Prospective evaluation of the prevalence of non-alcoholic fatty liver disease and steatohepatitis in a large middle-aged US cohort.

BACKGROUND & AIMS: Large prospective studies to establish the prevalence of non-alcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH), are lacking. We prospectively assessed the prevalence and severity of NAFLD/NASH in a cohort of asymptomatic middle-aged Americans attending a colonoscopy class at a gastroenterology clinic. METHODS: Screening for NAFLD was performed using magnetic resonance (MR)-based LiverMultiScan® proton density fat fraction (LMS-PDFF). MR exams also included corrected T1 and elastography for liver stiffness measurement (LSM). FibroScan® was also used to measure LSM. Participants with predetermined abnormal imaging parameters were offered a liver biopsy. Biopsies were read in a blinded fashion with results based on the consensus by 2 expert pathologists. The prevalence of NAFLD was determined by PDFF ≥5% or by histological diagnosis of NAFLD (if biopsy data were available). The prevalence of NASH was defined by biopsy. RESULTS: Of 835 participants, 664 met the inclusion and exclusion criteria. The mean age was 56 ± 6.4 years, 50% were male, the mean BMI was 30.48 ± 5.46 kg/m2, and 52% were obese. The prevalence of NAFLD was 38% (95% CI 34-41%) and the prevalence of NASH was 14% (95% CI 12-17%). While no patient had cirrhosis on biopsy, significant fibrosis (F ≥2) was present in 5.9% (95% CI 4-8%) and bridging fibrosis in 1.6% (95% CI 1-3%). In a multivariable analysis, factors associated with the presence of NASH were race, obesity, and diabetes. CONCLUSION: Using state-of-the-art liver imaging modalities and reference biopsy, this study establishes an overall prevalence of NAFLD of 38% and NASH by biopsy of 14% in this cohort of asymptomatic middle-aged US adults. LAY SUMMARY: There are no prospective studies to determine how common is nonalcoholic steatohepatitis (NASH), the severe form of non-alcoholic fatty liver disease (NAFLD). In a large number of asymptomatic middle-aged Americans, we used a combination of state-of-the-art liver imaging methods and liver biopsy to prospectively determine the prevalence of NAFLD and NASH. NAFLD was diagnosed in 38%, NASH in 14%, and significant liver fibrosis in 6% of asymptomatic middle-aged Americans.

The double corpus luteum: A novel sonographic sign of heterotopic pregnancy.

Heterotopic pregnancy is a rare and highly morbid condition with simultaneous intrauterine and extra-uterine pregnancies. The early diagnosis of heterotopic pregnancy is difficult, owing to rarity of the condition and nonspecific clinical and laboratory findings. This case report introduces the "double corpus luteum" sign, a new sonographic and magnetic resonance imaging sign which is easily detectable and should raise the index of suspicion for heterotopic pregnancy. We present a surgically confirmed spontaneous heterotopic and angular pregnancy in a young woman without risk factors or assisted reproductive therapy to illustrate the utility of this novel sign.

Incidental Renal Lesions on Lumbar Spine MRI: Who Needs Follow-Up?

OBJECTIVE: Incidentally discovered renal lesions on lumbar spine MRI are a common occurrence. Many follow-up recommendations are generated by radiologists encountering renal lesions to help characterize the finding as a benign cyst or a more complex, potentially malignant lesion. We hypothesized that analysis of T2-weighted imaging features of incidentally discovered renal lesions could reliably distinguish complex renal lesions from simple cysts. MATERIALS AND METHODS: Two independent readers retrospectively evaluated 149 renal lesions identified on lumbar spine MRI examinations. Presence or absence of a complex renal lesion was determined using T2-weighted imaging only. Using dedicated renal cross-sectional imaging examinations as the reference standard, statistical analysis was performed to determine the accuracy of lumbar spine MRI in predicting a complex and potentially neoplastic renal lesion. RESULTS: Of 149 renal lesions, 115 were simple cysts, and 34 were complex renal lesions (20 Bosniak II cysts, nine renal cell carcinomas, three Bosniak IIF cysts, and two angiomyolipomas). Lumbar spine MRI readers identified 72 lesions as simple cysts and 77 lesions as complex renal lesions. Reader sensitivity for detection of a complex renal lesion on lumbar spine MRI was 94% (95% CI, 80-99%); specificity, 63% (95% CI, 53-72%); positive predictive value, 43% (95% CI, 37-49%); and negative predictive value, 97% (95% CI, 90-99%). Readers correctly identified all neoplastic and potentially neoplastic lesions (≥ Bosniak IIF). Interreader agreement was excellent (κ = 0.84). CONCLUSION: Follow-up imaging may not be required in all cases of incidentally discovered renal lesions on lumbar spine MRI. Analysis of T2-weighted imaging alone appears to reliably rule out neoplastic and potentially neoplastic complex renal lesions.

