MRI-Based Tumor Necrosis Depiction in Pancreatic Ductal Adenocarcinoma: Can It Predict Tumor Aggressiveness?

The purpose of this study was to investigate whether tumor necrosis depicted on contrast-enhanced abdominal MRI can predict tumor aggressiveness in pancreatic ductal adenocarcinoma (PDAC). In this retrospective analysis, we included 71 patients with pathology-proven PDAC who underwent contrast-enhanced MRI from 2006 to 2020. Assessment for the presence/absence of imaging detected necrosis was performed on T2-weighted and contrast-enhanced T1-weighted images. Primary tumor characteristics, regional lymphadenopathy, metastases, stage, and overall survival were analyzed. Fisher's exact and Mann-Whitney U tests were used for statistical analysis. Of the 72 primary tumors, necrosis was identified on MRI in 58.3% (42/72). Necrotic PDACs were larger (44.6 vs. 34.5 mm, p = 0.0016), had higher rates of regional lymphadenopathy (69.0% vs. 26.7%, p = 0.0007), and more frequent metastases (78.6% vs. 40.0%, p = 0.0010) than those without MRI-evident necrosis. A non-statistically significant reduction in median overall survival was observed in patients with versus without MRI-evident necrosis (15.8 vs. 38.0 months, p = 0.23). PDAC tumor necrosis depicted on MRI was associated with larger tumors and higher frequency of regional lymphadenopathy and metastases.

Cardiac Incidental Findings on Abdominopelvic Computed Tomography: Prevalence and Association with Subsequent Cardiovascular Events.

PURPOSE: The aim of this study was to assess the prevalence of reportable cardiac findings detected on abdominopelvic CTs and the association with subsequent cardiovascular events. MATERIALS AND METHODS: We performed a retrospective search of electronic medical record of patients who underwent abdominopelvic CT between November 2006 and November 2011 with a clinical history of upper abdominal pain. A radiologist blinded to the original CT report reviewed all 222 cases for the presence of pertinent reportable cardiac findings. The original CT report was also evaluated for documentation of pertinent reportable cardiac findings. The following findings were recorded on all CTs: presence of coronary calcification, fatty metaplasia, ventricle wall thinning and thickening, valve calcification or prosthesis, heart/chamber enlargement, aneurysm, mass, thrombus, device, air within ventricles, abnormal pericardium, prior sternotomy, and adhesions if prior sternotomy. Medical records were reviewed to identify cardiovascular events on follow-up in patients with the presence or absence of cardiac findings. We compared the distribution findings in patients with and without cardiac events using the Wilcoxon test (for continuous variables) and the Pearson's chi-squared test (for categorical variables). RESULTS: Eighty-five of 222 (38.3%) patients (52.7% females, median age 52.5 years) had at least one pertinent reportable cardiac finding on the abdominopelvic CT, with a total of 140 findings in this group. From the total 140 findings, 100 (71.4%) were not reported. The most common findings seen on abdominal CTs were: coronary artery calcification (66 patients), heart or chamber enlargement (25), valve abnormality (19), sternotomy and surgery signs (9), LV wall thickening (7), device (5), LV wall thinning (2), pericardial effusion (5), and others (3). After a mean follow-up of 43.9 months, 19 cardiovascular events were found in the cohort (transient ischemic attack, cerebrovascular accident, myocardial infarction, cardiac arrest, acute arrhythmia, palpitation, syncope and acute chest pain). Only 1 event occurred in the group of patients with no incidental pertinent reportable cardiac findings (1/137 = 0.73%). All other 18 events occurred in patients with incidental pertinent reportable cardiac findings (18/85 = 21.2%), which was significantly different (p < 0.0001). One out of the total 19 events in the overall group (5.24%) occurred in a patient with no incidental pertinent reportable cardiac findings while 18 of 19 total events (94.74%) occurred with patients with incidental pertinent reportable cardiac findings, which was also significantly different (p < 0.001). Fifteen of the total events (79%) occurred in patients in whom the incidental pertinent reportable cardiac findings were not reported, which was significantly different (p < 0.001) from the four events that occurred in patients in whom the incidental pertinent reportable cardiac findings were reported or had no findings. CONCLUSIONS: Incidental pertinent reportable cardiac findings are common on abdominal CTs and are frequently not reported by radiologists. These findings are of clinical relevance since patients with pertinent reportable cardiac findings have a significantly higher incidence of cardiovascular events on follow-up.

Imaging Utilization Patterns and Injury Characteristics Associated with Electric Standing Scooters in a Major Urban Area.

