3 adverse event. In patients whose tumors received 300 Gy or more according to posttreatment dosimetry, a disease progression benefit was noted. © RSNA, 2024 Supplemental material is available for this article.

Percutaneous CT-Guided Cryoablation for Locally Recurrent Prostate Cancer: Technical Feasibility, Safety, and Effectiveness.

PURPOSE: To assess the feasibility and safety of using computed tomography (CT) guidance for ablation of prostate cancer in the salvage setting. MATERIALS AND METHODS: This institutional review board-approved retrospective study of consecutive patients who presented with prostate cancer recurrence and underwent percutaneous CT-guided cryoablation was conducted between July 2020 and September 2022. A total of 18 patients met the inclusion criteria, and a total of 19 procedures were performed. Demographic details; preablation and postablation urinary, rectal, and erectile function assessment; procedure details; and preoperative and postoperative imaging findings and prostate-specific antigen (PSA) values were recorded. RESULTS: The mean treated tumor size was 15.7 mm ± 6.2. Technical success was achieved in 18 of the 19 procedures (94.7%), with 1 procedure aborted due to inability to obtain a safe plane. The mean follow-up time was 10.0 months (range, 2.3-26.7 months) at the time of manuscript preparation. The mean PSA before ablation was 8.1 ng/mL ± 9.3, and postablation PSA nadir was 2.6 ng/mL ± 4.0 (P = .002). Of the 18 patients who had postoperative imaging, 16 (88.9%) had a complete response (ie, no evidence of residual disease), and 2 (11.1%) patients had residual disease. Overall, 16 (88.9%) of the 18 treated patients demonstrated a PSA and/or imaging response to ablation. Mild adverse events occurred in 4 (22%) of the 18 cases. CONCLUSIONS: CT-guided cryoablation appears to be a technically feasible, safe option for treating locally recurrent prostate cancer.

MRI of Lymphedema.

Lymphedema is a devastating disease that has no cure. Management of lymphedema has evolved rapidly over the past two decades with the advent of surgeries that can ameliorate symptoms. MRI has played an increasingly important role in the diagnosis and evaluation of lymphedema, as it provides high spatial resolution of the distribution and severity of soft tissue edema, characterizes diseased lymphatic channels, and assesses secondary effects such as fat hypertrophy. Many different MR techniques have been developed for the evaluation of lymphedema, and the modality can be tailored to suit the needs of a lymphatic clinic. In this review article we provide an overview of lymphedema, current management options, and the current role of MRI in lymphedema diagnosis and management. EVIDENCE LEVEL: 5 TECHNICAL EFFICACY: Stage 5.

Unexplained Acute Distal Pancreatitis: Association With Subsequent Diagnosis of Pancreatic Cancer.

BACKGROUND. Distal pancreatitis is an atypical imaging subtype of acute pancreatitis involving only the pancreatic body and tail, the head being spared. If no cause is identified, suspicion of a small imaging-occult cancer may be warranted. OBJECTIVE. The purpose of this study was to determine the frequency of subsequently diagnosed pancreatic cancer in patients with unexplained acute distal pancreatitis and to compare this frequency to that found in patients with unexplained nondistal pancreatitis. METHODS. This retrospective study included patients who underwent contrast-enhanced CT between January 1, 2019, and December 31, 2020, that showed acute pancreatitis without identifiable explanation. Studies were classified as showing distal or nondistal acute pancreatitis on the basis of consensus. The Fisher exact test was used to compare the frequency of subsequent histologic diagnosis of pancreatic cancer between groups. Negative classification required 6 or more months of imaging follow-up and/or 12 or more months of clinical follow-up. Interreader agreement among seven readers of varying experience was assessed by Fleiss kappa. RESULTS. Among 215 patients with acute pancreatitis, 116 (54%) had no identifiable explanation and formed the study sample. A total of 100 of 116 (86%) patients (59 men, 41 women; mean age, 57 ± 18 [SD] years) had nondistal acute pancreatitis; 16 of 116 (14%) patients (10 men, six women; mean age, 66 ± 14 years) had distal acute pancreatitis. Among patients with nondistal pancreatitis, none were subsequently diagnosed with pancreatic cancer; 62 had sufficient follow-up (median, 2.5 years) to be classified as having negative follow-up for pancreatic cancer. Among patients with distal pancreatitis, nine were subsequently diagnosed with pancreatic cancer (median interval to suspected cancer on subsequent CT, 174 days); five had sufficient follow-up (median, 3.1 years) to be classified as having negative follow-up for pancreatic cancer. The frequency of pancreatic cancer was higher (p < .001) in patients with distal pancreatitis (9/14 [64%; 95% CI, 35-87%]) than in with those with nondistal pancreatitis (0/62 [0%; 95% CI, 0-6%]). Interreader agreement on classification of distal versus nondistal pancreatitis was almost perfect (κ = 0.81). CONCLUSION. Distal pancreatitis without identifiable cause on CT is an uncommon but unique imaging subtype of acute pancreatitis that is associated with a high frequency of pancreatic cancer. CLINICAL IMPACT. In patients with acute distal pancreatitis without identifiable cause, endoscopic ultrasound-guided biopsy should be considered to evaluate for an underlying small cancer.