Postoperative CT of the Midfacial Skeleton After Trauma: Review of Normal Appearances and Common Complications.

OBJECTIVE: The objective of this article is to describe the CT appearance of the midfacial skeleton after surgical repair of posttraumatic Le Fort, nasoorbitoethmoidal (NOE), and frontal sinus fractures. Several of the more commonly encountered complications will also be described. CONCLUSION: Surgery after midfacial trauma is aimed at restoring both form and function. Knowledge of the principal tenets of Le Fort, NOE, and frontal sinus fracture repair is vital for radiologists to accurately assess the adequacy of treatment on postoperative CT and provide meaningful reports for the surgeon.

Postoperative CT of the Orbital Skeleton After Trauma: Review of Normal Appearances and Common Complications.

OBJECTIVE: The purpose of this article is to describe both the expected and unexpected imaging features of posttraumatic defects of the orbital skeleton after surgical repair. CONCLUSION: The goal of surgery is to restore the preinjury orbital anatomy to improve function and prevent enophthalmos. Radiologists need to be cognizant of the more frequently encountered operative procedures used for orbital fracture repair, the desired goals of treatment, and common complications. This will permit accurate interpretation of postoperative CT and provide surgeons with clinically useful results.

Effect of Low-Osmolar Intravenous Contrast on Renal Length.

OBJECTIVE: The purpose was to study the effect of low-osmolar nonionic contrast on renal length. MATERIAL AND METHODS: This study included 56 patients (4-phase renal computed tomography [CT] and 4-phase CT urogram [CTU], 19 patients each; split-phase CTU, 18 patients). Three radiologists created the best off-axis plane and renal lengths measured on a postprocessing workstation. Two-way analysis of variance with Bonferroni corrections was performed along with single-sample t tests. RESULTS: Four-phase renal CT and CTU average differences from unenhanced phases were 0.30/0.16 mm (corticomedullary), 0.88/1.33 mm (nephrographic), and 2.17/2.22 mm (delayed). The nephrographic and delayed phases were significantly different from their unenhanced phase (P < 0.01). Nonsignificant differences between the corticomedullary phase and the unenhanced phase were observed (P = 0.217, 4-phase renal CT; P = 0.232, 4-phase CTU). The split-phase CTU average difference in the enhanced phase was 1.36 mm (P < 0.001). CONCLUSION: Renal length increases 1 to 2 mm with low-osmolar nonionic contrast.

Multiplanar Reformations in the Measurement of Renal Length on CT: Is It Plain Which Plane to Use?

OBJECTIVE: The objective of this study was to determine the accuracy of renal measurement on CT in multiple imaging planes. MATERIALS AND METHODS: In this study, three board-certified radiologists retrospectively measured 110 kidneys on CT in 55 consecutive patients. Five measurement methods were used: axial, coronal single image, coronal multiimage, sagittal single image, and sagittal multiimage. The coronal database was sent to a postprocessing workstation, and each radiologist performed a maximum renal measurement using a best off-axis plane that was our reference standard. An ANOVA test with repeated measures and posthoc Bonferroni corrected t tests were performed. RESULTS: The mean differences (± standard error) compared with the reference standard method were as follows: axial, 7.7 ± 0.7 mm; coronal single image, 13.1 ± 1.4 mm; coronal multiimage, 6.4 ± 0.8 mm; sagittal single image, 6.4 ± 0.6 mm; and sagittal multiimage, 2.8 ± 0.3 mm. The reference standard measurement was larger (p < 0.001), whereas the coronal single-image measurement (p ≤ 0.006) was smaller than all other methods. The sagittal multiimage (p ≤ 0.005) was statistically significantly different from all other methods. There were no statistically significant differences among the axial, coronal multiimage, and sagittal single-image methods (p ≥ 0.088). CONCLUSION: The single-image coronal method is the least accurate, with an error of approximately 13 mm. The axial, multiimage coronal, and single-image sagittal methods underestimate renal size by approximately 6-8 mm. Multiimage sagittal is the most accurate method for measuring kidneys with an error of approximately 3 mm.

