Liver Imaging Reporting and Data System: Discordance Between Computed Tomography and Gadoxetate-Enhanced Magnetic Resonance Imaging for Detection of Hepatocellular Carcinoma Major Features.

PURPOSE: The goal of this study was to compare agreement between computed tomography (CT) and magnetic resonance imaging (MRI) in the evaluation of the major Liver Imaging Reporting and Data System (LI-RADS) features used in assessment of hepatocellular carcinoma: arterial phase hyperenhancement (APHE), portal venous phase washout (WO), capsule appearance (capsule), and largest diameter (diameter). METHODS: Patients with liver protocol CT and gadoxetate-enhanced MRI within 1 month of each other and at least 1 discrete untreated liver lesion were included. Two readers independently reviewed hepatic arterial phase and portal venous phase of each lesion on both CT and MRI, presented at random. The APHE, WO, capsule, and diameter were assessed for each lesion on CT and MRI. The LI-RADS category was assigned based on the recorded major features. Interobserver agreements between the readers for both imaging modalities and for each of the major features were assessed using κ statistics. Agreement between CT and MRI for each reader and for each feature was assessed using κ statistics. Agreement was interpreted based on κ as follows: 0.20 or less, slight agreement; 0.21 to 0.40, fair agreement; 0.41 to 0.60, moderate agreement; 0.61 to 0.80, substantial agreement; and 0.81 to 1.00, almost perfect agreement. Intraclass correlation coefficient was used to assess concordance of diameter measurements. RESULTS: There were 42 patients (mean age, 62.2 ± 7.0 years; 33 men [78.6%]) with 50 lesions. On CT, the interobserver agreement between the readers was almost perfect for APHE (κ = 0.85), WO (κ = 0.83), and capsule (κ = 0.86). On MRI, the interobserver agreement between the readers was almost perfect for APHE (κ = 0.86) and WO (κ = 0.83) and moderate for capsule (κ = 0.59). Intraclass correlation coefficient for diameter measurement was 0.99 for CT and 0.98 for MRI. For reader 1, the agreement between CT and MRI was fair for APHE (κ = 0.39) and capsule (κ = 0.26) and moderate for WO (κ = 0.49). For reader 2, the agreement between CT and MRI was moderate for APHE (κ = 0.43) and capsule (κ = 0.43) and fair (κ = 0.38) for WO. Agreement between readers for final LI-RADS category was substantial for CT (κ = 0.79) and moderate for MRI (κ = 0.60). Agreement for final LI-RADS categories between MRI and CT was fair for both reader 1 (κ = 0.33) and reader 2 (κ = 0.39). CONCLUSIONS: Interobserver agreement for the major LI-RADS features varies from moderate to almost perfect, for both CT and MRI. However, the agreement between CT and MRI for each of the major LI-RADS features is poor, ranging from fair to moderate. This poor agreement contributes to substantial differences between final LI-RADS category assigned on CT versus MRI.

Transient arterial phase respiratory motion-related artifact in MR imaging of the liver: an analysis of four different gadolinium-based contrast agents.

PURPOSE: The purpose was to compare hepatic arterial phase (HAP) respiratory motion artifact (RMA) between gadoxetate, gadobutrol, gadopentetate, and gadobenate. MATERIALS/METHODS: Two hundred cases of each gadolinium agent were included. RMA was assigned using 5-point Likert scale (1=no motion, 5=extreme motion) on precontrast and HAP. RMA increase (increase ≥1 on HAP from precontrast) was the outcome in logistic regression. RESULTS: Odds of RMA increase for gadoxetate were 5.5 (P<.001), 3.6 (P=.034), and 9.5 (P<.001) times higher than gadobutrol, gadopentetate, and gadobenate, respectively. Gadolinium volume and dose were not independent predictors of RMA increase. CONCLUSION: Gadoxetate has increased odds of RMA compared with other gadolinium agents; tight contrast bolus is not a contributor.