Fluid Distribution Patterns in Early-Stage Upper Extremity Lymphedema.

INTRODUCTION: Magnetic resonance imaging (MRI) stage 1 (early stage) upper extremity lymphedema is characterized by fluid infiltration in the subcutaneous tissues that does not exceed 50% of the extremity circumference at any level. The spatial fluid distribution in these cases has not been detailed and may be important to help determine the presence and location of compensatory lymphatic channels. The aim of this study is to determine whether there was a pattern of distribution of fluid infiltration in patients with early-stage lymphedema that could correspond to known lymphatic pathways in the upper extremity. METHODS: A retrospective review identified all patients with MRI stage 1 upper extremity lymphedema who were evaluated at a single lymphatic center. Using a standardized scoring system, a radiologist graded the severity of fluid infiltration at 18 anatomical locations. A cumulative spatial histogram was then created to map out regions where fluid accumulation occurred most and least frequently. RESULTS: Eleven patients with MRI stage 1 upper extremity lymphedema were identified between January 2017 and January 2022. The mean age was 58 years and the mean BMI was 30 m/kg2. One patient had primary lymphedema and the remaining 10 had secondary lymphedema. The forearm was affected in nine cases, and fluid infiltration was predominantly concentrated along the ulnar aspect, followed by the volar aspect, while the radial aspect was completely spared. Within the upper arm, fluid was primarily concentrated distally and posteriorly, and occasionally medially. CONCLUSIONS: In patients with early-stage lymphedema, fluid infiltration is concentrated along the ulnar forearm and the posterior distal upper arm, which aligns with the tricipital lymphatic pathway. There is also sparing of fluid accumulation along the radial forearm in these patients, suggesting a more robust lymphatic drainage along this region, possibly due to a connection to the lateral upper arm pathway.

Omental vascularized lymph node transplant for the treatment of breast lymphedema: A case report.

Breast lymphedema is a type of breast cancer related lymphedema that leads to significant discomfort and negative impact on body image. Conservative therapy and lymphovenous bypass have been previously described as possible treatment methods for breast lymphedema, however, a unified approach to treatment is lacking. The current report describes a case of breast lymphedema successfully treated with vascularized lymph node transfer (VLNT) after failed attempt at management with conservative therapy. The patient is a 48-year-old female with right-sided breast cancer who underwent breast conservation therapy in 2015 and subsequently developed pain and swelling of the right breast. The diagnosis of breast lymphedema was supported by clinical evaluation as well as MRI, lymphoscintigraphy, and lymphography. In consultation with a breast surgeon, breast lymphedema was determined not to be an indication for mastectomy. The patient was offered and underwent an omental VLNT to the right breast. A 20 cm segment of omentum with associated gastroepiploic vessels and lymph nodes was harvested, transferred to the right axilla and gastroepiploic vessels were anastomosed to the recipient thoracodorsal vessels. The patient tolerated the procedure well and there were no complications. Additional donor sites were considered, such as the groin and submental regions, but an omental flap was favored in this case because of the lower risk of donor site lymphedema. In the years following, the patient reported significant improvement in symptoms as well as objective reduction of edema on MRI. We propose the consideration of VLNT for breast lymphedema refractory to other methods of management.

Edematous Dermal Thickening on Magnetic Resonance Imaging as a Biomarker for Lymphatic Surgical Outcomes.

