Prototype Description and Ex Vivo Evaluation of a System for Combined Endorectal Magnetic Resonance Imaging and In-Bore Biopsy of the Prostate.

ABSTRACT: We describe early ex vivo proof-of-concept testing of a novel system composed of a disposable endorectal coil and converging multichannel needle guide with a reusable clamp stand, embedded electronics, and baseplate to allow for endorectal magnetic resonance (MR) imaging and in-bore MRI-targeted biopsy of the prostate as a single integrated procedure. Using prostate phantoms imaged with standard T 2 -weighted sequences in a Siemens 3T Prisma MR scanner, we measured the signal-to-noise ratio in successive 1-cm distances from the novel coil and from a commercially available inflatable balloon coil and measured the lateral and longitudinal deviation of the tip of a deployed MR compatible needle from the intended target point. Signal-to-noise ratio obtained with the novel system was significantly better than the inflatable balloon coil at each of five 1-cm intervals, with a mean improvement of 78% ( P < 0.05). In a representative sampling of 15 guidance channels, the mean lateral deviation for MR imaging-guided needle positioning was 1.7 mm and the mean longitudinal deviation was 2.0 mm. Our ex vivo results suggest that our novel system provides significantly improved signal-to-noise ratio when compared with an inflatable balloon coil and is capable of accurate MRI-guided needle deployment.

Metabolic activity diffusion imaging (MADI): II. Noninvasive, high-resolution human brain mapping of sodium pump flux and cell metrics.

We introduce a new 1 H2 O magnetic resonance approach: metabolic activity diffusion imaging (MADI). Numerical diffusion-weighted imaging decay simulations characterized by the mean cellular water efflux (unidirectional) rate constant (kio ), mean cell volume (V), and cell number density (ρ) are produced from Monte Carlo random walks in virtual stochastically sized/shaped cell ensembles. Because of active steady-state trans-membrane water cycling (AWC), kio reflects the cytolemmal Na+ , K+ ATPase (NKA) homeostatic cellular metabolic rate (c MRNKA ). A digital 3D "library" contains thousands of simulated single diffusion-encoded (SDE) decays. Library entries match well with disparate, animal, and human experimental SDE decays. The V and ρ values are consistent with estimates from pertinent in vitro cytometric and ex vivo histopathological literature: in vivo V and ρ values were previously unavailable. The library allows noniterative pixel-by-pixel experimental SDE decay library matchings that can be used to advantage. They yield proof-of-concept MADI parametric mappings of the awake, resting human brain. These reflect the tissue morphology seen in conventional MRI. While V is larger in gray matter (GM) than in white matter (WM), the reverse is true for ρ. Many brain structures have kio values too large for current, invasive methods. For example, the median WM kio is 22s-1 ; likely reflecting mostly exchange within myelin. The kio •V product map displays brain tissue c MRNKA variation. The GM activity correlates, quantitatively and qualitatively, with the analogous resting-state brain 18 FDG-PET tissue glucose consumption rate (t MRglucose ) map; but noninvasively, with higher spatial resolution, and no pharmacokinetic requirement. The cortex, thalamus, putamen, and caudate exhibit elevated metabolic activity. MADI accuracy and precision are assessed. The results are contextualized with literature overall homeostatic brain glucose consumption and ATP production/consumption measures. The MADI/PET results suggest different GM and WM metabolic pathways. Preliminary human prostate results are also presented.

In-Bore Versus Fusion MRI-Targeted Biopsy of PI-RADS Category 4 and 5 Lesions: A Retrospective Comparative Analysis Using Propensity Score Weighting.