BACKGROUND: The recent proliferation of electric standing scooters in major urban areas of the United States has been accompanied by injuries of varying severity and nature, representing a growing public health concern. OBJECTIVE: Our aim was to characterize imaging utilization patterns for injuries associated with electric scooter (e-scooter) use, including their initial emergency department (ED) management. METHODS: We conducted a retrospective review of the electronic medical record for all patients presenting to affiliated EDs for e-scooter-related injuries between July 2018 and April 2020. Demographics, date and time of presentation, imaging study type, resultant injury, and procedural details were recorded. RESULTS: Ninety-seven patients were included; mean age was 27.6 years. Of these, 55 patients (57%) had injuries identified on imaging and 40% of all imaging studies were positive. Most identified injuries (61%) were musculoskeletal, with a small number of neurological (2%) and genitourinary (1%) injuries. The highest prevalence of presentations occurred in August; most patients (72%) presented between 3 pm and 1 am and granular peaks were between 12 am and 1 am and 5 pm and 6 pm. CONCLUSIONS: Patients presenting with e-scooter injuries have a high likelihood of injury to the radial head, nasal bone, and malleoli. Emergency physicians should be especially vigilant for injuries in these areas at presentation. Visceral injuries are uncommon but may be severe enough to warrant surgery.

Computed tomography findings of metabolic syndrome in patients with acute colonic diverticulitis.

INTRODUCTION: Many factors associated with colonic diverticulitis are also part of the clinical definition of the metabolic syndrome. Computed tomography (CT) is commonly performed in symptomatic patients, such as those with suspected or known acute diverticulitis, and could add additional value for the health of these patients by identifying and reporting CT biomarkers of metabolic syndrome, if present and detectable. The purpose of this study was to identify CT biomarkers of metabolic syndrome in patients with acute colonic diverticulitis. METHODS: We retrospectively reviewed 243 patients (mean-60 yrs, M:F:126:117) diagnosed with colonic diverticulitis on CT between March 2015 and March 2017 for hepatic steatosis, vascular calcifications, abdominal diameters and fat volumes. Criteria of metabolic syndrome were obtained from medical records. Differences in imaging biomarkers were compared using chi-square comparisons stratified by metabolic syndrome, abdominal diameter and fat volume. RESULTS: Of 243 patients, 33% demonstrated hepatic steatosis and 71% atherosclerotic vascular calcifications on CT. 28% met criteria for metabolic syndrome. Patients with metabolic syndrome had higher occurrence of hepatic steatosis, sagittal diameter ≥ 35 cm, visceral fat > 5000 cm3 and subcutaneous fat > 8300 cm3 (P < 0.05), but not vascular calcifications (P > 0.05). CONCLUSIONS: CT biomarkers of metabolic syndrome are commonly encountered in patients with acute diverticulitis. Recognizing and reporting these findings can guide towards further evaluation for metabolic syndrome.

Hepatobiliary contrast uptake patterns on gadoxetic acid-enhanced MRI in liver metastases from pancreatic ductal adenocarcinoma: can it predict prognosis?

OBJECTIVES: To evaluate the relationship between the patterns of hepatobiliary phase (HBP) contrast uptake in liver metastases on gadoxetic acid-enhanced MR imaging and overall survival (OS) in patients with pancreatic ductal adenocarcinoma (PDAC). METHODS: This retrospective study was approved by our institutional review board and written informed consent was waived. A total of 57 patients (30 men and 27 women; age range, 46-92 years; mean age, 64.9 ± 9.2 years) with PDAC and liver metastasis who had undergone gadoxetic acid-enhanced MR imaging were included. The internal morphologies of the nodules were classified as heterogeneous or homogeneous on HBP images (20 min). During patient-by-patient analysis, patients with both patterns of nodules were classified as belonging to the heterogeneous group. Kaplan-Meier analysis and log-rank test were conducted for univariate analysis and Cox proportional hazards regression was conducted for multivariate analysis to evaluate prognostic factors for OS in patients with PDAC and liver metastasis. RESULTS: A total of 199 liver metastases were analyzed, among which 138 nodules (69%) demonstrated heterogeneous hypointensity, while 61 nodules (31%) demonstrated homogeneous hypointensity. Homogeneous hypointense nodules were encountered in 18 patients (32%; homogeneous group), heterogeneous in 29 patients (51%), and both patterns co-existed in 10 patients (17%; heterogeneous group). The heterogeneous group exhibited lower OS rates than the homogeneous group (mean OS, 48.5 months vs 23.9 months; p = 0.032). CONCLUSIONS: Hepatobiliary contrast uptake pattern in liver metastasis on HBP images can be a potential imaging biomarker to predict OS in patients with PDAC and liver metastasis. KEY POINTS: • Majority of the liver metastases were heterogeneous (69%) after gadoxetic acid-enhanced MR imaging. • Patients with heterogeneous hypointense nodules demonstrated lower overall survival rate. • Hepatobiliary contrast uptake pattern in liver metastasis is possibly associated with patients' prognosis.

Hepatobiliary phase enhancement of liver metastases on gadoxetic acid MRI: assessment of frequency and patterns.