Background and Objectives: One of the surgical treatments for breast cancer-related lymphedema (BCRL) is debulking lipectomy. The aim of this study is to investigate whether dermal thickness could be utilized as an objective indicator of post-operative changes following debulking. Materials and Methods: A retrospective review of BCRL patients who underwent debulking lipectomy was conducted. MRI-based dermal thickness was measured by two separate trained readers at 16 regions of the upper extremity. Pre- and post-operative reduction in dermal thickness was compared across the affected and unaffected (control) arms for each patient. The Wilcoxon rank sum test was used to assess for significant change. Univariate linear regression was used to assess the relationship between dermal thickness reduction and changes to LYMPH-Q scores, L-Dex scores, and relative volume change. Results: Seventeen patients were included in our analysis. There was significant reduction in dermal thickness at 5/16 regions in the affected arm. Dermal thickness change was significantly correlated with LYMPH-Q scores, L-Dex scores, and relative volume change in 2/16 limb compartments. There was predominant dermal thickening in the dorsal compartment of the upper arm and in the ventral and ulnar compartments of the forearm. Conclusions: Dermal thickness shows promising utility in tracking post-operative debulking procedures for breast cancer-related lymphedema. Further studies with larger patient populations and a variety of imaging modalities are required to continue to develop a clinically objective and reproducible method of post-surgical lymphedema staging and monitoring.

Real-time diagnosis and Gleason grading of prostate core needle biopsies using nonlinear microscopy.

Rapid histologic assessment of fresh prostate biopsies may reduce patient anxiety, aid in biopsy sampling, and enable specimen triaging for molecular/genomic analyses and research that could benefit from fresh tissue analysis. Nonlinear microscopy (NLM) is a fluorescence microscopy technique that can produce high-resolution images of freshly excised tissue resembling formalin-fixed paraffin-embedded (FFPE) H&E. NLM enables evaluation of tissue up to ~100 µm below the surface, analogous to serial sectioning, but without requiring microtome sectioning. One hundred and seventy biopsies were collected from 63 patients who underwent in-bore MRI or MRI/ultrasound fusion biopsy procedures. Biopsies were stained in acridine orange and sulforhodamine 101, a nuclear and cytoplasmic/stromal fluorescent dye, for 45 s. Genitourinary pathologists evaluated the biopsies using NLM by translating the biopsies in real time to areas of interest and NLM images were recorded. After NLM evaluation, the biopsies were processed for standard FFPE H&E and similarities and differences between NLM and FFPE H&E were investigated. Accuracies of NLM diagnoses and Gleason scores were calculated using FFPE histology as the gold standard. Pathologists achieved a 92.4% sensitivity (85.0-96.9%, 95% confidence intervals) and 100.0% specificity (94.3-100.0%) for detecting carcinoma compared to FFPE histology. The agreement between the Grade Group determined by NLM versus FFPE histology had an unweighted Cohen's Kappa of 0.588. The average NLM evaluation time was 2.10 min per biopsy (3.08 min for the first 20 patients, decreasing to 1.54 min in subsequent patients). Further studies with larger patient populations, larger number of pathologists, and multiple institutions are warranted. NLM is a promising method for future rapid evaluation of prostate needle core biopsies.

Zonal Growth Pattern of the Prostate Is Affected by Age and Body Mass Index.

PURPOSE: As men age, the prostate continues to grow on average 2.5% per year. While the variable growth rate of the total prostate gland is recognized, the growth rate of different prostate zones remains largely unclear. We evaluated the growth patterns of the prostate zones and identified clinical parameters contributing to the zonal growth rates. MATERIALS AND METHODS: Prostate magnetic resonance imaging (MRI) data and clinical information were obtained retrospectively on 156 patients who had at least 3 prostate MRIs between 2003 and 2018. Different prostate zonal volumes were measured and analyzed. The outcome was analyzed using linear regression. RESULTS: We observed that prostate growth rates vary depending on body mass index (BMI), transition zone index (TZI), the prostate zone and 5-alpha reductase inhibitor (5ARI) use. The peripheral zone volume growth rates increased with age and peaked at 60-70 years of age (p=0.047), while the transition zone volume demonstrates continuous growth without a peak through all ages. BMI and TZI are associated with the growth rate of the peripheral zone (p=0.026, p <0.001, respectively) but not the transition zone growth rate. 5ARI use is significantly associated with the reduction in the transition zone growth rate (p=0.033), not the peripheral zone. In addition, patients with TZI greater than 60% had the most significant reduction in the transition zone growth rate while taking 5ARI (p <0.001). CONCLUSIONS: Transition and peripheral zones of the prostate grow at variable rates. BMI and TZI affect peripheral zone growth rate, while 5ARI use reduces the transition zone growth rate.

