Interreader Variability of Prostate Imaging Reporting and Data System Version 2 in Detecting and Assessing Prostate Cancer Lesions at Prostate MRI.

OBJECTIVE. The purpose of this study was to evaluate agreement among radiologists in detecting and assessing prostate cancer at multiparametric MRI using Prostate Imaging Reporting and Data System version 2 (PI-RADSv2). MATERIALS AND METHODS. Treatment-naïve patients underwent 3-T multipara-metric MRI between April 2012 and June 2015. Among the 163 patients evaluated, 110 underwent prostatectomy after MRI and 53 had normal MRI findings and transrectal ultrasound-guided biopsy results. Nine radiologists participated (three each with high, intermediate, and low levels of experience). Readers interpreted images of 58 patients on average (range, 56-60) using PI-RADSv2. Prostatectomy specimens registered to MRI were ground truth. Interob-server agreement was evaluated with the index of specific agreement for lesion detection and kappa and proportion of agreement for PI-RADS category assignment. RESULTS. The radiologists detected 336 lesions. Sensitivity for index lesions was 80.9% (95% CI, 75.1-85.9%), comparable across reader experience (p = 0.392). Patient-level specificity was experience dependent; highly experienced readers had 84.0% specificity versus 55.2% for all others (p < 0.001). Interobserver agreement was excellent for detecting index lesions (index of specific agreement, 0.871; 95% CI, 0.798-0.923). Agreement on PI-RADSv2 category assignment of index lesions was moderate (κ = 0.419; 95% CI, 0.238-0.595). For individual category assignments, proportion of agreement was slight for PI-RADS category 3 (0.208; 95% CI, 0.086-0.284) but substantial for PI-RADS category 4 (0.674; 95% CI, 0.540-0.776). However, proportion of agreement for T2-weighted PI-RADS 4 in the transition zone was 0.250 (95% CI, 0.108-0.372). Proportion of agreement for category assignment of index lesions on dynamic contrast-enhanced MR images was 0.822 (95% CI, 0.728-0.903), on T2-weighted MR images was 0.515 (95% CI, 0.430-0623), and on DW images was 0.586 (95% CI, 0.495-0.682). Proportion of agreement for dominant lesion was excellent (0.828; 95% CI, 0.742-0.913). CONCLUSION. Radiologists across experience levels had excellent agreement for detecting index lesions and moderate agreement for category assignment of lesions using PI-RADS. Future iterations of PI-RADS should clarify PI-RADS 3 and PI-RADS 4 in the transition zone.

What Are We Missing? False-Negative Cancers at Multiparametric MR Imaging of the Prostate.

Purpose To characterize clinically important prostate cancers missed at multiparametric (MP) magnetic resonance (MR) imaging. Materials and Methods The local institutional review board approved this HIPAA-compliant retrospective single-center study, which included 100 consecutive patients who had undergone MP MR imaging and subsequent radical prostatectomy. A genitourinary pathologist blinded to MP MR findings outlined prostate cancers on whole-mount pathology slices. Two readers correlated mapped lesions with reports of prospectively read MP MR images. Readers were blinded to histopathology results during prospective reading. At histopathologic examination, 80 clinically unimportant lesions (<5 mm; Gleason score, 3+3) were excluded. The same two readers, who were not blinded to histopathologic findings, retrospectively reviewed cancers missed at MP MR imaging and assigned a Prostate Imaging Reporting and Data System (PI-RADS) version 2 score to better understand false-negative lesion characteristics. Descriptive statistics were used to define patient characteristics, including age, prostate-specific antigen (PSA) level, PSA density, race, digital rectal examination results, and biopsy results before MR imaging. Student t test was used to determine any demographic differences between patients with false-negative MP MR imaging findings and those with correct prospective identification of all lesions. Results Of the 162 lesions, 136 (84%) were correctly identified with MP MR imaging. Size of eight lesions was underestimated. Among the 26 (16%) lesions missed at MP MR imaging, Gleason score was 3+4 in 17 (65%), 4+3 in one (4%), 4+4 in seven (27%), and 4+5 in one (4%). Retrospective PI-RADS version 2 scores were assigned (PI-RADS 1, n = 8; PI-RADS 2, n = 7; PI-RADS 3, n = 6; and PI-RADS 4, n = 5). On a per-patient basis, MP MR imaging depicted clinically important prostate cancer in 99 of 100 patients. At least one clinically important tumor was missed in 26 (26%) patients, and lesion size was underestimated in eight (8%). Conclusion Clinically important lesions can be missed or their size can be underestimated at MP MR imaging. Of missed lesions, 58% were not seen or were characterized as benign findings at second-look analysis. Recognition of the limitations of MP MR imaging is important, and new approaches to reduce this false-negative rate are needed. © RSNA, 2017 Online supplemental material is available for this article.