Pancreatic cysts: What imaging characteristics are associated with development of pancreatic ductal adenocarcinoma?

PURPOSE: To assess relationship between pancreatic cysts (PC) and pancreatic ductal adenocarcinoma (PDAC) and to compare imaging features of PC in subjects who develop PDAC and those who do not. MATERIAL AND METHODS: This case-control IRB-approved HIPAA-compliant study included patients with PDAC (cases) and lung cancer (controls), diagnosed between 1/1/05-1/1/14. The most recent abdominal CT/MR of each patient done >6months prior to cancer diagnosis date was reviewed by radiologist blinded to case/control status. Presence of PC, number and size of largest PC, presence of main pancreatic duct (MPD) dilatation (MPD >3mm) were recorded. Simple PC was defined as lack of calcifications, septations and enhancement. Logistic regression models with binary outcome of PDAC were constructed. RESULTS: There were 88 cases and 273 controls with mean ages of 69.6 years (±10.3) and 69.8 years (±12.0), respectively (p=0.864). PC were present in 21.6% (19/88) cases and in 9.2% (25/273) controls (p=0.002). The OR of PC for development of PDAC was 2.83, adjusting for age, sex and race (p=0.001). Mean PC size was 14.8mm (±8.7) in cases and 7.6mm (±8.0) in controls (p=0.007). PC were solitary in 6 (31.6%) of 19 cases and 21 (84.0%) of 25 controls (p=0.001). There was no significant difference in proportions of simple cysts or MPD dilatation between cases and controls. Multiple PC had 8.2 times increased odds of PDAC compared with solitary PC, adjusting for cyst size (p=0.007). CONCLUSION: Multiple PC are associated with 8.2 times higher odds of PDAC compared with solitary PC.

Improving diagnosis of atraumatic splenic lesions, part II: benign neoplasms/nonneoplastic mass-like lesions.

Focal atraumatic splenic lesions often pose a diagnostic challenge on cross-sectional imaging. They can be categorized based on etiology as nonneoplastic, benign neoplastic (discussed in Part II), and malignant neoplastic lesions or on prevalence as common, uncommon, and rare lesions. Familiarity with pertinent clinical parameters, etiology, pathology, prevalence and ancillary features such as splenomegaly, concomitant hepatic involvement, and extrasplenic findings, in addition to knowledge of imaging spectra of the lesions, can improve diagnostic confidence. Consideration of these factors together can arm the radiologist with the necessary tools to render a more confident diagnosis and, thus, better aid management.

Hollow organ abdominal ischemia, part II: clinical features, etiology, imaging findings and management.

Acute hollow organ ischemia commonly presents with acute pain prompting radiologic evaluation and almost always requires urgent treatment. Despite different risk factors and anatomic differences, ischemia is commonly due to low flow states but can also be due to arterial and venous occlusion. Radiologic diagnosis is critical as many present with nonspecific symptoms. Contrast-enhanced computed tomography (CT) is the modality of choice. Magnetic resonance imaging (MRI) is preferred in suspected appendicitis in pregnant patients and is superior in biliary necrosis. This article provides a pictorial review of the CT/MRI features of hollow abdominal organ ischemia while highlighting key clinical features, pathogenesis, and management.

Improving diagnosis of atraumatic splenic lesions, part I: nonneoplastic lesions.

Focal atraumatic splenic lesions often pose a diagnostic challenge on cross-sectional imaging. They can be categorized based on etiology as nonneoplastic (reviewed in Part I), benign neoplastic, and malignant neoplastic lesions. Lesions can also be characterized based on prevalence as common, uncommon, and rare. Familiarity with pertinent clinical parameters, etiology, pathology, prevalence, and ancillary features such as splenomegaly, concomitant hepatic involvement, and extrasplenic findings, in addition to knowledge of imaging spectra of these lesions, can improve diagnostic confidence. Since the nonneoplastic lesions are usually easily recognized, it is critical that the radiologist identifies them avoiding unnecessary work up.