Spectrum of MRI Features of Mucin-producing Neoplasms in the Abdomen and Pelvis.

Mucin-producing neoplasms in the abdomen and pelvis are a distinct entity, separate from simple fluid-containing neoplasms and loculated fluid collections. Mucin is a thick gelatinous substance and-owing to its high water content-has imaging features that can be mistaken for those of simple fluid-containing neoplasms with multiple imaging modalities. However, mucin-producing neoplasms arise from specific organs in the abdomen and pelvis, with unique imaging appearances, knowledge of which is important to guide accurate diagnosis and management. With its large field of view and high soft-tissue resolution, MRI has advantages over other imaging modalities in characterizing these neoplasms. The authors focus on the spectrum of MRI features of such mucin-producing neoplasms and illustrate how-despite a varied organ origin-some of these neoplasms share similar MRI and histopathologic features, thereby helping narrow the differential diagnosis. One common finding in these tumors is that the presence of internal complexity and solid enhancing components increases as the degree of malignant transformation increases. Lack of internal complexity generally indicates benignity. These tumors have a varied range of prognosis; for example, a low-grade appendiceal mucinous neoplasm is indicative of a good prognosis, while a mucinous tumor of the rectum is known to manifest at an early age with aggressive behavior and poorer prognosis compared with its nonmucinous counterpart. Online supplemental material is available for this article. ©RSNA, 2022.

Arterial Spin Labeled Perfusion MRI for the Evaluation of Response to Tyrosine Kinase Inhibition Therapy in Metastatic Renal Cell Carcinoma.

Background Tumor perfusion may inform therapeutic response and resistance in metastatic renal cell carcinoma (RCC) treated with antiangiogenic therapy. Purpose To determine if arterial spin labeled (ASL) MRI perfusion changes are associated with tumor response and disease progression in metastatic RCC treated with vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitors (TKIs). Materials and Methods In this prospective study (ClinicalTrials.gov identifier: NCT00749320), metastatic RCC perfusion was measured with ASL MRI before and during sunitinib or pazopanib therapy between October 2008 and March 2014. Objective response rate (ORR) and progression-free survival (PFS) were calculated. Perfusion was compared between responders and nonresponders at baseline, at week 2, after cycle 2 (12 weeks), after cycle 4 (24 weeks), and at disease progression and compared with the ORR by using the Wilcoxon rank sum test and with PFS by using the log-rank test. Results Seventeen participants received sunitinib (mean age, 59 years ± 7.0 [standard deviation]; 11 men); 11 participants received pazopanib (mean age, 63 years ± 6.6; eight men). Responders had higher baseline tumor perfusion than nonresponders (mean, 404 mL/100 g/min ± 213 vs 199 mL/100 g/min ± 136; P = .02). Perfusion decreased from baseline to week 2 (-53 mL/100 g/min ± 31; P < .001), after cycle 2 (-65 mL/100 g/min ± 25; P < .001), and after cycle 4 (-79 mL/100 g/min ± 15; P = .008). Interval reduction in perfusion at those three time points was not associated with ORR (P = .63, .29, and .27, respectively) or PFS (P = .28, .27, and .32). Perfusion increased from cycle 4 to disease progression (51% ± 11; P < .001). Conclusion Arterial spin labeled perfusion MRI may assist in identifying responders to vascular endothelial growth factor receptor tyrosine kinase inhibitors and may help detect early evidence of disease progression in patients with metastatic renal cell carcinoma. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Goh and De Vita in this issue.

Breast Cancer-Related Lymphedema: Magnetic Resonance Imaging Evidence of Sparing Centered Along the Cephalic Vein.