Computer-aided diagnosis prior to conventional interpretation of prostate mpMRI: an international multi-reader study.

OBJECTIVES: To evaluate if computer-aided diagnosis (CAD) prior to prostate multi-parametric MRI (mpMRI) can improve sensitivity and agreement between radiologists. METHODS: Nine radiologists (three each high, intermediate, low experience) from eight institutions participated. A total of 163 patients with 3-T mpMRI from 4/2012 to 6/2015 were included: 110 cancer patients with prostatectomy after mpMRI, 53 patients with no lesions on mpMRI and negative TRUS-guided biopsy. Readers were blinded to all outcomes and detected lesions per PI-RADSv2 on mpMRI. After 5 weeks, readers re-evaluated patients using CAD to detect lesions. Prostatectomy specimens registered to MRI were ground truth with index lesions defined on pathology. Sensitivity, specificity and agreement were calculated per patient, lesion level and zone-peripheral (PZ) and transition (TZ). RESULTS: Index lesion sensitivity was 78.2% for mpMRI alone and 86.3% for CAD-assisted mpMRI (p = 0.013). Sensitivity was comparable for TZ lesions (78.7% vs 78.1%; p = 0.929); CAD improved PZ lesion sensitivity (84% vs 94%; p = 0.003). Improved sensitivity came from lesions scored PI-RADS < 3 as index lesion sensitivity was comparable at PI-RADS ≥ 3 (77.6% vs 78.1%; p = 0.859). Per patient specificity was 57.1% for CAD and 70.4% for mpMRI (p = 0.003). CAD improved agreement between all readers (56.9% vs 71.8%; p < 0.001). CONCLUSIONS: CAD-assisted mpMRI improved sensitivity and agreement, but decreased specificity, between radiologists of varying experience. KEY POINTS: • Computer-aided diagnosis (CAD) assists clinicians in detecting prostate cancer on MRI. • CAD assistance improves agreement between radiologists in detecting prostate cancer lesions. • However, this CAD system induces more false positives, particularly for less-experienced clinicians and in the transition zone. • CAD assists radiologists in detecting cancer missed on MRI, suggesting a path for improved diagnostic confidence.

Validation of the Dominant Sequence Paradigm and Role of Dynamic Contrast-enhanced Imaging in PI-RADS Version 2.