OBJECTIVES: To assess for and characterize patterns of hepatobiliary phase (HBP) enhancement in hepatic metastases of various malignancies on gadoxetic acid-enhanced MRI. METHODS: Eighty gadoxetic acid-enhanced MRI studies performed between July 2012 and November 2019 in patients with hepatic metastases from 13 different primary malignancies were assessed. Most (n = 60) were from colorectal cancer (CRC), pancreatic ductal adenocarcinoma (PDAC), or neuroendocrine tumor (NET) primaries. Two radiologists quantitatively evaluated the dominant lesion on each MRI. A lesion was considered enhancing when HBP enhancement relative to muscle exceeded 20%. Lesions were classified by pattern of enhancement. Quantitative enhancement metrics and patterns of enhancement were compared between CRC, PDAC, and NET using non-parametric statistical tests. RESULTS: Most dominant metastatic lesions > 1 cm (77%, 54/70) demonstrated HBP enhancement. HBP enhancement was identified in hepatic metastases from 10 different primary malignancies, including CRC, PDAC, and NET. PDAC metastases demonstrated a lower degree of HBP enhancement (26%) than CRC (44%, padj = 0.04) and NET (51%, padj = 0.01) metastases. Three discrete enhancement patterns were identified: peripheral, central (target), and diffuse heterogeneous. Patterns of HBP enhancement varied between CRC, PDAC, and NET, with secondary analysis demonstrating that PDAC had the highest proportion of peripheral pattern (73%, padj < 0.001), CRC the highest proportion of diffuse heterogeneous pattern (32%, padj < 0.01), and NET the highest proportion of central pattern (89%, padj < 0.001). CONCLUSION: Liver metastases from several primary malignancies, including PDAC, demonstrate mild HBP enhancement in variable patterns. Correlation with OATP1B3 expression and prognosis is required. KEY POINTS: • Hepatobiliary phase (HBP) enhancement was identified in 77% of hepatic metastases in several different primary malignancies. • Discrete patterns of HBP enhancement exist (peripheral, central, diffuse heterogeneous) and varied between CRC, PDAC, and NET. CRC and PDAC metastases demonstrated mostly non-central patterns (diffuse and peripheral), and NET mostly a central pattern. • Relationship between HBP enhancement, enhancement pattern, OATP1B3 expression, and prognosis requires further dedicated exploration for each malignancy.

Imaging predictors of BRAF mutation in colorectal cancer.

BACKGROUND: Colorectal cancer (CRC) is one of the leading causes of cancer deaths and is associated with various genetic mutations. BRAF mutations, found in approximately 10% of all CRCs, are associated with negative predictive outcomes. The goal of this study was to assess the relationship between the imaging findings and BRAF statuses of CRC patients. MATERIALS AND METHODS: The study population was colorectal cancer patients who underwent biopsy or surgery in a single institution from September 2004 to October 2018, and in whom the pathologic specimens were tested for BRAF mutation. The exclusion criteria were (1) patients without pre-operative cross-sectional imaging, and (2) patients whose tumors were invisible on imaging. Two hundred and eighty-three patients met the inclusion criteria. Among them, 128 were excluded, and a total of 155 patients were enrolled in the study. RESULTS: BRAF mutations were significantly more common in female patients (p = 0.007). Patients with mutated BRAF were significantly older than those with wild-type BRAF (p = 0.001). BRAF-mutant tumors were predominant in right-sided colon (p = 0.001) with higher numbers of polypoid- or mass-like morphology (p = 0.019) and heterogeneous enhancement (p = 0.009). Compared to their wild-type counterparts, BRAF-mutated CRCs have a lower occurrence of non-peritoneal, and overall metastases (p = 0.013 and p = 0.004, respectively). Logistic regression analysis showed three significant factors for the prediction of BRAF mutations in CRC patients: right-sided location (p = 0.002), heterogeneous tumor enhancement (p = 0.039), and lack of non-peritoneal metastasis (p = 0.043). CONCLUSION: By recognizing the specific imaging features of BRAF-mutant CRCs, it would be possible to identify a patient who has a higher risk of carrying BRAF mutation.

Rapid kVp-switching DECT portal venous phase abdominal CT scans in patients with large body habitus: image quality considerations.