BACKGROUND: A distinct pattern of edema distribution is seen in breast cancer-related lymphedema. The area of edema sparing has not been characterized in relation to anatomy. Specifically, alternate lymphatic pathways are known to travel adjacent to the cephalic vein. Our study aims to define the location of edema sparing in the arm relative to the cephalic vein. METHODS: A retrospective review of patients who underwent magnetic resonance imaging (MRI) between March 2017 and September 2018 was performed. Variables including patient demographics, arm volumes, and MRI data were extracted. MRIs were reviewed to define the amount of sparing, or angle of sparing, and the deviation between the center of sparing and the cephalic vein, or angle of deviation. RESULTS: A total of 34 consecutive patients were included in the analysis. Five patients demonstrated circumferential edema (no sparing) and 29 patients demonstrated areas of edema sparing. Advanced age (69.7 vs. 57.6 years) and greater excess arm volume (40.4 vs. 20.8%) correlated with having circumferential edema without sparing (p = 0.003). In 29 patients with areas of edema sparing, the upper arm demonstrated the greatest angle of sparing (183.2 degrees) and the narrowest in the forearm (99.9 degrees; p = 0.0032). The mean angle of deviation to the cephalic vein measured 3.2, -0.1, and -5.2 degrees at the upper arm, elbow, and forearm, respectively. CONCLUSION: Our study found that the area of edema sparing, when present, is centered around the cephalic vein. This may be explained by the presence of the Mascagni-Sappey (M-S) pathway as it is located alongside the cephalic vein. Our findings represent a key springboard for additional research to better elucidate any trends between the presence of the M-S pathway, areas of sparing, and severity of lymphedema.

Pancreatic perfusion modulation following glucose stimulation assessed by noninvasive arterial spin labeling (ASL) MRI.

BACKGROUND: More than 100 million adults in the US suffer from prediabetes or type-2 diabetes. Noninvasive imaging of pancreas endocrine function might provide a surrogate marker of ß-cell functional integrity loss linked to this disease. PURPOSE: To noninvasively assess pancreatic blood-flow modulation following a glucose challenge using arterial spin labeling (ASL) MRI. STUDY TYPE: Prospective. SUBJECTS: Fourteen adults (30 ± 7 years old, 3M/11F, body mass index [BMI] = 24 ± 3 kg.m-2 ). FIELD STRENGTH/SEQUENCE: 3T MRI / background-suppressed pseudocontinuous PCASL preparation with single-shot fast-spin-echo (FSE) readout before and after an oral glucose challenge using either fruit juice (n = 7) or over-the-counter glucose gel (n = 7). ASSESSMENT: Subjects were fasting prior to initiation of oral stimulation, then dynamic perfusion measurements were performed every 2 minutes for 30 minutes. We quantified absolute blood flow at each timepoint. STATISTICAL TESTS: Repeated-measures analysis of variance (ANOVA) followed by paired t-tests to assess for a significant effect of glucose challenge on measured perfusion. RESULTS: Measured basal blood flow was 187 ± 53 mL/100g/min. A significant blood flow increase of +38 ± 26% was observed 10 minutes poststimulation (P < 0.05) and continuing until the end of the experiment. The gel stimulation provided the most consistent results, with an early rise followed by an additional later increase consistent with the known pancreatic insulin response to elevated blood glucose. Across-subject variations in blood flow increase were partially attributable to basal flow, with a negative correlation of r = -0.84 between basal and maximal relative flow increase in the gel group. DATA CONCLUSION: ASL can be used to measure pancreatic flow in response to a glucose challenge, which could be linked to insulin release and secretion. This paradigm might be useful to characterize disorders of glucose regulation. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2020;51:854-860.

MRI staging of upper extremity secondary lymphedema: correlation with clinical measurements.

OBJECTIVES: Staging of upper extremity lymphedema is needed to guide surgical management, but is not standardized due to lack of accessible, quantitative, or precise measures. Here, we established an MRI-based staging system for lymphedema and validate it against existing clinical measures. METHODS: Bilateral upper extremity MRI and lymphoscintigraphy were performed on 45 patients with unilateral secondary lymphedema, due to surgical intervention, who were referred to our multidisciplinary lymphedema clinic between March 2017 and October 2018. MRI short-tau inversion recovery (STIR) images were retrospectively reviewed. A grading system was established based on the cross-sectional circumferential extent of subcutaneous fluid infiltration at three locations, labeled MRI stage 0-3, and was compared to L-Dex®, ICG lymphography, volume, lymphedema quality of life (LYMQOL), International Society of Lymphology (ISL) stage, and lymphoscintigraphy. Linear weighted Cohen's kappa was calculated to compare MRI staging by two readers. RESULTS: STIR images on MRI revealed a predictable pattern of fluid infiltration centered on the elbow and extending along the posterior aspect of the upper arm and the ulnar side of the forearm. Patients with higher MRI stage were more likely to be in ISL stage 2 (p = 0.002) or to demonstrate dermal backflow on lymphoscintigraphy (p = 0.0002). No correlation was found between MRI stages and LYMQOL. Higher MRI stage correlated with abnormal ICG lymphography pattern (rs = 0.63, p < 0.0001), larger % difference in limb volume (rs = 0.68, p < 0.0001), and higher L-Dex® ratio (rs = 0.84, p < 0.0001). Cohen's kappa was 0.92 (95% CI, 0.85-1.00). CONCLUSION: An MRI staging system for upper extremity lymphedema offers an improved non-invasive precision marker for lymphedema for therapeutic planning. KEY POINTS: • Diagnosis and staging of patients with secondary upper extremity lymphedema may be performed with non-contrast MRI, which is non-invasive and more readily accessible compared to lymphoscintigraphy and evaluation by lymphedema specialists. • MRI-based staging of secondary upper extremity lymphedema is highly reproducible and could be used for long-term follow-up of patients. • In patients with borderline clinical measurements, MRI can be used to identify patients with early-stage lymphedema.