Purpose To validate the dominant pulse sequence paradigm and limited role of dynamic contrast material-enhanced magnetic resonance (MR) imaging in the Prostate Imaging Reporting and Data System (PI-RADS) version 2 for prostate multiparametric MR imaging by using data from a multireader study. Materials and Methods This HIPAA-compliant retrospective interpretation of prospectively acquired data was approved by the local ethics committee. Patients were treatment-naïve with endorectal coil 3-T multiparametric MR imaging. A total of 163 patients were evaluated, 110 with prostatectomy after multiparametric MR imaging and 53 with negative multiparametric MR imaging and systematic biopsy findings. Nine radiologists participated in this study and interpreted images in 58 patients, on average (range, 56-60 patients). Lesions were detected with PI-RADS version 2 and were compared with whole-mount prostatectomy findings. Probability of cancer detection for overall, T2-weighted, and diffusion-weighted (DW) imaging PI-RADS scores was calculated in the peripheral zone (PZ) and transition zone (TZ) by using generalized estimating equations. To determine dominant pulse sequence and benefit of dynamic contrast-enhanced (DCE) imaging, odds ratios (ORs) were calculated as the ratio of odds of cancer of two consecutive scores by logistic regression. Results A total of 654 lesions (420 in the PZ) were detected. The probability of cancer detection for PI-RADS category 2, 3, 4, and 5 lesions was 15.7%, 33.1%, 70.5%, and 90.7%, respectively. DW imaging outperformed T2-weighted imaging in the PZ (OR, 3.49 vs 2.45; P = .008). T2-weighted imaging performed better but did not clearly outperform DW imaging in the TZ (OR, 4.79 vs 3.77; P = .494). Lesions classified as PI-RADS category 3 at DW MR imaging and as positive at DCE imaging in the PZ showed a higher probability of cancer detection than did DCE-negative PI-RADS category 3 lesions (67.8% vs 40.0%, P = .02). The addition of DCE imaging to DW imaging in the PZ was beneficial (OR, 2.0; P = .027), with an increase in the probability of cancer detection of 15.7%, 16.0%, and 9.2% for PI-RADS category 2, 3, and 4 lesions, respectively. Conclusion DW imaging outperforms T2-weighted imaging in the PZ; T2-weighted imaging did not show a significant difference when compared with DW imaging in the TZ by PI-RADS version 2 criteria. The addition of DCE imaging to DW imaging scores in the PZ yields meaningful improvements in probability of cancer detection. © RSNA, 2017 An earlier incorrect version of this article appeared online. This article was corrected on July 27, 2017. Online supplemental material is available for this article.

Does Abstinence From Ejaculation Before Prostate MRI Improve Evaluation of the Seminal Vesicles?

OBJECTIVE: The purpose of the present study is to determine whether abstinence from ejaculation before undergoing multiparametric prostate MRI increases seminal vesicle (SV) volume and therefore improves diagnostic interpretation of the SVs. MATERIALS AND METHODS: This retrospective study included 238 patients who underwent 3-T MRI of the prostate over a 4-month period. Patients were requested to complete a questionnaire that asked how long it had been since their last ejaculation (i.e., < 3 days vs ≥ 3 days). Forty-two patients (mean patient age, 62.0 years) indicated that it had been less than 3 days since their last ejaculation and were designated as group 1, whereas the remainder indicated an interval of 3 days or more since their last ejaculation. A group of 42 age-matched subjects (mean patient age, 62.1 years) were randomly selected from the remaining 196 patients and were designated as group 2. SV volumes were measured manually. Two radiologists who were blinded to group assignment and patient characteristics scored the right and left SVs separately to determine diagnostic interpretability, which was scored on a 3-point scale as follows: a score of 1 denoted that the SVs were not dilated and the score was nondiagnostic, a score of 2 indicated that the SVs were not dilated but the score was diagnostic, and a score of 3 denoted that the SVs were dilated and the score was diagnostic. Volume differences and interpretability scores were analyzed using a t test. Interobserver agreement was analyzed using the Cohen kappa statistic. A separate analysis was performed to evaluate differences in diagnostic interpretability for patients 60 years and younger versus patients older than 60 years, by use of the chi-square test and relative risk ratio analysis. RESULTS: The right, left, and total SV volumes for group 1 were 3.1 mL, 2.9 mL, and 6.0 mL, respectively, whereas those for group 2 were 4.7 mL, 4.1 mL, and 8.8 mL, respectively (p = 0.011). The mean interpretability scores for group 1 and group 2 were 2.0 and 2.5, respectively. For group 1, reader 1 and reader 2 assigned a nondiagnostic score for 10 and 13 patients, respectively, whereas for group 2, they assigned a nondiagnostic score for two and five patients, respectively (p = 0.01, for reader 1; and p = 0.03, for reader 2). For men in group 1 who were older than 60 years, reader 1 and reader 2 gave a nondiagnostic score for nine and 11 patients, respectively; whereas for men in group 2 who were older than 60 years, the readers gave a nondiagnostic score for two and five patients, respectively (p = 0.01, for reader 1; and p = 0.05, for reader 2). CONCLUSION: For men older than 60 years, abstinence from ejaculation for 3 or more days before undergoing MRI examination resulted in larger SV volumes and lower rates of nondiagnostic evaluation and therefore might improve evaluation of SV invasion on multi-parametric MRI. The difference is less striking in men 60 years and younger.