BACKGROUND. Few published studies have compared in-bore and fusion MRI-targeted prostate biopsy, and the available studies have had conflicting results. OBJECTIVE. The purpose of this study was to compare the target-specific cancer detection rate of in-bore prostate biopsy with that of fusion MRI-targeted biopsy. METHODS. The records of men who underwent in-bore or fusion MRI-targeted biopsy of PI-RADS category 4 or 5 lesions between August 2013 and September 2019 were retrospectively identified. PI-RADS version 2.1 assessment category, size, and location of each target were established by retrospective review by a single experienced radiologist. Patient history and target biopsy results were obtained by electronic medical record review. Only the first MRI-targeted biopsy of the dominant lesion was included for patients with repeated biopsies or multiple targets. In-bore and fusion biopsy were compared by propensity score weights and multivariable regression to adjust for imbalances in patient and target characteristics between biopsy techniques. The primary endpoint was target-specific prostate cancer detection rate. Secondary endpoints were detection rate after application of propensity score weighting for cancers in International Society of Urological Pathology (ISUP) grade group 2 (GG2) or higher and detection rate with the use of off-target systematic sampling results. RESULTS. The study sample included 286 men (in-bore biopsy, 191; fusion biopsy, 95). Compared with fusion biopsy, in-bore biopsy was associated with significantly greater likelihood of detection of any cancer (odds ratio, 2.28 [95% CI, 1.04-4.98]; p = .04) and nonsignificantly greater likelihood of detection of ISUP GG2 or higher cancer (odds ratio, 1.57 [95% CI, 0.88-2.79]; p = .12) in a target. When off-target sampling was included, in-bore biopsy and combined fusion and systematic biopsy were not different for detection of any cancer (odds ratio, 1.16 [95% CI, 0.54-2.45]; p = .71) or ISUP GG2 and higher cancer (odds ratio, 1.15 [95% CI, 0.66-2.01]; p = .62). CONCLUSION. In this retrospective study in which propensity score weighting was used, in-bore MRI-targeted prostate biopsy had a higher target-specific cancer detection rate than did fusion biopsy. CLINICAL IMPACT. Pending a larger prospective randomized multicenter comparison between in-bore and fusion biopsy, in-bore may be the preferred approach should performing only biopsy of a suspicious target, without concurrent systematic biopsy, be considered clinically appropriate.

Variability of the Positive Predictive Value of PI-RADS for Prostate MRI across 26 Centers: Experience of the Society of Abdominal Radiology Prostate Cancer Disease-focused Panel.

Background Prostate MRI is used widely in clinical care for guiding tissue sampling, active surveillance, and staging. The Prostate Imaging Reporting and Data System (PI-RADS) helps provide a standardized probabilistic approach for identifying clinically significant prostate cancer. Despite widespread use, the variability in performance of prostate MRI across practices remains unknown. Purpose To estimate the positive predictive value (PPV) of PI-RADS for the detection of high-grade prostate cancer across imaging centers. Materials and Methods This retrospective cross-sectional study was compliant with the HIPAA. Twenty-six centers with members in the Society of Abdominal Radiology Prostate Cancer Disease-focused Panel submitted data from men with suspected or biopsy-proven untreated prostate cancer. MRI scans were obtained between January 2015 and April 2018. This was followed with targeted biopsy. Only men with at least one MRI lesion assigned a PI-RADS score of 2-5 were included. Outcome was prostate cancer with Gleason score (GS) greater than or equal to 3+4 (International Society of Urological Pathology grade group ≥2). A mixed-model logistic regression with institution and individuals as random effects was used to estimate overall PPVs. The variability of observed PPV of PI-RADS across imaging centers was described by using the median and interquartile range. Results The authors evaluated 3449 men (mean age, 65 years ± 8 [standard deviation]) with 5082 lesions. Biopsy results showed 1698 cancers with GS greater than or equal to 3+4 (International Society of Urological Pathology grade group ≥2) in 2082 men. Across all centers, the estimated PPV was 35% (95% confidence interval [CI]: 27%, 43%) for a PI-RADS score greater than or equal to 3 and 49% (95% CI: 40%, 58%) for a PI-RADS score greater than or equal to 4. The interquartile ranges of PPV at these same PI-RADS score thresholds were 27%-44% and 27%-48%, respectively. Conclusion The positive predictive value of the Prostate Imaging and Reporting Data System was low and varied widely across centers. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Milot in this issue.

Impact of Direct MRI-Guided Biopsy of the Prostate on Clinical Management.