Solid organ abdominal ischemia, part I: clinical features, etiology, imaging findings, and management.

Solid organ abdominal ischemia commonly presents with acute pain prompting radiologic evaluation and often requires urgent treatment. Despite different risk factors and anatomic differences, most solid organ ischemia is due to arterial or venous occlusion and, less frequently, a low-flow state. Radiologic diagnosis is critical, as clinical presentations are often nonspecific. Contrast-enhanced computed tomography (CT) is the modality of choice (except in adnexal torsion) with magnetic resonance imaging (MRI) useful in equivocal cases or follow-up of ischemic disease. This article will provide a pictorial review of the CT and MRI features of solid abdominal organ ischemia while highlighting key clinical features, etiology, and management.

Improving diagnosis of atraumatic splenic lesions, Part III: malignant lesions.

Focal atraumatic splenic lesions often pose a diagnostic challenge on cross-sectional imaging. They can be categorized based on etiology, as nonneoplastic, benign neoplastic, and malignant neoplastic (discussed in Part III) lesions, or on prevalence, as common, uncommon, and rare lesions. Familiarity with pertinent clinical parameters, etiology, pathology, prevalence, and ancillary features such as splenomegaly, concomitant hepatic involvement, and extrasplenic findings, in addition to knowledge of imaging spectra of the lesions, can improve diagnostic confidence. Consideration of these factors together can arm the radiologist with the necessary tools to render a more confident diagnosis and thus better aid management.

Patients 65 years and older with incidental pancreatic cysts: Is there a relationship between all-cause mortality and imaging follow-up?

PURPOSE: To assess the relationship between imaging follow-up and all-cause mortality in subjects ≥65 years with and without incidental pancreatic cysts (IPC). METHODS AND MATERIALS: Patients ≥65 years with abdominal CT/MR 11/1/01-11/1/11 were included. IPC group included subjects with IPC on CT/MR report; No-IPC group was 3:1 frequency-matched on age decade, imaging modality and year of initial study from the pool without reported IPC. Demographics, date of last encounter, date of death, Charlson scores within 3 months before initial CT/MR and number of abdominal CTs and MRs performed after initial study were recorded. Logistic regression models with binary outcomes of death and having post-index imaging were constructed. Models were adjusted for age, race, sex, Charlson score and follow-up time. Subgroups were created based on interactions between variables. RESULTS: There were 1320 subjects in IPC group and 3805 in No-IPC group, with mean ages 79.1 (±8.0) and 78.8 (±8.0) years, respectively (p=0.293), and median follow-up times of 3.1 (IQR 0.74-5.26) and 3.0 (0.36-5.23) years, respectively (p=0.009). Adjusted odds ratios of post-index imaging for IPC were 2.18 (p<0.001) in subgroup<84years and follow-up <4years, 3.37 (p<0.001) in subgroup <84 years and follow-up ≥4 years, and 1.20 (p=0.201) in subgroup ≥84 years. Number of follow-up CTs and MRs was not independently associated with decreased odds of death in any subgroup. CONCLUSION: Older subjects with IPC are more likely to undergo imaging follow-up compared to subjects without IPC, yet increasing number of follow-up studies does not decrease the odds of death.

Diagnosis of acute cholecystitis: why do patients get multiple studies?