PURPOSE: To assess the diagnostic image quality and material decomposition characteristics of portal venous phase abdominal CT scans performed on rapid kVp-switching DECT (rsDECT) in patients with large body habitus. METHODS: We retrospectively included consecutive patients with large body habitus (≥ 90 kg) undergoing portal venous phase abdominal CT scans on rsDECT scanners between Sep 2014 and March 2018. Qualitative and quantitative assessment of the DECT data sets [65 keV monoenergetic, material density iodine (MD-I) and material density water (MD-W) images] was performed for determination of image quality (IQ) and image noise. Correlation of qualitative assessment scores with weight, BMI and patients' diameter were calculated using Pearson correlation test. Optimal thresholds were calculated using AUC and Youden index to define most appropriate size cut off, below which the IQ of material density images is largely acceptable. RESULTS: The 65 keV monoenergetic images were of diagnostic quality (diagnostic acceptability, DA ≥ 3) in 97.8% of patients (n = 91/93). However, there was significant IQ degradation of MD-I images in 20.4% (n = 19/93, DA < 3) of patients. Similarly, there was significant degradation (DA < 3) of MD-W images in 26.9% (25/92). Clinically significant artifacts (PA ≥ 3/4) were seen in 31% (n = 29/93) and 32.3% (30/93) of MD-I and MD-W images respectively. Optimal threshold for diagnostic acceptability of MD-I images were 110 kg for weight and 33.5 kg/m2 for BMI. CONCLUSION: Rapid kVp-switching DECT provides diagnostically acceptable monoenergetic images for patients with large body habitus (≥ 90 kg). There is degradation of IQ in the material density specific images particularly in patients weighing > 110 kg and with BMI > 33.5 kg/m2, due to higher number of artifacts.

Pictorial review on abdominal applications of ferumoxytol in MR imaging.

Though gadolinium-based contrast agents are the most widely used contrast media in MR for clinical use, problems with nephrogenic systemic fibrosis and tissue deposition render their safety debatable, at least in a selected patient population. Ferumoxytol has the potential to be used as an alternate contrast medium for various clinical applications across multiple organs. It has prolonged intravascular signal and delayed intracellular macrophage uptake which are unique properties compared to gadolinium-based agents. This pictorial review aims to review the current and potential clinical applications of ferumoxytol as a contrast agent in abdominal MR imaging.

Can magnetic resonance imaging differentiate among transurethral bulking agent, urethral diverticulum, and periurethral cyst?

PURPOSE: To evaluate magnetic resonance imaging findings that differentiate among periurethral bulking agents (primarily collagen), urethral diverticulum, and periurethral cyst. METHODS: We searched our radiologic database retrospectively from 2001 to 2017 for periurethral cystic lesions, identifying a total of 50 patients with 68 lesions. Final diagnoses in 68 lesions were bulking agents (27), urethral diverticula (29), and periurethral cysts (12). Two abdominal radiologists, blinded to clinical history, independently evaluated T1, T2, and post-contrast images. The readers assessed number, morphological features, location, connection to urethra and mass effect, signal intensity, and enhancement for each lesion. Fisher exact test and logistic regression analysis were performed for each univariate significant feature. The operative and pathologic reports were the reference standard. RESULTS: Magnetic resonance imaging features found more often in bulking agents versus urethral diverticulum were multiple lesions (P = 0.011), upper or upper-mid-urethral location (P ≤ 0.0001), lack of internal fluid/fluid level (P = 0.002), no urethral connection (P = 0.005), T1 isointensity, and T2 mild hyperintensity compared to muscles but lower T2 signal than urine (P < 0.0001). Most cases of urethral diverticula and periurethral cysts were detected at mid- and lower urethra. Urethral diverticula were larger than bulking agents and periurethral cysts (P = 0.005 and P = 0.023) (mean diameter = 24, 16, 15 mm, respectively). Most bulking agents (93%) and urethral diverticula (90%) showed mass effect on urethra, while periurethral cysts (75%) did not (P < 0.0001). CONCLUSION: Signal intensity and lesion characterization on magnetic resonance imaging can significantly differentiate bulking agent from urethral diverticulum and periurethral cyst. Radiologists should consider differential diagnosis of a bulking agent, especially when distinguishing characteristics described here are present to prevent incorrect diagnosis and ultimately unnecessary surgical intervention.

Image quality and diagnostic accuracy of complex-averaged high b value images in diffusion-weighted MRI of prostate cancer.

PURPOSE: To evaluate the impact of complex-averaging on image quality (IQ) and diagnostic accuracy of acquired and calculated high b value (aHBV, cHBV) images in diffusion-weighted prostate MRI. MATERIALS AND METHODS: This retrospective study included 84 patients who underwent multiparametric prostate MRI at 3 Tesla without endorectal coil. DWIs were acquired at three different b values which included two lower b values (b = 50,900 s/mm2) and one higher b value (aHBV at 2000 s/mm2). The acquired data were postprocessed to generate two different types of trace-weighted images-using conventional magnitude-averaging and complex-averaging. Using lower b values (b = 50,900 s/mm2) from both conventional and complex-averaged image sets, cHBV images (b = 2000 s/mm2) and ADC maps were derived. All image sets were reviewed by two radiologists in different reading sessions to assess image quality and PIRADS. The diagnostic accuracy of different image sets for the detection of prostate lesions was performed by correlating PIRADS and Gleason scores. RESULTS: Complex-averaging did not impact ADC values of the prostate lesions compared to magnitude-averaging (P = 0.08). Complex-averaging improved image quality of acquired high b value and calculated high b value images (P < 0.0001). Complex-averaging also improved the level of confidence (LOC) of the acquired high b value for both readers (P < 0.0001, P < 0.05), but only for reader A in calculated high b value (P < 0.0001). The image quality of calculated high b value images was not significantly different than acquired high b value images. The dataset combining complex-averaging and calculated high b value provided the highest diagnostic accuracy (but not statistically significant) for detection of the significant prostate lesion compared to the magnitude-averaged acquired high b value (79.55% vs. 72.73%; P = 0.317). The mean acquisition time for b = 2000 s/mm2 sequence (aHBV) was 6 min 30 s (± 1 min 16 s) out of a total of 28 min 31 s (± 4 min 26 s) for the entire mp-MRI protocol (approximately 25% of total scan time). CONCLUSION: Complex-averaging provides better image quality and level of confidence without significant impact on ADC values and diagnostic accuracy for detection of the significant prostate lesions . The calculated high b value images are also comparable to (and can substitute) the acquired high b value images which can help in reducing the imaging time.