OBJECTIVE. The purpose of this study is to investigate the impact of direct MRI-guided biopsy of the prostate on clinical management in practice. MATERIALS AND METHODS. We retrospectively identified 127 patients with unknown (n = 98) or untreated prostate cancer with a Gleason score of 6 (n = 29) who underwent direct MRI-guided biopsy of the prostate at our institution between August 2013 and January 2018, after initial multiparametric endorectal MRI examination revealed one or more Prostate Imaging Reporting and Data System (PI-RADS or PI-RADSv2) category 4 or 5 target lesion. All available medical and imaging records were reviewed to determine pertinent clinical details, biopsy findings, and postbiopsy management. RESULTS. The mean patient age was 68 years (interquartile range, 63-73 years). Findings from MRI-guided biopsy were positive for 93 of 127 patients (73%), with prostate cancer of Gleason score of 7 or higher diagnosed in 84 of these 93 patients (90%). When stratified by clinical scenario, the rate of positive biopsy findings was 66% (57/86) for patients who had negative findings from one or more prior transrectal ultrasound-guided biopsies, 83% (10/12) for biopsy-naive patients, and 90% (26/29) for patients undergoing active surveillance. Overall, 90 of 127 patients (71%) received a new (n = 67) or upgraded (n = 23) diagnosis of prostate cancer, and 57 of these 90 patients (63%) proceeded to receive treatment with prostatectomy, radiation, or androgen deprivation therapy. CONCLUSION. The results of this study suggest that direct MRI-guided biopsy is associated with high rates of significant prostate cancer detection and subsequent definitive treatment across common clinical scenarios and should be considered an important supplementary diagnostic tool in the appropriate setting.

Performance characteristics of magnetic resonance imaging without contrast agents or sedation in pediatric appendicitis.

BACKGROUND: Magnetic resonance imaging (MRI) has emerged as a promising modality for evaluating pediatric appendicitis. However optimal imaging protocols, including roles of contrast agents and sedation, have not been established and diagnostic criteria have not been fully evaluated. OBJECTIVE: To investigate performance characteristics of rapid MRI without contrast agents or sedation in the diagnosis of pediatric appendicitis. MATERIALS AND METHODS: We included patients ages 4-18 years with suspicion of appendicitis who underwent rapid MRI between October 2013 and March 2015 without contrast agent or sedation. After two-radiologist review, we determined performance characteristics of individual diagnostic criteria and aggregate diagnostic criteria by comparing MRI results to clinical outcomes. We used receiver operating characteristic (ROC) curves to determine cut-points for appendiceal diameter and wall thickness for optimization of predictive power, and we calculated area under the curve (AUC) as a measure of test accuracy. RESULTS: Ninety-eight MRI examinations were performed in 97 subjects. Overall, MRI had a 94% sensitivity, 95% specificity, 91% positive predictive value and 97% negative predictive value. Optimal cut-points for appendiceal diameter and wall thickness were ≥7 mm and ≥2 mm, respectively. Independently, those cut-points produced sensitivities of 91% and 84% and specificities of 84% and 43%. Presence of intraluminal fluid (30/33) or localized periappendiceal fluid (32/33) showed a significant association with acute appendicitis (P<0.01), with sensitivities of 91% and 97% and specificities of 60% and 50%. For examinations in which the appendix was not identified by one or both reviewers (23/98), the clinical outcome was negative. CONCLUSION: Rapid MRI without contrast agents or sedation is accurate for diagnosis of pediatric appendicitis when multiple diagnostic criteria are considered in aggregate. Individual diagnostic criteria including optimized cut-points of ≥7 mm for diameter and ≥2 mm for wall thickness demonstrate high sensitivities but relatively low specificities. Nonvisualization of the appendix favors a negative diagnosis.

Beyond Prostate Adenocarcinoma: Expanding the Differential Diagnosis in Prostate Pathologic Conditions.