Multiparametric MRI of the prostate gland: technical aspects.

With recent technological advancements, multiparametric MRI (mpMRI) has evolved into an important tool in the detection, localization and staging of prostate cancer. Optimization of image quality is paramount to mpMRI technique. While PI-RADS version 2 established guidelines for minimum technical parameters, there is no uniformity in mpMRI protocols across institutions. This review will discuss the key sequences that comprise a mpMRI exam. Technical factors that affect image quality, such as pre-exam patient preparation, magnet field strength, endorectal coil utilization and sequence parameters will also be examined. Several emerging technologies with potential to aid in the maturation of mpMRI will be introduced.

Small subdural hemorrhages: is routine intensive care unit admission necessary?

With advancing technology, the sensitivity of computed tomography (CT) for the detection of subdural hematoma (SDH) continues to improve. In some cases, the finding is limited to one or 2 images of the CT examination. At our institution, all patients with an SDH require intensive care unit (ICU) admission, regardless of size. In this report, we tested the hypothesis that patients with a small traumatic SDH on their presenting CT examination do not require the intensive monitoring offered in the ICU and can instead be managed on a hospital unit with a lower level of monitoring. This is a retrospective study of patients evaluated and treated at a level I trauma center for acute traumatic intracranial hemorrhage between 2011 and 2014. The clinical and imaging profile of 87 patients with traumatic SDH were studied. Patients with small isolated traumatic subdural hemorrhage (tSDH) (<10 cm(3) blood volume) spent less time in the ICU, demonstrated neurologic and medical stability during hospitalization, and did not require any neurosurgical intervention. It is our recommendation that patients with isolated tSDH (<10 cm(3)) do not require ICU monitoring. Patients with small tSDH and additional intracranial hemorrhages overall show low rates of medical decline (4%) and neurologic decline (4%) but may still benefit from ICU observation. Patients with tSDH greater than 10 cm(3) overall demonstrated poor clinical courses and outcome and would benefit ICU monitoring.

The clinical significance of small subarachnoid hemorrhages.

With advancing technology, the sensitivity of computed tomography (CT) for the detection of traumatic subarachnoid hemorrhage (tSAH) continues to improve. Increased resolution has allowed for the detection of hemorrhage that is limited to one or two images of the CT exam. At our institution, all patients with a SAH require intensive care unit (ICU) admission, regardless of size. It was our hypothesis that patients with small subarachnoid hemorrhage experience favorable outcomes, and may not require the intensive monitoring offered in the ICU. This retrospective study evaluated 62 patients between 2011 and 2014 who presented to our Level I trauma center emergency room for acute traumatic injuries, and found to have subarachnoid hemorrhages on CT examination. The grade of subarachnoid hemorrhage was determined using previously utilized scoring systems, such as the Fisher, Modified Fisher, and Claassen grading systems. Electronic medical records were used to evaluate for medical decline, neurological decline, neurosurgical intervention, and overall hospital course. Admitting co-morbidities were noted, as were the presence of patient intoxication and use of anticoagulants. Patient outcomes were based on discharge summaries upon which the neurological status of the patient was assessed. Each patient was given a score based on the Glasgow outcome scale. The clinical and imaging profile of 62 patients with traumatic SAH were studied. Of the 62 patients, 0 % underwent neurosurgical intervention, 6.5 % had calvarial fractures, 25.8 % had additional intracranial hemorrhages, 27.4 % of the patients had significant co-morbidities, and 1.6 % of the patients expired. Patients with low-grade tSAH spent less time in the ICU, demonstrated neurological and medical stability during hospitalization. None of the patients with low-grade SAH experienced seizure during their admission. In our study, patients with low-grade tSAH demonstrated favorable clinical outcomes. This suggests that patients may not require as aggressive monitoring as is currently provided for those with tSAH.

