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Background & Aims Liver ultrasound (US) is usually used in the clinical setting for the diagnosis and follow-up of patients with nonalcoholic fatty liver disease (NAFLD). However, no large study has carefully assessed its performance using a semiquantitative ultrasonographic scoring system in overweight/obese patients, in comparison to magnetic resonance spectroscopy (1H-MRS) and histology. Methods We recruited 146 patients and performed: a liver US using a 5-parameter scoring system, a liver 1H-MRS to quantify liver fat content, and a liver biopsy to assess histology. All measurements were repeated in a subgroup of patients (n = 62) after 18 months of follow-up. Results The performance of liver US (parenchymal echo alone) was rather modest, and significantly worse than 1H-MRS (AUROC: 0.82 [0.69–0.94] vs. 0.96 [0.90–1.00]; P = 0.04). However, the AUROC improved when different echographic parameters were taken into account (AUROC: 0.89 [0.83–0.96], P = 0.15 against 1H-MRS). Optimum sensitivity for liver US was achieved at a liver fat content ≥12.5%, suggesting that below this threshold, liver US is less sensitive. Liver 1H-MRS showed a high accuracy for the diagnosis of NAFLD, and correlated strongly with histological steatosis (r = 0.73, P

Carcinoid tumors are a rare biologically heterogeneous group of neuroendocrine tumors with a spectrum ranging from benign indolent to aggressive metastatic tumors. They belong to the category of amine precursor uptake and decarboxylase tumors, or apudomas. The most common sites for primary locations are the gastrointestinal and respiratory tracts; however, any organ can be involved. The clinical presentation depends on location, aggressiveness, production of biologically active amines and peptides, paraneoplastic syndromes, and tendency for metastasis. Their reported age-adjusted incidence has increased in recent years, partly due to improved detection at radiologic imaging and endoscopy. Not a ll neuroendocrine cell tumors are carcinoids. Numerous systems have been proposed regarding their nomenclature and classification. Cross-sectional and functional imaging plays an important role in diagnosis, lesion characterization, and staging. Awareness of nomenclature, classification, common sites of involvement, and imaging presentation are pivotal for making the diagnosis. Knowledge of the diverse clinical, pathologic, and radiologic spectrum of carcinoid tumors involving various organs of the body is important for diagnosis and patient management. ©RSNA, 2017.

Adrenal collision tumors (ACTs) refer to coexistence of two adjacent, but histologically distinct neoplasms involving the adrenal gland without histologic admixture at interface. ACTs include adenoma with myelolipoma, adenoma with metastases, hemangioma with adenoma, and adrenocortical carcinoma with myelolipoma. In addition, hemorrhage into a pre-existing adrenal mass can mimic an ACT, and it is important to differentiate these two pathologies. Accurate characterization of ACTs is difficult, but critical, for correct staging of patients with malignancies and to guide percutaneous biopsy. Magnetic resonance imaging (MRI) and multidetector computed tomography imaging techniques may depict different tumor components separately; however, biopsy may be required in selected patients for confirmation. [18F]Fluorodeoxyglucose-positron emission tomography (PET) shows increased uptake in the malignant component of ACTs, and guides percutaneous biopsy. Even in patients requiring percutaneous biopsy for a definite diagnosis, imaging findings can help in guiding the appropriate component to be biopsied. Knowledge of imaging findings of different ACTs and their mimics on MRI, computed tomography, and PET help in optimal patient management.

Hemangiomas are a radiologist's dream lesions because they allow a confident diagnosis most of the time. However, within the abdomen, hemangiomas may occur in such atypical locations and can have such unusual features that they cause significant diagnostic dilemma and may end up being excised surgically. The literature is replete with isolated case reports of atypical hemangiomas in the abdominal cavity, and, to our knowledge, so far, there is no comprehensive review. We present, in this article, a pictorial review of a gamut of uncommon hemangiomas and hemangiomatosis syndromes. Knowledge of these rare types can help in limiting diagnostic errors and increase the confidence of radiologists, thus avoiding unnecessary surgeries.