Recent advances in magnetic resonance (MR) imaging of the prostate gland have dramatically improved the ability to detect and stage adenocarcinoma of the prostate, one of the most frequently diagnosed cancers in men and one of the most frequently diagnosed pathologic conditions of the prostate gland. A wide variety of nonadenocarcinoma diseases can also be seen with MR imaging, ranging from benign to malignant diseases, as well as infectious and inflammatory manifestations. Many of these diseases have distinctive imaging features that allow differentiation from prostate acinar adenocarcinoma. Early recognition of these entities produces a more accurate differential diagnosis and may enable more expeditious clinical workup. Benign neoplasms of the prostate include plexiform neurofibroma and cystadenoma, both of which demonstrate distinctive imaging features. Stromal neoplasms of uncertain malignant potential are rare tumors of uncertain malignant potential that are often difficult to distinguish at imaging from more-malignant prostate sarcomas. Other malignant neoplasms of the prostate include urothelial carcinoma, primary prostatic carcinoid, carcinosarcoma, endometrioid or ductal adenocarcinoma, and mucinous adenocarcinoma. Prostatic infections can lead to abscesses of pyogenic, tuberculous, or fungal origins. Finally, miscellaneous idiopathic disorders of the prostate include amyloidosis, exophytic benign prostatic hyperplasia, and various congenital cysts. Considerable overlap can exist in the clinical history and imaging findings associated with these prostate pathologic conditions, and biopsy is often required for ultimate confirmation of the diagnosis. However, many diagnoses, including cystadenoma, mucinous adenocarcinoma, sarcoma, and abscesses, have distinct imaging features, which can enable the informed radiologist to identify the diagnosis and recommend appropriate clinical workup and management. (©)RSNA, 2016.

Revised Atlanta Classification for Acute Pancreatitis: A Pictorial Essay.

The 2012 revised Atlanta classification is an update of the original 1992 Atlanta classification, a standardized clinical and radiologic nomenclature for acute pancreatitis and associated complications based on research advances made over the past 2 decades. Acute pancreatitis is now divided into two distinct subtypes, necrotizing pancreatitis and interstitial edematous pancreatitis (IEP), based on the presence or absence of necrosis, respectively. The revised classification system also updates confusing and sometimes inaccurate terminology that was previously used to describe pancreatic and peripancreatic collections. As such, use of the terms acute pseudocyst and pancreatic abscess is now discouraged. Instead, four distinct collection subtypes are identified on the basis of the presence of pancreatic necrosis and time elapsed since the onset of pancreatitis. Acute peripancreatic fluid collections (APFCs) and pseudocysts occur in IEP and contain fluid only. Acute necrotic collections (ANCs) and walled-off necrosis (WON) occur only in patients with necrotizing pancreatitis and contain variable amounts of fluid and necrotic debris. APFCs and ANCs occur within 4 weeks of disease onset. After this time, APFCs or ANCs may either resolve or persist, developing a mature wall to become a pseudocyst or a WON, respectively. Any collection subtype may become infected and manifest as internal gas, though this occurs most commonly in necrotic collections. In this review, the authors present a practical image-rich guide to the revised Atlanta classification system, with the goal of fostering implementation of the revised system into radiology practice, thereby facilitating accurate communication among clinicians and reinforcing the radiologist's role as a key member of a multidisciplinary team in treating patients with acute pancreatitis. (©)RSNA, 2016.

Direct MRI-guided biopsy of the prostate: use of post-biopsy needle track imaging to confirm targeting.

PURPOSE: To report the observation that in-plane post-biopsy T2-weighted MRI often demonstrates the needle track as a transient visible linear tissue distortion during direct MRI-guided biopsy. MATERIALS AND METHODS: We retrospectively identified 11 prostatic lesions in 9 men that underwent direct MRI-guided biopsy and in which post-biopsy images were obtained in the plane of the biopsy needle. RESULTS: In 9 of 11 targets, a post-biopsy needle track was visible as a linear tissue distortion on in-plane T2-weighted images obtained at a mean interval of 6 min (range 3-15). In these nine cases, the needle track traversed the intended target, and the biopsy was positive for malignancy in six. Biopsy was positive in one of two cases where the needle track was not visible. In five targets, one or more delayed series were obtained after a mean interval of 21 min (range 8-33), showing the track was no longer visible (n = 3) or was of progressively decreased conspicuity (n = 2). CONCLUSION: Accurate targeting during direct MRI-guided biopsy of the prostate can be confirmed by obtaining post-biopsy in-plane images, since the needle track is usually visible as a transient linear tissue distortion.

Endorectal MRI and MR spectroscopic imaging of prostate cancer: developing selection criteria for MR-guided focal therapy.