A Practical Guide to MR Imaging Safety: What Radiologists Need to Know.

Magnetic resonance (MR) imaging can provide critical diagnostic and anatomic information while avoiding the use of ionizing radiation, but it has a unique set of safety risks associated with its reliance on large static and changing magnetic fields, high-powered radiofrequency coil systems, and exogenous contrast agents. It is crucial for radiologists to understand these risks and how to mitigate them to protect themselves, their colleagues, and their patients from avoidable harm and to comply with safety regulations at MR imaging sites. Basic knowledge of MR imaging physics and hardware is necessary for radiologists to understand the origin of safety regulations and to avoid common misconceptions that could compromise safety. Each of the components of the MR imaging unit can be a factor in injuries to patients and personnel. Safety risks include translational force and torque, projectile injury, excessive specific absorption rate, burns, peripheral neurostimulation, interactions with active implants and devices, and acoustic injury. Standards for MR imaging device safety terminology were first issued in 2005 and are required by the U.S. Food and Drug Administration, with devices labeled as "MR safe," "MR unsafe," or "MR conditional." MR imaging contrast agent safety is also discussed. Additional technical and safety policies relate to pediatric, unconscious, incapacitated, or pregnant patients and pregnant imaging personnel. Division of the MR imaging environment into four distinct, clearly labeled zones--with progressive restriction of entry and increased supervision for higher zones--is a mandatory and key aspect in avoidance of MR imaging-related accidents. All MR imaging facilities should have a documented plan to handle emergencies within zone IV, including cardiac arrest or code, magnet quench, and fires. Policies from the authors' own practice are provided for additional reference. Online supplemental material is available for this article.

Evaluation of Primary Lymphedema with Intranodal Lymphangiography.

PURPOSE: There are limited existing data on the lymphatic anatomy of patients with primary lymphedema (LED), which is caused by aberrant development of lymphatic channels. In addition, there is a paucity of contemporary studies that use groin intranodal lymphangiography (IL) to evaluate LED anatomy. The purpose of this retrospective observational study was to better delineate the disease process and anatomy of primary LED using groin IL. MATERIALS AND METHODS: We identified common groin IL findings in a cohort of 17 primary LED patients performed between 1/1/2017 and 1/31/2022 at a single institution. These patients were clinically determined to have primary lymphedema and demonstrated associated findings on lower extremity MR and lymphoscintigraphy. RESULTS: Ten patients (59%) demonstrated irregular lymph node morphology or a paucity of lymph nodes on the more symptomatic laterality. Eight patients (47%) demonstrated lymphovenous shunting from pre-existing anastomoses between the lymphatic and venous systems. Eight patients (47%) demonstrated passage of contrast past midline to the contralateral lymphatics. Finally, 12 patients (71%) failed to opacify the cisterna chyli and thoracic duct on their initial lymphangiograms. Delayed computed tomography of 3 patients showed eventual central lymphatic opacification up to the renal veins, but none of these patients showed central lymphatic opacification to the thorax. CONCLUSION: This descriptive, exploratory study demonstrates common central groin IL findings in primary LED to highlight patterns interventional radiologists should identify and report when addressing primary LED.

A case report of a prostate cancer metastasis in the pancreas exhibiting vascular encasement.