OBJECTIVE. For most patients with morbid obesity, bariatric surgery is the only effective method to achieve sustainable weight loss. Small bowel obstruction (SBO) after bariatric surgery is a major complication that affects postoperative course and management. Knowledge of the types of and imaging findings for SBO is essential to prompt diagnosis.CONCLUSION. We discuss different types of SBO and a taxonomic schemata of bowel obstruction (ABC classification) and present a review of imaging findings that facilitates optimal patient management.

OBJECTIVE. A broad spectrum of benign renal neoplasms in adults shows characteristic ontogeny, histology, and tumor biology. Benign renal tumors are classified into renal cell tumors, metanephric tumors, mesenchymal tumors, and mixed epithelial and mesenchymal tumors. Select benign tumors show characteristic anatomic distribution and imaging features. However, because of overlapping of findings between benign and malignant renal tumors, histologic evaluation may be required to establish a definitive diagnosis. Accurate preoperative characterization facilitates optimal patient management.CONCLUSION. We attempt to provide a comprehensive, contemporary review of benign renal neoplasms that occur in adults, focusing on cross-sectional imaging characteristics.

Twenty asymptomatic volunteers underwent helical computed tomographic (CT) cholangiography 10-12 hours after ingesting iopanoic acid. Three observers assessed the images for the extent of bile duct visualization and image quality. The common bile duct and common hepatic duct were adequately visualized in 19 (95%) subjects. Helical CT cholangiography with oral cholecystographic contrast material is feasible and deserves further clinical studies.

The aim of this article is to present pictorially the spectrum of appearances of the appendix and appendicitis on CT. The images presented were selected from the database of our hospitals. The various appearances of the normal appendix on CT are shown. Appendicitis can be divided into four categories on the basis of CT findings. Examples of each category are shown.

There is an increasing incidence of both intra- and extra-thoracic manifestations of tuberculosis, in part due to the AIDS epidemic. Isolated tubercular involvement of the solid abdominal viscera is relatively unusual. Cross-sectional imaging with ultrasound, multidetector computed tomography (CT), and magnetic resonance imaging (MRI) plays an important role in the diagnosis and post treatment follow-up of tuberculosis. Specific imaging features of tuberculosis are frequently related to caseous necrosis, which is the hallmark of this disease. However, depending on the type of solid organ involvement, tubercular lesions can mimic a variety of neoplastic and nonneoplastic conditions. Often, cross-sectional imaging alone is insufficient in reaching a conclusive diagnosis, and image-guided tissue sampling is needed. In this article, we review the pathology and cross-sectional imaging features of tubercular involvement of solid abdominopelvic organs with a special emphasis on appropriate differential diagnoses.

With the increasing use of multidetector computed tomography and dynamic magnetic resonance imaging in evaluation of liver pathologies, a variety of vascular shunts are detected in the liver. These shunts can be related to tumors or they can be nonneoplastic. Identification of these shunts can help in diagnosing an underlying condition. We classify and describe a wide spectrum of intrahepatic vascular shunts with their key imaging features. After reviewing this article, the reader should have improved ability to detect and characterize intrahepatic vascular shunts, which will help in diagnosing an underlying condition and facilitate optimal patient care.

The purpose of this article is to discuss radiation dose during CT-guided interventions and to explain how radiologists can modify technical factors to minimize radiation doses. Scanner-displayed indexes of radiation exposure that are available during the procedure will be defined to increase awareness about CT radiation dose reduction during interventional procedures.CT-guided fluoroscopic procedures are safe and effective methods of directed intervention; however, the increasing use of medical radiation is an important consideration. The appropriate use of imaging with an acceptable risk must be considered in every case. During CT-guided interventions, scanner parameters that can be used as a guide for effective dose management, including the CT dose index and dose-length product, are readily displayed. These parameters can be adjusted by modifying the longitudinal scan length, number of scans, and tube current-exposure time product (milliampere × second [mAs]). A team approach to radiation dose reduction will work the best.