Transiliopsoas approach: an alternative route to drain pelvic abscesses in children.

OBJECTIVE: To evaluate an alternative route of pelvic abscess drainage in children via a transiliopsoas approach. BACKGROUND: Appendiceal perforations complicated by inflammatory masses, such as abscesses or phlegmon, are a common indication for abdominal drainage in pediatric interventional radiology. Certain locations of collections may present particular challenges for the operator, owing to numerous surrounding structures, including bowel and other pelvic anatomy. This series describes an alternative route for drainage, which involves traversing the iliopsoas muscle under US guidance to drain a deep pelvic abscess. MATERIALS AND METHODS: Retrospective chart review was performed of the transiliopsoas approach for abscess drainage during a 5-year period. The technique, pre- and post-drainage imaging, aspiration/drain output, duration of catheter dwell, procedure-related complications and abscess recurrence were reviewed. RESULTS: Transiliopsoas needle placement was successful in 14 of 14 patients (100%). Catheter placement was successful in 13 patients. Abscess wall rupture precluded catheter placement in one patient. Mean catheter duration was 4.9 days, with a range of 2 to 9 days. Clinical improvement was achieved in all 14 patients (100%). There were no major complications. Post-procedure pain with ambulation was reported in 3 of 14 patients (21.4%), which was successfully controlled in each case with medication, and resolved after 2 days. CONCLUSION: The transiliopsoas route is a safe and effective route for US-guided abscess drainage and catheter placement in children with deep pelvic collections. In selected cases, this approach provides a more easily accessible and safer route than more traditional interventional approaches.

The emergency room diagnosis of gastrointestinal tract perforation: the role of CT.

Computed tomography (CT) plays an important role in the evaluation of patients presenting to the emergency department with a suspected spontaneous gastrointestinal tract (GIT) perforation. Prospective identification of the site of perforation helps the emergency department physician plan the appropriate treatment in a potentially unstable patient. The purpose of this pictorial essay is to review the CT approach a radiologist should take when evaluating the patient with suspected perforation in the emergent setting. A series of patients presenting to the emergency department with surgically proven GIT perforations were retrospectively reviewed, and key images were obtained. For the purposes of this review, the anatomy of the abdominal cavity in relation to sites of GIT perforation will be discussed. CT findings of perforation will be described, including free intraperitoneal/extraperitoneal air, bowel wall discontinuity, and localized inflammatory changes. The use of a bone window setting to increase the free air conspicuity will be emphasized. The mimics of pneumoperitoneum will be demonstrated, including pneumothorax, pneumomediastinum, and venous air. Using a systematic approach, CT can precisely determine the presence and site of a gastrointestinal perforation in a majority of patients. This greatly assists the surgeon in planning the correct surgical approach.

Bevacizumab-induced perforation of the gastrointestinal tract: clinical and radiographic findings in 11 patients.