The aim of this study is to establish factors affecting total number of imaging studies performed for acute cholecystitis (AC) prior to surgery. The study included subjects with cholecystectomy and pathologic diagnosis of AC 1/1/05-1/1/14 and imaging studies (computed tomography (CT), ultrasound (US), and/or cholescintigraphy) within 7 days of surgery. The subjects were separated into groups based on modality of the first study. For each subject, report of the first study was reviewed for report's confidence in diagnosis of AC (scored 1-5 on Likert scale: 5 = definitely AC, 1 = definitely no AC), recommendation of additional study, clinical history concerning for AC (history of right upper quadrant pain, cholelithiasis, and/or "rule out AC"). There were 219, 339, and 38 subjects in CT, US, and cholescintigraphy groups, respectively, with mean confidence scores of 3.7 (± 1.2), 3.7 (± 1.1), and 4.7 (± 0.9), respectively (p < 0.001). Prior to surgery, only one study was performed in 21.9 % (48/219) of CT group, 70.2 % (238/339) of US group, and 71.1 % (27/38) of cholescintigraphy group (p < 0.0001). Compared to the US group, the odds of undergoing additional study were 11.8 times higher (p < 0.001) in CT group and 1.7 times higher (p = 0.229) in cholescintigraphy group, adjusting for age, sex, time interval between first study and the surgery, confidence score, recommendation of follow-up study, and clinical history concerning for AC. Patients with AC and CT as the first study are more likely to undergo additional imaging studies prior to surgery as compared to US or cholescintigraphy.

T1-hyperintense renal lesions: can high signal predict lack of enhancement?

OBJECTIVE: To establish highly specific criteria for predicting non-enhancement in T1-hyperintense non-fat-containing (T1-high) renal lesions using unenhanced fat-suppressed T1-weighted (T1-FS) images. MATERIALS AND METHODS: This IRB-approved, HIPAA-compliant, retrospective study included T1-high renal lesions found between 7/1/2012 and 7/1/2014. The largest lesion diameter and heterogeneity, mean signal intensity of lesion, and adjacent renal cortex were recorded from T1-FS images. The presence/absence of lesion enhancement was determined from subtraction images. T1 signal ratio (T1-SR) was calculated as (mean SI of lesion)/(mean SI of cortex). Logistic regression with binary outcome of the presence or absence of lesion enhancement was performed. Cut-off T1-SR to maximize specificity was established from receiver operator curve analysis. RESULTS: There were 101 patients (58 [57.4%] male) with non-enhancing lesions and 80 patients (51 [63.8%] male) with enhancing lesions, mean ages 64.0 ± 13.3 and 62.1 ± 13.8 years, respectively. Median sizes were 11 mm (IQR 8-16) and 20.5 mm (IQR 15-29) for non-enhancing and enhancing lesions, respectively (p < 0.0001). 19/101 (18.8%) of non-enhancing and 56/80 (70.0%) of enhancing lesions were heterogeneous (p < 0.0001). T1-SR was 1.77 ± 0.6 and 1.25 ± 0.42 for non-enhancing and enhancing lesions, respectively (p < 0.0001). For each increase of 0.5 in T1-SR, odds ratio for non-enhancement was 3.3 (95% CI 1.85-5.79), adjusted for lesion size and heterogeneity. T1-SR alone had area under the curve of 0.88 (95% CI 0.78-10.89) for non-enhancement. T1-SR ≥ 2.15 had positive likelihood ratio of 9.5 for non-enhancement. CONCLUSION: Signal ratio of lesion to cortex ≥ 2.15 on unenhanced T1-weighted images is a highly specific predictor for non-enhancement.

Traumatic and non-traumatic adrenal emergencies.

Multiple traumatic and non-traumatic adrenal emergencies are occasionally encountered during the cross-sectional imaging of emergency department patients. Traumatic adrenal hematomas are markers of severe polytrauma, and can be easily overlooked due to multiple concomitant injuries. Patients with non-traumatic adrenal emergencies usually present to an emergency department with a non-specific clinical picture. The detection and management of adrenal emergencies is based on cross-sectional imaging. Adrenal hemorrhage, adrenal infection, or rupture of adrenal neoplasm require immediate detection to avoid dire consequences. More often however, adrenal emergencies are detected incidentally in patients being investigated for non-specific acute abdominal pain. A high index of suspicion is required for the establishment of timely diagnosis and to avert potentially life-threatening complications. We describe cross-sectional imaging findings in patients with traumatic and non-traumatic adrenal hemorrhage, adrenal infarctions, adrenal infections, and complications of adrenal masses.