Surgical management of retrorectal lesions: what the radiologist needs to know.

OBJECTIVE. The purpose of this article is to highlight the most salient imaging features of retrorectal masses with regard to surgical planning, preoperative biopsy, and identification of nonneoplastic mimickers of malignancy. CONCLUSION. Retrorectal tumors are associated with high morbidity. CT and MRI aid in preoperative planning because surgical resection is the treatment of choice for both benign and malignant entities. Radiologists need to understand the operative techniques currently used for retrorectal tumors because the first attempt at excision is the best chance for complete resection and optimal outcome.

Postoperative imaging of the orbital contents.

Ophthalmologists perform a wide array of interventions on the orbital contents. The surgical treatment of glaucoma, cataracts, retinal detachment, and ocular trauma or malignancy results in alteration of the standard anatomy, which is often readily evident at radiologic examinations. The ability to accurately recognize the various imaging manifestations after orbital surgery is critical for radiologists to avoid misdiagnosis. Of particular importance is familiarity with the numerous types of implanted devices, such as glaucoma drainage devices, orbital implants, and eyelid weights. Although knowledge of patients' surgical history is helpful, this information is often not available at the time of interpretation. Fortunately, there are characteristic posttreatment findings that enable diagnosis. The imaging features of the most commonly performed ophthalmologic procedures are highlighted, with emphasis on computed tomography and magnetic resonance (MR) imaging, because they are currently the primary modalities involved in evaluating the orbits. Glaucoma drainage devices and orbital implants after enucleation are two of the more pertinent implanted devices because their composition has substantially evolved over the past 2 decades, which affects their imaging appearance. Some devices, such as the Baerveldt Glaucoma Implant and platinum-weighted eyelid implants, may distort radiologic images. The MR imaging safety profiles of numerous implanted devices are also reported.

Review of Commonly Used Serum Tumor Markers and Their Relevance for Image Interpretation.

Serum tumor markers are firmly entrenched as one of the primary tools in an oncologist's armamentarium. They can be implemented in a broad range of applications from diagnostic assistance, assessing prognosis, or guiding therapeutic decisions. However, tumor markers also have limitations, which significantly impact how they should be used. Radiologists should be familiar with the following most prevalent tumor markers, which will all be discussed here: prostate-specific antigen (prostate), carcinoembryonic antigen (colon), α-fetoprotein (hepatocellular and testicular), carbohydrate antigen 19.9 (pancreas), cancer antigen 125 (ovarian), human chorionic gonadotropin/lactic dehydrogenase (testicular), and chromogranin A (neuroendocrine). This knowledge should avoid needless intervention, enhance image interpretation, and ultimately provide optimal patient care.

Mimickers of neoplasm on abdominal and pelvic CT.

PURPOSE: The radiologist can encounter benign significant imaging findings on computed tomography that can be incorrectly interpreted as neoplasm. The authors review several benign findings and demonstrate several methods to differentiate these findings from more sinister pathology. CONCLUSION: It is imperative for the radiologist to be cognizant of and how to correctly identify mimickers of pathology so that unnecessary interventions and surgeries are avoided.

Can a T2 hyperintense rim sign differentiate uterine leiomyomas from other solid adnexal masses?