CT-Visualized Colonic Mural Stratification Independently Predicts the Need for Medical or Surgical Rescue Therapy in Hospitalized Ulcerative Colitis Patients.

BACKGROUND: Severe ulcerative colitis is associated with significant morbidity. Multidetector computed tomography (MDCT) scans are frequently obtained upon hospital admission, but the ability of radiographic findings to predict steroid failure is unknown. AIM: To identify MDCT features predictive of inpatient rescue in hospitalized UC. METHODS: Patients hospitalized with UC who underwent a CT scan within 48 h of hospitalization were retrospectively identified. Radiologists blinded to the outcome prospectively evaluated CT scans for the presence of bowel wall thickening, stranding, and hyperenhancement as well as mural stratification, mesenteric hyperemia, and proximal dilation. Logistic regression adjusting for potential confounders was used to test the independent association between radiographic findings and need for rescue therapy. RESULTS: The study cohort included 74 patients. The mean age of the group was 45 years, and two-thirds (66%) were male. Twenty-eight (38%) patients required either inpatient medical rescue or colectomy. The mean number of positive radiographic findings was 4.4 (range 2-6) with a higher median number of findings in those who required rescue therapy (5 vs. 4, p = 0.03). Mural stratification was significantly more common among those who required rescue therapy (92% vs. 49%, p = 0.001). No other radiographic findings were independently associated with inpatient rescue. On multivariable analysis, mural stratification (OR 14.9, 95% CI 2.76-80.2) and number of positive findings (OR 2.10, 95% CI 1.06-4.16) remained independently predictive of the need for rescue therapy. CONCLUSIONS: Mural stratification was highly predictive of steroid refractoriness and need for medical or surgical rescue therapy in hospitalized UC.

Comparative accuracy of qualitative and quantitative 18F-FDG PET/CT analysis in detection of lymph node metastasis from anal cancer.

PURPOSE: To compare the diagnostic performance of qualitative and quantitative 18F-FDG PET/CT in detection of regional and distant lymph node metastasis in patients with anal cancer. METHODS: Between 2004 and 2017, 28 patients with anal cancer who had staging PET/CT and pathological assessment of suspicious lymph nodes were included. For qualitative analysis, positive lymph nodes were defined as uptake visually higher than the liver reference uptake. For quantitative study, lymph nodes were contoured to determine maximum standard uptake value (SUVmax) and metabolic tumor volume (MTV). Receiver operating characteristic (ROC) curves were plotted to extract the optimal cut-offs and area under the curve (AUC) of SUVmax, lesion to background (L/B) ratio, short axis diameter (SAD), and MTV of lymph nodes. Histopathologic analysis was a reference standard. RESULTS: A total of 28 lymph nodes (24 inguinal, 2 external iliac, 1 internal iliac, and 1 paraaortic nodes) in 28 patients on PET/CT were included. With the qualitative visual analysis, 19 patients were categorized as positive for nodal metastasis with sensitivity, specificity, and accuracy of 85%, 75%, and 82%. The optimal SUVmax and L/B ratio cut-offs were 2.6 and 1.0 with both sensitivity and specificity of 95% and 75% (AUC of SUVmax = 0.893, AUC of L/B ratio = 0.912). Using the best cut-off of 1.6 cm for SAD and 3.65 cm3 for MTV, both sensitivity and specificity were 80% and 100% (AUC of SAD = 0.950, AUC of MTV = 0.931). CONCLUSIONS: SUVmax optimization may be helpful in enhancing the diagnostic accuracy of 18F-FDG PET/CT in nodal staging patients with anal cancer.

Survey on practice patterns in imaging utilization in patients with Crohn's disease.