We report a patient who presented with a 4-month history of intermittent epigastric pain. Computed tomography (CT) angiography of the abdomen demonstrated a stenotic celiac trunk but also encasement of the common proper hepatic artery, gastroduodenal artery, and proper hepatic artery by an ill-defined hypoattenuating mass of the pancreatic head. Biopsy confirmed metastatic prostate cancer to the pancreas that occurred 4 years after radiation and androgen deprivation therapy. A follow-up staging study demonstrated an osseous metastasis at the T4 spinous process. This case demonstrates an unusual case of prostate metastasis to the pancreas with the involvement of a main abdominal vessel. With treatment improvements leading to longer survival rates from prostate cancer, radiologists should be aware of atypical metastases that may arise in the long term.

Characterizing Metabolic Heterogeneity of Hepatocellular Carcinoma with Hyperpolarized 13C Pyruvate MRI and Mass Spectrometry.

Purpose To characterize the metabolomic profiles of two hepatocellular carcinoma (HCC) rat models, track evolution of these profiles to a stimulated tumor state, and assess their effect on lactate flux with hyperpolarized (HP) carbon 13 (13C) MRI. Materials and Methods Forty-three female adult Fischer rats were implanted with N1S1 or McA-RH7777 HCC tumors. In vivo lactate-to-pyruvate ratio (LPR) was measured with HP 13C MRI at 9.4 T. Ex vivo mass spectrometry was used to measure intratumoral metabolites, and Ki67 labeling was used to quantify proliferation. Tumors were first compared with three normal liver controls. The tumors were then compared with stimulated variants via off-target hepatic thermal ablation treatment. All comparisons were made using the Mann-Whitney test. Results HP 13C pyruvate MRI showed greater LPR in N1S1 tumors compared with normal liver (mean [SD], 0.564 ± 0.194 vs 0.311 ± 0.057; P < .001 [n = 9]), but not for McA-RH7777 (P = .44 [n = 8]). Mass spectrometry confirmed that the glycolysis pathway was increased in N1S1 tumors and decreased in McA-RH7777 tumors. The pentose phosphate pathway was also decreased only in McA-RH7777 tumors. Increased proliferation in stimulated N1S1 tumors corresponded to a net increase in LPR (six stimulated vs six nonstimulated, 0.269 ± 0.148 vs 0.027 ± 0.08; P = .009), but not in McA-RH7777 (eight stimulated vs six nonstimulated, P = .13), despite increased proliferation and metastases. Mass spectrometry demonstrated relatively increased lactate production with stimulation in N1S1 tumors only. Conclusion Two HCC subtypes showed divergent glycolytic dependency at baseline and during transformation to a high proliferation state. This metabolic heterogeneity in HCC should be considered with use of HP 13C MRI for diagnosis and tracking. Keywords: Molecular Imaging-Probe Development, Liver, Abdomen/GI, Oncology, Hepatocellular Carcinoma © RSNA, 2024 See also commentary by Ohliger in this issue.

How Can We Identify Extraprostatic Extension (EPE) Before Surgery? The Use of a Preoperative Prostate MRI EPE Scoring System to Assess Postprostatectomy Locally Advanced Prostate Cancer.

Background: Distinguishing between organ-confined disease and extraprostatic extension (EPE) is crucial for the treatment of patients with prostate cancer. EPE is associated with an increased risk of biochemical recurrence, positive surgical margins, and metastatic disease. An MRI-based EPE scoring system was developed by Mehralivand in 2019; however, it has not been adopted in the Urology community. The purpose of this study is to evaluate the association of MRI-based EPE scoring with the pathologic EPE (pEPE) after radical prostatectomy. Methods: We conducted a retrospective review on a prospectively collected database of male patients who underwent a prostate MRI with EPE scoring by a trained genitourinary radiologist and subsequent robotic radical prostatectomy at our institution from September 2020 to December 2022. The associations between MRI EPE (mEPE) score and the presence of EPE on surgical pathology (pEPE) were examined using multivariable logistic regression. Results: A total of 194 patients met inclusion criteria with a median age of 63 years and prostate specific antigen (PSA) 7 ng/mL. Among those with mEPE score 3, 96% had pEPE. Those patients with an mEPE score ≥2 had an increased risk of pEPE compared with those with mEPE score 0 (odds ratio 3.79; 95% confidence interval 1.28-11.3) Furthermore, those with an mEPE score 3 were significantly more likely to have pEPE compared with those with mEPE score 0, 1 and 2 independently. Conclusion: MRI EPE is a straightforward tool that strongly correlates with the presence of pEPE. If validated prospectively, this scoring system could assist in counseling patients regarding nerve-sparing approach.