PURPOSE: To investigate criteria that can identify dominant treatable prostate cancer foci with high certainty at endorectal magnetic resonance imaging (MRI) and MR spectroscopic (MRS) imaging, and thus facilitate selection of patients who are radiological candidates for MR-guided focal therapy. MATERIALS AND METHODS: We retrospectively identified 88 patients with biopsy-proven prostate cancer who underwent endorectal MRI and MRS imaging prior to radical prostatectomy with creation of histopathological tumor maps. Two independent readers noted the largest tumor foci at MRI, if visible, and the volume of concordant abnormal tissue at MRS imaging, if present. A logistic random intercept model was used to determine the association between clinical and MR findings and correct identification of treatable (over 0.5 cm3) dominant intraprostatic tumor foci. RESULTS: Readers 1 and 2 identified dominant tumor foci in 50 (57%) and 58 (65%) of 88 patients; 42 (84%) and 48 (83%) of these were dominant treatable lesions at histopathology, respectively. Within the statistical model, the volume of concordant spectroscopic abnormality was the only factor that predicted correct identification of a dominant treatable lesion on T2-weighted images (odds ratio=1.75; 95% confidence interval=1.08 to 2.82; P value=0.02). In particular, all visible lesions on T2-weighted imaging associated with at least 0.54 cm3 of concordant spectroscopic abnormality were correctly identified dominant treatable tumor foci. CONCLUSION: Patients with dominant intraprostatic tumor foci seen on T2-weighted MRI and associated with at least 0.54 cm3 of concordant MRS imaging abnormality may be radiological candidates for MR-guided focal therapy.

Clinical utility of endorectal MRI-guided prostate biopsy: preliminary experience.

PURPOSE: To investigate the potential clinical utility of endorectal MRI-guided biopsy in patients with known or suspected prostate cancer. MATERIALS AND METHODS: We prospectively recruited 24 men with known or suspected prostate cancer in whom MRI-guided biopsy was clinically requested after multiparametric endorectal MRI showed one or more appropriate targets. One to six 18-gauge biopsy cores were obtained from each patient. Transrectal ultrasound guided biopsy results and post MRI-guided biopsy complications were also recorded. RESULTS: MRI-guided biopsy was positive in 5 of 7 patients with suspected prostate cancer (including 2 of 4 with prior negative ultrasound-guided biopsies), in 8 of 12 with known untreated prostate cancer (including 5 where MRI-guided biopsy demonstrated a higher Gleason score than ultrasound guided biopsy results), and in 3 of 5 with treated cancer. MRI-guided biopsies had a significantly higher maximum percentage of cancer in positive cores when compared with ultrasound guided biopsy (mean of 37 ± 8% versus 13 ± 4%; P = 0.01). No serious postbiopsy complications occurred. CONCLUSION: Our preliminary experience suggests endorectal MRI-guided biopsy may safely contribute to the management of patients with known or suspected prostate cancer by making a new diagnosis of malignancy, upgrading previously diagnosed disease, or diagnosing local recurrence.

Radiation-induced liver disease as a mimic of liver metastases at serial PET/CT during neoadjuvant chemoradiation of distal esophageal cancer.

PURPOSE: To determine the frequency and appearance of radiation-induced liver disease on PET/CT in patients undergoing serial imaging during neoadjuvant chemoradiation of distal esophageal cancer. MATERIALS AND METHODS: In this IRB-approved, HIPAA-compliant retrospective analysis, we identified 112 patients with distal esophageal cancer treated by neoadjuvant chemoradiation who had serial PET/CT imaging available for review. Two readers reviewed all studies in consensus and recorded those cases where new foci of visually detectable increased FDG avidity appeared in the liver during therapy. The etiology of such foci was determined from corresponding findings at CT or MRI, by hepatic biopsy during surgery, by characteristic evolution on post-operative imaging, or by a combination of these methods. RESULTS: New foci of FDG avidity developed in the liver during neoadjuvant therapy in 10 of 112 (9%) patients, of whom nine (8%) were determined to have radiation-induced liver disease based on further imaging and/or biopsy and one of whom had developed interval metastatic disease based on biopsy. In the cases of radiation-induced liver disease, the abnormal foci were found only in the caudate and left hepatic lobes, near the primary tumor, while the patient who developed interval metastatic disease had involvement of the inferior right hepatic lobe, remote from the radiation therapy field. CONCLUSION: New foci of increased FDG avidity are commonly seen in the caudate and left hepatic lobes of the liver during neoadjuvant chemoradiation of distal esophageal cancer, and these findings generally reflect radiation-induced liver disease rather than metastatic disease.