PURPOSE: To perform a survey-based assessment of imaging practice preferences in Crohn's disease (CD). METHODS: An internet-based questionnaire was sent to physicians involved in CD care. The questionnaire addressed the experience, practice patterns, choice of modality, and recent trends in imaging utilization. RESULTS: The response rate was 7.57% (122/1598) with 43.8% of respondents involved in care of CD for ≥10 years. CT was mostly preferred by ED physicians, internists and primary care physicians, while MRI by gastroenterologists and pediatricians. Practitioners from non-teaching facilities had higher preference for CT (CT:42% andMR:27%), compared to teaching/academic hospitals (MR:45% and CT: 40%) (p = 0.06). MR was preferred by pediatric practitioners compared to physicians serving older age group of patients (>16 yrs) (p = 0.01). CT was preferred by physicians taking care of <50 patients/year (CT:37, MR:27, No preference = 19) and MR preferred by physicians serving ≥50 patients/year (CT:12, MR:21, No preference:3)(p = 0.02). CT/CT enterography was the most widely used exam (93.3%) and preferred modality for evaluation of acute CD exacerbation (87.7%), followed by assessment for new symptoms (73.7%) and extra-intestinal manifestations (61.3%). MR/MR enterography (58%) was more preferred for asymptomatic CD patients for disease surveillance. Nearly 80% of respondents reported a change in imaging preferences, 46.5% respondents indicating growing preference for MRI while 33.3% reported increasing preference for CT. 29.6% physicians reported a patient preference for MRI over CT (13%) with the most common factor for choice of MRI being fear of harmful effects of radiation (60.2%). CONCLUSION: Physician practices reported continued preference for CT in evaluation of patients with CD, particularly for evaluation of acute exacerbation, new symptoms or extra-intestinal manifestations. Physician providers with large practice volume, younger patient population and GI sub-specialty expertise report growing MRI utilization.

Dual-Source Dual-Energy CT in Detection and Characterization of Urinary Stones in Patients With Large Body Habitus: Observations in a Large Cohort.

OBJECTIVE: The objective of our study was to investigate the impact of large body habitus on dual-energy CT (DECT) image quality and stone characterization. MATERIALS AND METHODS: We retrospectively included 105 consecutive patients with large body habitus (> 90 kg) who underwent stone protocol DECT between 2015 and 2017. The evaluation of DECT datasets was performed for image quality assessment based on European Guidelines on Quality Criteria for Computed Tomography and for determination of stone composition (i.e., uric acid vs non-uric acid). Correlation between DECT characterization and crystallography results was performed when available. The cohort was divided into two groups on the basis of body weight (≤ 104 kg and > 104 kg), and comparisons were made for image quality and stone characterization. RESULTS: One hundred ninety-seven urinary tract calculi (size: mean ± SD, 5.7 ± 5.3 mm; range, 1.4-56 mm) were detected in 73% (79/108) of examinations in 105 patients (weight: mean ± SD, 104.0 ± 12.7 kg; range, 91-163 kg). The overall mean image quality score of blended images and color maps was 3.7 and 3.9, respectively, and the effective dual-energy FOV limitation did not hamper stone characterization. The diagnostic acceptability scores of blended images and color maps were slightly lower in patients weighing > 104 kg than in patients ≤ 104 kg (mean scores [highest score, 4 points]: blended images, 3.62 vs 3.82 [p = 0.0314]; color maps, 3.75 vs 3.98 [p = 0.0034]), but the scores were within acceptable range. Stone characterization as uric acid versus non-uric acid was achieved in 80% (158/197) of calculi (size: mean ± SD, 6.4 ± 5.7 mm; range, 1.6-56 mm), and DECT stone characterization was (95.6%) accurate with reference to crystallography. Twenty percent (39/197) of calculi could not be characterized on DECT, and these calculi were significantly smaller in size (size: mean ± SD, 2.8 ± 1.4 mm; range, 1.4-8.2 mm; p < 0.001) than those that could be characterized. The mean size of uncharacterized calculi was slightly larger in patients weighing > 104 kg (3.3 ± 1.6 mm) than in those weighing ≤ 104 kg (2.2 ± 0.6 mm). CONCLUSION: In patients with large body habitus, dual-source DECT provides acceptable image quality and allows characterization of almost all clinically significant calculi.

False-Negative Low Tube Voltage Coronary CT Angiography: High Intravascular Attenuation at Coronary CT Angiography Can Mask Calcified Plaques.