Accuracy of prostate measurements on MRI with and without an endorectal coil.

PURPOSE: To assess accuracy of prostate measurements with and without endorectal coil (ERC). MATERIALS AND METHODS: Anteroposterior (AP), transverse (TX) and craniocaudal (CC) measurements were recorded from 49 prostate magnetic resonance images (MRIs) done both with and without ERC. Prostate weight was calculated as follows: AP*TX*CC*π/6. Prostate dimensions and weight were obtained from radical prostatectomy pathology report. RESULTS: After ERC placement, AP decreased by 0.71 cm [95% confidence interval (CI) 0.80-0.61], TX and CC increased by 0.26 cm (95% CI 0.18-0.33) and 0.25 cm (95% CI 0.16-0.35), respectively. Agreement between weight on pathology and MR was excellent: intraclass correlation coefficient (ICC) without ERC=0.96, ICC with ERC=0.90. CONCLUSION: Although ERC distorts measurements and despite a tendency to underestimate the prostate weight, absolute agreement between prostate weight on pathology and MRI is excellent, both with and without ERC.

Incidental pancreatic cystic lesions: is there a relationship with the development of pancreatic adenocarcinoma and all-cause mortality?

PURPOSE: To establish the effect of incidental pancreatic cysts found by using computed tomographic (CT) and magnetic resonance (MR) imaging on the incidence of pancreatic ductal adenocarcinoma and overall mortality in patients from an inner-city urban U.S. tertiary care medical center. MATERIALS AND METHODS: Institutional review board granted approval for the study and waived the informed consent requirement. The study population comprised cyst and no-cyst cohorts drawn from all adults who underwent abdominal CT and/or MR November 1, 2001, to November 1, 2011. Cyst cohort included patients whose CT or MR imaging showed incidental pancreatic cysts; no-cyst cohort was three-to-one frequency matched by age decade, imaging modality, and year of initial study from the pool without reported incidental pancreatic cysts. Patients with pancreatic cancer diagnosed within 5 years before initial CT or MR were excluded. Demographics, study location (outpatient, inpatient, or emergency department), dates of pancreatic adenocarcinoma and death, and modified Charlson scores within 3 months before initial CT or MR examination were extracted from the hospital database. Cox hazard models were constructed; incident pancreatic adenocarcinoma and mortality were outcome events. Adenocarcinomas diagnosed 6 months or longer after initial CT or MR examination were considered incident. RESULTS: There were 2034 patients in cyst cohort (1326 women [65.2%]) and 6018 in no-cyst cohort (3,563 [59.2%] women); respective mean ages were 69.9 years ± 15.1(standard deviation) and 69.3 years ± 15.2, respectively (P = .129). The relationship between mortality and incidental pancreatic cysts varied by age: hazard ratios were 1.40 (95% confidence interval [ CI confidence interval ]: 1.13, 1.73) for patients younger than 65 years and 0.97 (95% CI confidence interval : 0.88, 1.07), adjusted for sex, race, imaging modality, study location, and modified Charlson scores. Incidental pancreatic cysts had a hazard ratio of 3.0 (95% CI confidence interval : 1.32, 6.89) for adenocarcinoma, adjusted for age, sex, and race. CONCLUSION: Incidental pancreatic cysts found by using CT or MR imaging are associated with increased mortality for patients younger than 65 years and an overall increased risk of pancreatic adenocarcinoma.

Beyond ultrasound: CT and MRI of ectopic pregnancy.