Targeted biopsy of the prostate.

Diagnostic multiparametric MRI of the prostate has steadily evolved over the last three decades and can now reliably depict the dominant tumor in most men with prostate cancer. In response, several methods of targeted biopsy to direct tissue sampling of suspected tumor foci seen at multiparametric MRI have been developed and successfully tested in recent years, including software-assisted MRI-ultrasound (US) fusion biopsy and direct MRI-guided in-bore biopsy. These advances are leading to a sea change in the approach to prostate cancer diagnosis, with the traditional approach of blind systematic biopsy increasingly being replaced by MRI directed targeted biopsy. This review aims to describe the current status of targeted biopsy, with an emphasis on the relative accuracy of different techniques. The results of several critical large multicenter trials are presented, while unanswered questions that require more research are highlighted.

Can CT features differentiate between inferior vena cava leiomyosarcomas and primary retroperitoneal masses?

OBJECTIVE: The objective of our study was to evaluate and describe CT features that may differentiate inferior vena cava (IVC) leiomyosarcomas from primary retroperitoneal masses. MATERIALS AND METHODS: A records search revealed 18 CT examinations with a soft-tissue mass contacting the IVC. Three readers evaluated the scans for four signs: an imperceptible IVC at the interface with the mass; a "positive embedded organ" sign (IVC embedded in the periphery of the mass); a "negative embedded organ" sign (IVC compressed at the perimeter of the mass); and tumor in the IVC lumen. CT findings were compared with pathology and operative reports. Performance and significance of CT features and interobserver agreement were calculated. RESULTS: Four of 18 (22%) retroperitoneal masses were IVC leiomyosarcomas. The IVC was imperceptible at the interface with the mass in three of the four (75%) IVC leiomyosarcomas (κ = 0.88) and in no alternate diagnosis (p < 0.02). No IVC leiomyosarcoma showed a positive embedded organ sign versus one of 14 masses of alternate origin (p = 1.0, κ = 0.56). The negative embedded organ sign was seen in most primary retroperitoneal masses (11/14 or 79%, κ = 0.85) but in no case of IVC leiomyosarcoma (p = 0.01). Intraluminal tumor was seen in one of four (25%) IVC leiomyosarcomas and in two of 14 other retroperitoneal masses (p = 1.0, κ = 1.0). CONCLUSION: An imperceptible IVC at the point of maximal contact with a retroperitoneal mass was the most useful CT feature for predicting the origin of IVC leiomyosarcoma. A negative embedded organ sign was useful for excluding IVC origin. Knowledge of these CT features may assist with preoperative planning.

Determinants of second-order bile duct visualization at CT cholangiography in potential living liver donors.

OBJECTIVE: The purpose of this article is to investigate the determinants of second-order bile duct visualization at CT cholangiography in living potential liver donors. MATERIALS AND METHODS: We retrospectively identified 143 potential living liver donors (83 men and 60 women; mean age, 37 years) evaluated with CT cholangiography, which included a slow infusion of iodipamide meglumine with CT acquisition 15 minutes after biliary contrast agent administration. Two readers independently scored the visualization of the second-order bile duct branches on a previously established 4-point scale (0 = not seen, 1 = faintly seen, 2 = well seen, and 3 = excellent visualization). Multivariate analysis was used to investigate the correlation between visualization scores and potential determinants of second-order bile duct opacification, specifically age, body mass index, creatinine level, total and direct bilirubin levels, alkaline phosphatase level, aspartate aminotransferase level, alanine aminotransferase level, patient maximum linear width, CT noise, and hepatosplenic attenuation difference at unenhanced CT. RESULTS: The mean (± SD) second-order bile duct visualization scores were 2.35 ± 0.66 and 2.55 ± 0.60 for readers 1 and 2, respectively. In the multivariate analysis, the only independent predictors of reduced second-order bile duct visualization were higher alkaline phosphatase level (p = 0.01) and higher CT noise (p = 0.02). CONCLUSION: Higher serum alkaline phosphatase level and higher CT noise in potential living liver donors indicate a higher risk of poor second-order bile duct visualization at CT cholangiography.