PURPOSE: To determine the impact of low tube voltage coronary CT angiography on detection of subclinical atherosclerosis. MATERIALS AND METHODS: Retrospective sampling of an emergency department coronary CT angiography registry was performed. All patients in the registry underwent a noncontrast coronary artery calcium (CAC) scoring scan at 120 kV before coronary CT angiography. The study sample (n = 264) constituted patients with subclinical atherosclerosis (Coronary Artery Disease Reporting and Data System™ [CAD-RADS] 1 or 2) randomly mixed one-to-one with patients without atherosclerosis (CAD-RADS 0). The patients with coronary CT angiography performed at 70-90 kV were considered the low tube voltage group (n = 159) and patients with coronary CT angiography performed at 100-120 kV were considered the standard tube voltage group (n = 105). The number of coronary plaques and overall CAD-RADS classification (per patient) were evaluated twice: initially, by reading coronary CT angiography alone, and then, by coronary CT angiography in combination with a CAC scan. Considering the combined reading (CT angiography plus CAC scan) as the reference standard, the performance of coronary CT angiography alone was assessed for plaque detection and appropriate CAD-RADS (per patient) classification. The comparisons were made between the low tube voltage and standard tube voltage groups by using a Fisher exact test and χ2 test for proportions and a Mann-Whitney test and Kruskal-Wallis test for means. RESULTS: In total, 455 plaques were identified in 118 patients (70 of 159 patients in the low tube voltage group; 48 of 105 in the standard tube voltage group). When reading coronary CT angiographic images alone, 97 of 455 (21%) plaques were missed that led to an incorrect CAD-RADS classification in 16 of 264 (6%) studies (interpreted as CAD-RADS 0 instead of CAD-RADS 1 or 2). Missed plaques were significantly more frequent in the low tube voltage group versus the standard tube voltage group (41% [85 of 206] vs 5% [12 of 249], respectively; P < .001). Incorrect CAD-RADS classification was also seen more commonly in the low tube voltage group (8.8% [14 of 159] vs 2% [two of 105]; P = .01), typically at low plaque burden (median CAC score, 1; range, 1-4). Calcified plaques that appeared isodense to luminal contrast material attenuation were seen more frequently in the low tube voltage group compared with the standard tube voltage group (20% [32 of 159] vs 7.6% [eight of 105], respectively; P = .005). CONCLUSION: Coronary artery plaques may be missed at low tube voltage coronary CT angiographic examination performed without a concomitant CAC scan.© RSNA, 2019Supplemental material is available for this article.See also the commentary by Truong in this issue.

Contrast- vs. non-contrast enhanced MR data sets for characterization of perianal fistulas.

PURPOSE: To evaluate the diagnostic efficacy between pre- and post-contrast MRI sequences in perianal fistulas using intra-operative findings as the gold standard. MATERIALS AND METHODS: Retrospective analysis of 50 patients with a history of perianal fistula and MRI performed between January 2006 and January 2018 was performed. The inclusion criteria were patients who underwent MRI prior to surgery and had a detailed surgical report available. Pre- and post-contrast MR data sets were evaluated by two radiologists at two-week-intervals, assessed fistula type, internal/external opening, presence of abscess/secondary tracts, and confidence scores. The area under the curve (AUC) was used for comparison the diagnostic ability. The sensitivity and specificity were compared using the McNemar's test. RESULTS: The confidence scores in detecting perianal fistulas were significantly higher in the post-contrast MR data set (p < 0.003). The post-contrast MR data set had similar ability to classify perianal fistulas as combined T2-DWI and isolated T2 data sets in 49/50 cases. For internal/external opening, the post-contrast MR, combined T2-DWI, and isolated T2 data sets had 100% concordance with intra-operative reports. For perianal abscess, there was no significant difference in sensitivity or AUC value between the isolated T2 or combined T2-DWI data sets and post-contrast MR data set (p > 0.05). All MR data sets correctly identified secondary tracts in all 50 cases. CONCLUSIONS: Although contrast-enhanced MR studies can improve a radiologist's confidence, non-contrast MR studies had similar diagnostic efficacy in identifying perianal fistulas and their complications. Therefore, a non-contrast study may suffice in selected patients such as those with renal impairment.

Can MR imaging be useful in differentiating low rectal cancer from anal cancer?

PURPOSE: To evaluate the role of pelvic MR imaging in differentiating between low rectal and anal cancers using the pathological results as the gold standard. MATERIALS AND METHODS: In this study, retrospective analysis of 100 patients with a history of low rectal (n = 50) or anal (n = 50) cancers who underwent staging pelvic MR imaging before treatment was performed. The following parameters were analyzed: distance from the anal verge to the tumor, percentage of tumor above puborectalis muscle, tumor size, T2W signal intensity, sphincter/levator muscles invasion, organ invasion, and MRI diagnosis. Multivariable logistic regression was performed to determine factors associated with low rectal and anal cancers. Distances from the anal verge to the tumor were compared using receiver-operating characteristic (ROC) curves. RESULTS: From the ROC curves, the cut-off value for the distance from the anal verge to the tumor in differentiating between low rectal and anal cancers was 2.1 cm and the area under the ROC curve was 0.90 (95% CI 0.84-0.97). Multivariate logistic regression revealed three significant factors in differentiating between low rectal and anal cancers, including T2 mixed hyper- and hyposignal intensity (OR 66.00, 95% CI 4.66-934.81), distance cut-off value (OR 34.72, 95% CI 5.73-210.27), and absence of sphincter invasion (OR 18.75, 95% CI 1.91-183.96), with sensitivity, specificity, PPV, and NPV of 98%, 88%, 89%, and 97%, respectively, and diagnostic accuracy increased from 79% (reader 1) and 82% (reader 2) to 93%. CONCLUSION: MR imaging can be useful to differentiating between low rectal and anal cancers which benefits staging and treatment planning.