AIM: To present the gastrointestinal (GI) complications associated with bevacizumab therapy and their findings on abdominal imaging studies. METHODS: A computerized search identified 11 patients with GI complications of bevacizumab therapy on abdominal CT (n = 11) and fluoroscopic GI contrast studies (n = 4) who met our study criteria (including five patients with ovarian cancer, five with colon cancer, and one with cervical cancer). The medical records and imaging studies were reviewed to determine the clinical and radiographic findings in these patients. RESULTS: All 11 patients had findings of GI perforation on CT, or CT and GI contrast studies. CT revealed a localized extraluminal collection containing gas, fluid, and/or contrast material in eight patients (73%) with focal perforation, and free abdominal air and fluid in three (27%) with free perforation The imaging studies also revealed seven fistulas, including two colovaginal, one rectovaginal, one enterocutaneous, one colocutaneous, one gastrocolic, and one colorectal fistula. Eight (73%) of the 11 patients died within 1 year of the development of GI perforation, and the perforation was felt to be the cause of death in four patients (36%). CONCLUSION: Abdominal CT and fluoroscopic GI contrast studies are useful imaging tests for the diagnosis of potentially life-threatening GI perforation as a complication of bevacizumab therapy. When GI perforation is detected on abdominal imaging studies, treatment with bevacizumab should immediately be discontinued.

Application of partial volume effect correction and 4D PET in the quantification of FDG avid lung lesions.

PURPOSE: The aim of this study is to assess a software-based method with semiautomated correction for partial volume effect (PVE) to quantify the metabolic activity of pulmonary malignancies in patients who underwent non-gated and respiratory-gated 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG)-positron emission tomography (PET)/x-ray computed tomography(CT). PROCEDURES: The study included 106 lesions of 55 lung cancer patients who underwent respiratory-gated FDG-PET/CT for radiation therapy treatment planning. Volumetric PET/CT parameters were determined by using 4D PET/CT and non-gated PET/CT images. We used a semiautomated program employing an adaptive contrast-oriented thresholding algorithm for lesion delineation as well as a lesion-based partial volume effect correction algorithm. We compared respiratory-gated parameters with non-gated parameters by using pairwise comparison and interclass correlation coefficient assessment. In a multivariable regression analysis, we also examined factors, which can affect quantification accuracy, including the size of lesion and the location of tumor. RESULTS: This study showed that quantification of volumetric parameters of 4D PET/CT images using an adaptive contrast-oriented thresholding algorithm and 3D lesion-based partial volume correction is feasible. We observed slight increase in FDG uptake by using PET/CT volumetric parameters in comparison of highest respiratory-gated values with non-gated values. After correction for partial volume effect, the mean standardized uptake value (SUVmean) and total lesion glycolysis (TLG) increased substantially (p value <0.001). However, we did not observe a clinically significant difference between partial volume corrected parameters of respiratory-gated and non-gated PET/CT scans. Regression analysis showed that tumor volume was the main predictor of quantification inaccuracy caused by partial volume effect. CONCLUSIONS: Based on this study, assessment of volumetric PET/CT parameters and partial volume effect correction for accurate quantification of lung malignant lesions by using respiratory non-gated PET images are feasible and it is comparable to gated measurements. Partial volume correction increased both the respiratory-gated and non-gated values significantly and appears to be the dominant source of quantification error of lung lesions.

Dysembryoplastic neuroepithelial tumor with atypical presentation: MRI and diffusion tensor characteristics.

We report the neuroimaging findings of a 26-year-old female patient with a biopsy-proven dysembryoplastic neuroepithelial tumor (DNET). DNETs are an uncommon, usually benign, glial-neural cortical neoplasm of children and young adults who typically present with intractable seizures. DNETs may occur in any region of the supratentorial cortex, but have a predilection for the temporal lobes. Accurate neuroimaging diagnosis is essential since patients with DNET benefit from complete resection. However, accurate differentiation from other cortical lesions may be challenging. Typical conventional Magnetic Resonance Imaging (MRI) features can help in the differentiation from other similar cortical tumors. Diffusion tensor imaging can also provide important additional diagnostic information regarding the degree of involvement of adjacent parenchyma and white matter tracts. In this case, tractography and fractional anisotropy maps demonstrated that fiber tracts surrounding the lesion were displaced, but fiber integrity was maintained, which is more suggestive of a DNET rather than a more aggressive neoplasm. Accurate identification of DNETs is essential for the purpose of rendering a timely diagnosis and start appropriate treatment.