Pelvic applications of MR-guided high intensity focused ultrasound.

MR-guided high intensity focused ultrasound (MRg HIFU) is a novel method of tissue ablation that incorporates high energy focused ultrasound for tissue heating and necrosis within an MR scanner that provides simultaneous stereotactic tissue targeting and thermometry. To date, MRg HIFU has been used primarily to treat uterine fibroids, but many additional applications in the pelvis are in development. This article reviews the basic technology of MRg HIFU, and the use of MRg HIFU to treat uterine fibroids, adenomyosis, and prostate cancer.

The prevalence and patterns of intraluminal air in acute appendicitis at CT.

The purpose of this study is to investigate if the presence and distribution of intraluminal air in the appendix contributes to the computed tomography (CT) diagnosis of appendicitis. We identified 100 consecutive patients (57 men and 43 women; mean age, 38) with CT prior to appendectomy for acute appendicitis over a 5-year period and a control group of 100 consecutive patients (29 men and 71 women; mean age, 39) who underwent CT for acute abdominal pain without appendicitis. Patients were scanned using multidetector row CT scanners at 1.25 or 5-mm slice thickness, peak tube voltage of 120 kVp, and milliamperse automatically adjusted to attain a noise index of 12. Ninety-two of 100 study patients and 95 of 100 controls received 150 mL intravenous contrast. Two independent readers noted the presence and distribution pattern of intraluminal air in the appendix, appendiceal diameter, wall hyperemia, wall thickening (>3 mm), and wall stratification and presence of any secondary signs of appendicitis including fat stranding and free fluid. Data were compared between groups using Fisher's exact test and Student's t test. Intraluminal air in the appendix was more common in control patients versus patients with appendicitis (66 of 100 versus 27 of 100, p < 0.001). No significant differences in the patterns of intraluminal air were found between cases and controls. Among appendicitis cases, there was no significant difference in mean appendiceal diameter (12.8 versus 12.0, p = 0.20) or number of CT signs of appendicitis (1.93 versus 1.86, p = 0.78) in cases with intraluminal air versus without. No case of appendicitis demonstrated intraluminal air without secondary signs of appendicitis. Although intraluminal air is sometimes assumed to exclude a diagnosis of appendicitis, it is actually a common finding seen in up to 27 % of cases at CT. The pattern of intraluminal air was not helpful in differentiating a normal appendix from appendicitis.

Pancreatic imaging mimics: part 1, imaging mimics of pancreatic adenocarcinoma.

OBJECTIVE: The purpose of this article is to describe the imaging features of diseases that may closely simulate pancreatic adenocarcinoma, either radiologically or pathologically. CONCLUSION: Neoplastic and inflammatory diseases that can closely simulate pancreatic adenocarcinoma include neuroendocrine tumor, metastasis to the pancreas, lymphoma, groove pancreatitis, autoimmune pancreatitis, and focal chronic pancreatitis. Atypical imaging findings that should suggest diagnoses other than adenocarcinoma include the absence of significant duct dilatation, incidental detection, hypervascularity, large size (> 5 cm), IV tumor thrombus, and intralesional ducts or cysts.

Imaging of nontraumatic adrenal hemorrhage.

OBJECTIVE: The purpose of this pictorial essay is to review the imaging findings of acute, chronic, and tumor-related nontraumatic adrenal hemorrhage. CONCLUSION: Rapid development or evolution of a nonenhancing adrenal mass or masses with an adreniform shape or high T1 signal intensity on MR images of a patient under stress or with a bleeding diathesis, including anticoagulant use, suggests acute adrenal hemorrhage. Chronic hemorrhage appears as a thin-walled pseudocyst or atrophy. Imaging findings that may indicate underlying tumor include intralesional calcification, enhancement, and hypermetabolic activity on PET images.