PURPOSE: To investigate the incidence of high T2 signal rims surrounding leiomyomas, evaluate if a particular T2-weighted sequence is more effective in depicting this rim, and determine if this sign is useful in differentiating pedunculated leiomyomas from other solid adnexal masses. MATERIALS AND METHODS: In this retrospective study, two radiologists evaluated 233 T2 dark pelvic masses (223 uterine leiomyomas and 10 ovarian fibromas) in 60 women (mean age 47) on Magnetic resonance imaging for the presence of a high signal rim. Three different T2-weighted sequences were reviewed independently for uterine leiomyomas: half-Fourier acquisition single-shot turbo spin echo (HASTE), SPACE, and T2 with fat saturation (T2 FS). Only T2 FS images were available for 10 fibromas. A consensus review was conducted for discrepant cases. Statistical analyses were performed using Fisher's exact test, kappa test, and ANOVA RESULTS: For 223 uterine leiomyomas, 23% (95% CI 17.8-28.9%) demonstrated a high T2 signal rim sign on T2 FS compared with 4.9% (95% CI 2.6-8.9%) for HASTE and 6.7% (95% CI 3.9-11.1%) for SPACE. The difference between the number of positive rims on T2 FS relative-HASTE and SPACE was statistically significant (p < 0.001). For ovarian fibromas, 40% (95% CI 16.9-68.8%) were classified positive for a rim sign. CONCLUSION: A high T2 signal rim sign was present for up to 23% of uterine leiomyomas and the T2 FS sequence detected this rim sign most frequently. Up to 40% of ovarian fibromas can also have a T2 rim sign and, therefore, a solid adnexal mass with a T2 rim sign cannot be assumed to represent a pedunculated leiomyoma.

Gadoxetic acid: pearls and pitfalls.

Gadoxetic acid is a hepatocyte-specific magnetic resonance imaging contrast agent with the ability to detect and characterize focal liver lesions and provide structural and functional information about the hepatobiliary system. Knowledge of the pharmacokinetics of gadoxetic acid is paramount to understanding imaging protocol and lesion appearance and facilitates identification and avoidance of undesired effects with use of this intravenous contrast agent. This article reviews the utility of gadoxetic acid in liver and biliary imaging, with emphasis on the hepatobiliary phase.

Role of imaging for patients with colorectal hepatic metastases: what the radiologist needs to know.

Surgical resection of colorectal metastatic disease has increased as surgeons have adopted a more aggressive ideology. Current exclusion criteria are patients for whom a negative resection margin is not feasible or a future liver remnant (FLR) of greater than 20% is not achievable. The goal of preoperative imaging is to identify the number and distribution of liver metastases, in addition to establishing their relation to relevant intrahepatic structures. FLR can be calculated utilizing cross-sectional imaging to select out patients at risk for hepatic dysfunction after resection. MRI, specifically with gadoxetic acid contrast, is currently the preferred modality for assessment of hepatic involvement for patients with newly diagnosed colorectal cancer, to include those who have undergone neoadjuvant chemotherapy. Employment of liver-directed therapies has recently expanded and they may provide an alternative to hepatectomy in order to obtain locoregional control in poor surgical candidates or convert patients with initially unresectable disease into surgical candidates.

CT evaluation of the upper urinary tract in adults younger than 50 years with asymptomatic microscopic hematuria: is IV contrast enhancement needed?

OBJECTIVE: The purpose of this study is to compare CT urography (CTU) with unenhanced CT in the evaluation of upper urinary tracts in adults younger than 50 years with asymptomatic microscopic hematuria. MATERIALS AND METHODS: In this study, 1516 CTU examinations were reviewed in adults younger than 50 years. Inclusion criteria were no significant prior urologic disease and asymptomatic microscopic hematuria with at least one urinalysis with greater than or equal to 3 RBCs/high-power field and less than or equal to 50 RBCs/high-power field. Upper urinary tract findings on CTU were classified as malignancy-related or non-malignancy-related hematuria and incidental non-hematuria-related findings. A blinded radiologist reviewed the unenhanced images, recording upper urinary tract findings and recommendations for further contrast-enhanced imaging. The modified Wald equation at a 95% CI, the "Rule of Threes" equation, and binomial distribution were used for malignancy-related findings. RESULTS: Four hundred forty-five examinations in 442 patients met inclusion criteria. CTU reports showed zero malignancy-related hematuria findings, 64 non-malignancy-related hematuria findings (62 renal calculi and two others), and 138 incidental non-hematuria-related findings. Unenhanced CT interpretation had a sensitivity of 100% (64/64) and a specificity of 89.2% (337/378). The theoretic risk of an upper urinary tract malignancy is 0-1.1%. CONCLUSION: CTU added no additional diagnostic benefit versus unenhanced CT in evaluating the upper urinary tracts of adults younger than 50 years with asymptomatic microscopic hematuria. Using only unenhanced CT can reduce radiation and minimize contrast agent-associated risk, with a less than 1.0% risk of missing upper urinary tract hematuria-related malignancy.