OBJECTIVE: Although ultrasound is the primary modality used in the diagnosis of ectopic pregnancy, various forms of this condition and their complications may occasionally be further evaluated with MRI or may be incidentally detected on CT or MRI when an alternative diagnosis is suspected. CONCLUSION: Various types of ectopic pregnancy have characteristic imaging features. Radiologists should be familiar with these features and should always consider the possibility of ectopic pregnancy in the setting of hemoperitoneum or a pelvic mass in a woman of child-bearing age. Familiarity with the typical CT and MRI appearances of various forms of ectopic pregnancy facilitates prompt and accurate diagnosis and treatment.

Effect of visceral obesity on minimally invasive partial nephrectomy.

OBJECTIVE: To assess the relationship between visceral obesity and perioperative parameters in patients undergoing laparoscopic or robotic-assisted partial nephrectomy. METHODS: We retrospectively reviewed the medical records of 118 patients who underwent minimally invasive partial nephrectomy. On preoperative imaging, perinephric, visceral, and subcutaneous fat were measured. Higher estimated blood loss, complications, and warm ischemia time were used as surrogates of increased operation difficulty. We examined the association between the 3 groups of patients (ie low, medium, and high fat) with demographic and clinical characteristics. Multivariate analysis was performed to determine whether various measurements of obesity adversely affected surgical outcomes and complexity. RESULTS: No statistically significant differences were found between perioperative parameters and either perinephric, visceral, or subcutaneous fat. There was no association between changes in renal function and different fat groups. Multivariate analysis for estimated blood loss, complication rates, and warm ischemia time adjusted for age, race, sex, nephrometry score, Charlson comorbidities score, and other fat types, failed to demonstrate any significant differences. Increasing perinephric fat content was associated with higher visceral (P <.0005), but not subcutaneous fat (P = .55). Hypertension was associated with perinephric (P = .02) and visceral (P = .04), but not subcutaneous obesity (P = .08). Neither Charlson comorbidity nor American Society of Anesthesiologists scores showed any significant association with different fat types. CONCLUSION: Individual patterns of obesity, namely subcutaneous, visceral, and perinephric, do not increase surgical complexity for minimally invasive partial nephrectomy by experienced surgeons. Furthermore, this operation can be performed safely with comparable complications and outcomes in moderately obese patients without compromising renal function.

MR imaging of renal collecting system with gadoxetate disodium: feasibility for MR urography.

PURPOSE: To determine the feasibility of using gadoxetate disodium for MR urography. MATERIALS AND METHODS: We retrospectively reviewed 50 consecutive gadoxetate disodium-enhanced abdominal MRI examinations meeting inclusion criteria. For each examination, 30 min postcontrast hepatobiliary phase sequences were reviewed to assess bilateral collecting system segments, including upper pole, interpolar, and lower pole calyces; renal pelvis; and proximal one-third of ureter. Each segment was assessed for degree of opacification (none, <50%, ≥50%, complete) and susceptibility artifact (none, partial thin rim, thick/complete rim, total obscuration). Opacification and susceptibility scores were also calculated for each examination. RESULTS: The 50 reviewed examinations were performed on 46 patients (26 women, 20 men; mean age, 57 years) and included a total of 1000 segments. Of these, 808 (80.8%) were opacified completely, 103 (10.3%) were opacified ≥50%, 39 (3.9%) were opacified <50%, and 50 (5.0%) were not opacified. Of 1000 segments, no susceptibility artifact was present in 822 (82.2%), while a partial thin rim was present in 113 (11.3%), a thick/complete rim in 64 (6.4%) and total obscuration in 1 (0.1%). CONCLUSION: Gadoxetate disodium contrast produced a high degree of opacification of the proximal urinary collecting system with low incidence of susceptibility artifact; therefore, it is a feasible contrast agent for MR urography.

Gallbladder torsion resulting in gangrenous cholecystitis within a parastomal hernia: findings on unenhanced CT.

Gallbladder torsion is a rare cause of acute gangrenous cholecystitis; its occurrence within an abdominal hernia has not been previously reported. We present such a case occurring within a parastomal hernia and imaged with unenhanced CT.