Orthopedic metallic hardware in routine abdomino-pelvic CT scans: occurrence and clinical significance.

PURPOSE: To study the occurrence of orthopedic metallic hardware in routine abdomen/pelvic computed tomography (CT) scans and their impact on image quality (IQ) and diagnostic evaluation. MATERIAL AND METHODS: In this retrospective single institution study, we analyzed 3500 consecutive abdomen/pelvis CT scans for occurrence of orthopedic metallic hardware. In the cohort of patients with metallic hardware detected on CT scans, subjective and objective IQ analysis was performed to estimate diagnostic acceptability (DA, 4-point scale), subjective noise (SN, 3-point scale), presence of artifacts (PA, 4-point scale) and objective noise. The clinical significance of metallic hardware was determined by evaluating the impact of artifacts on radiological diagnosis according to the clinical indication and disease type. RESULTS: Orthopedic metallic hardware was encountered in 4.97% of abdomino-pelvic CT scans (n = 174/3500), and artifacts related to the hardware in the region of clinical interest were identified in 82% (n = 144/174) of scans. The overall mean DA was 2.66 (n = 174), and it was severely limited (score < 2) in 32% of cases particularly affecting patients with bilateral hip implants (92.6%, n = 25/27). The artifacts due to hardware significantly limited diagnostic evaluation in 58.6% of cases (PA score ≥ 3), and the image noise was unacceptable in 71% of cases (SN score > 2) in the region of clinical interest. CONCLUSION: Orthopedic metallic hardware is encountered in nearly 5% of abdomino-pelvic CT scans and causes significant image degradation limiting diagnostic evaluation in the region of clinical interest.

Rapid kVp switching dual-energy CT in the assessment of urolithiasis in patients with large body habitus: preliminary observations on image quality and stone characterization.

PURPOSE: The purpose of this study was to investigate the image quality (IQ) considerations of rapid kVp switching dual-energy CT (rsDECT) in the assessment of urolithiasis in patients with large body habitus and to evaluate whether it allows stone characterization. MATERIALS AND METHODS: In this IRB-approved, HIPAA compliant retrospective study, 93 consecutive patients (M/F = 72/21, mean age 56.9 years, range 23-83 years) with large body habitus (> 90 kg/198 lbs) who underwent dual-energy (DE) stone protocol CT on a rapid kVp switching DECT scanner between January 2013 and December 2016 were included. Scan acquisition protocol included an initial unenhanced single-energy CT (SECT) scan of KUB followed by targeted DECT in the region of stones. Two readers evaluated both CT data sets (axial 5 mm 120 kVp/140 kVp QC/70 keV monoenergetic, material density water/iodine images and coronal/sagittal 3 mm images) for the assessment of image quality (Scores: 1-4) and characterization of stone composition (reference standard: crystallography). RESULTS: One hundred and five CT examinations were performed in 93 patients (mean body weight 105.12 ± 13.53 kg, range 91-154 kg), and a total of 321 urinary tract calculi (mean size-4.8 ± 3.2 mm, range 1.2-22 mm) were detected. Both SECT and targeted monoenergetic images were of acceptable image quality (mean IQ: 3.77 and 3.83, kappa 0.79 and 0.87 respectively). Material density water and iodine images had lower IQ scores (mean IQ: 2.97 and 3.09 respectively) with image quality deterioration due to severe photon starvation/streak artifacts in 20% (21/105) and 17% (18/105) scans, respectively. Characterization of stone composition into uric acid/non-uric acid stones was achieved in 93.14% (299/321) of calculi (mean size: 4.99 ± 3.3 mm, range 1.2-22 mm), while 7% (22/321) stones could not be characterized (mean size 3.03 ± 1.16 mm, range 1.6-6.4 mm) (p < 0.001). Most common reason for non-characterization was image quality deterioration of the material density iodine images due to severe photon starvation artifacts. On multivariate regression, stone size and patient weight were predictors of stone composition determination on DECT (p < 0.05). The transverse diameter had a weak negative correlation with stone composition determination, but it was not statistically significant. Stone characterization into uric acid vs. non-uric acid stones was accurate in 95% (n = 38/40) of stones in comparison with crystallography. CONCLUSION: In patients with large body habitus, rsDECT allowed characterization of most calculi (93%) despite image quality deterioration due to photon starvation/streak artifacts in up to 20% of material density images. Stone size and patient weight were predictors of stone composition determination on DECT, and small calculi in very large patients may not be characterized.