Computed tomography imaging manifestations of commonly used materials in posttraumatic craniofacial repair.

An expansive array of materials exists within the armamentarium of craniofacial surgeons. For patients undergoing repair of posttraumatic injuries, computed tomography is the imaging modality of choice in the postoperative setting. Therefore, radiologists will invariably encounter implants constructed with various materials, depending on the surgeon's preference. The appearance of these materials on computed tomography is broad, ranging from hyperdense to radiolucent. To avoid misdiagnosis, radiologists should be familiar with all of the materials currently in use.

Algorithmic approach to solid adnexal masses and their mimics: utilization of anatomic relationships and imaging features to facilitate diagnosis.

Solid adnexal masses, while less common than their cystic counterparts, may present a challenge for radiologists given the wide range of histologic entities that occur in this region. Pelvic masses, especially when large, can seem overwhelming at first but application of an algorithmic approach allows for more confident assessment. This approach focuses first on the use of anatomic relationships and interactions of various pelvic structures to localize the mass' origin. For instance, the directionality of ureteral displacement can suggest if a mass is intra or extraperitoneal. Then, key discriminating imaging features, such as the presence of fat, hypervascularity, or low T2 signal on magnetic resonance imaging (MRI) can be applied to further narrow the list of diagnostic possibilities. Entities such as leiomyomas, nerve sheath tumors, congenital uterine anomalies, and vascular abnormalities (ovarian torsion or iliac vessel aneurysm) in particular are often accurately characterized with sonography and/or MRI. For solid adnexal masses in which a definitive diagnosis by imaging is not reached, information germane to clinicians regarding further management can still be provided, principally with regard to surgical vs. nonsurgical treatment.

Nonvisualization of the ovaries on pelvic ultrasound: does MRI add anything?

PURPOSE: The purpose of our study is to assess the utility of pelvic magnetic resonance imaging (MRI) in the event that either one or both ovaries are not visualized by pelvic ultrasound. MATERIALS AND METHODS: This HIPAA-compliant retrospective study was approved by our local institutional review board and informed consent waived. 1926 pelvic MRI examinations between March 2007 and December 2011 were reviewed and included if a combined transabdominal and endovaginal pelvic ultrasound had been performed in the preceding 6 months with at least one ovary nonvisualized. Ovaries not visualized on pelvic ultrasound were assumed to be normal and compared with the pelvic MRI findings. MRI findings were categorized as concordant or discordant. Discordant findings were divided into malignant, non-malignant physiologic or non-malignant non-physiologic. The modified Wald, the "rule of thirds", and the binomial distribution probability tests were performed. RESULTS: 255 pelvic ultrasounds met inclusion criteria with 364 ovaries not visualized. 0 malignancies were detected on MRI. 6.9% (25/364) of nonvisualized ovaries had non-malignant discordant findings on MRI: 5.2% (19/364) physiologic, 1.6% (6/364) non-physiologic. Physiologic findings included: 16 functional cysts and 3 hemorrhagic cysts. Non-physiologic findings included: 3 cysts in post-menopausal women, 1 hydrosalpinx, and 2 broad ligament fibroids. The theoretical risk of detecting an ovarian carcinoma on pelvic MRI when an ovary is not visualized on ultrasound ranges from 0 to 1.3%. CONCLUSION: If an ovary is not visualized on pelvic ultrasound, it can be assumed to be without carcinoma and MRI rarely adds additional information.

The "Wet Collar" Sign: A Case of Paraphimosis on CT.

Paraphimosis is a urologic emergency that requires prompt diagnosis to avoid potential morbidity. Diagnosis is made clinically and imaging findings have not been described. We will present the case of an 84-year-old man with a history of metastatic prostate cancer and prior pelvic external beam radiation therapy who presented to the emergency department with urinary retention. A urethral Foley catheter was placed for bladder decompression. He subsequently developed painful penile swelling and was found to have iatrogenic paraphimosis. Retrospective review of his contrast-enhanced CT of the abdomen and pelvis performed while in the emergency department before hospital admission revealed the relatively thickened, hypoattenuating prepuce located proximal to the corona of the glans penis, consistent with the clinical diagnosis. We will examine the imaging findings in this case and propose the novel "wet collar" sign to suggest the diagnosis of paraphimosis on CT.