Miscellaneous tumour-like ovarian lesions are histobiologically diverse, and are often mistaken for the more common ovarian cancers, leading to aggressive management. Knowledge of characteristic clinical, laboratory and imaging findings of these select non-neoplastic ovarian entities allows correct diagnoses and permits optimal management.

Aberrant internal carotid arteries presenting as pharyngeal masses are described in the literature. Eight patients were evaluated by CT, angiography or MRI. Our studies indicated that the phyaryngeal pseudo masses were due to aberrant carotid vessels. Unlike the previous reports, in tour of our eight cases both common and internal carotid arteries were the cause of the suspected mass. Contrast-enhanced CT studies consistently demonstrated the abnormalities. MRI may be done if patients have a contraindication to intravenous iodinated contrast administration.

Benign hepatic neoplasms constitute a heterogeneous group of neoplasms with characteristic histology and variable tumor biology. Based on the cell of origin, benign hepatic neoplasms are classified into epithelial, nonepithelial, and miscellaneous categories according to the 2000 World Health Organization classification system. Benign hepatic neoplasms demonstrate a wide spectrum of imaging findings that reflect the histomorphologic changes. Some neoplasms show pathognomic imaging findings that permit accurate characterization and optimal management.

A case of pseudomyxoma peritonei with increased radionuclide uptake in the abdomen is described. The uptake of the radionuclide was confined to the omentum as confirmed by the CT study of the abdomen and pelvis. The mechanism of uptake and differential diagnosis are discussed.

To determine the sensitivity, specificity, and accuracy of helical computed tomographic (CT) angiography in the detection of transjugular intrahepatic portosystemic shunt (TIPS) stenoses or occlusions.Thirty-seven patients underwent 50 helical CT angiographic examinations and, within 2 weeks of each examination, portography with measurement of the portosystemic pressure gradient. Helical CT angiograms were independently interpreted by three radiologists who were blinded to the results of portography. Results of helical CT angiography and portography were compared. Sensitivity and specificity of helical CT angiography were separately calculated for the demonstration of morphologic abnormalities and the determination of their hemodynamic significance.Of the 50 portograms, 31 (62%) demonstrated morphologic TIPS abnormalities, 24 (77%) with and seven (23%) without elevated portosystemic pressure gradients. Helical CT angiograms correctly demonstrated 30 (97%) of the 31 morphologic abnormalities and allowed correct diagnosis of 22 (92%) of the 24 hemodynamically significant abnormalities. Nineteen (38%) portograms were normal; helical CT angiograms correctly demonstrated the absence of abnormality in 17 (90%) of these cases. Sensitivity and specificity of helical CT angiography for all morphologic abnormalities were 97% and 89%, respectively, and, for hemodynamically significant abnormalities, 92% and 77%.Helical CT angiography holds promise as a screening modality for the detection of TIPS stenoses or occlusions.

Shunt dysfunction due to draining hepatic vein and/or stent stenosis is a common long-term complication of transjugular intrahepatic portosystemic shunts (TIPS). Currently, Doppler sonography is the preferred modality for routine screening of TIPS for the detection of these complications. However, this method is time-consuming, highly operator-dependent, and difficult to perform because of the anatomic attributes of the cirrhotic liver. The use of helical CT angiography (HCTA) for imaging TIPS has been recently described. HCTA of TIPS is performed after a rapid i.v. injection of a bolus of low osmolality contrast medium, followed by helical data acquisition of the region of the shunt using thin sections. The data are then reprocessed a overlapping intervals and various reformations are obtained. Preliminary reports show the sensitivity and specificity of the helical CT angiography to be comparable with Doppler sonography.

Recent advances in radiology have greatly increased the ability to make highly accurate diagnosis. Biopsy of many commonly seen lesions is no longer performed as the radiological findings are pathognomonic. This gives rise to the concept of ‘virtual biopsy’, a term coined on the lines of other imaging techniques such as virtual colonoscopy. Virtual biopsy is not a new imaging technique but a new concept which refers to the use of existing imaging modalities to evaluate the morphological features of tumors and arriving at a non-invasive diagnosis with a high degree of confidence obviating the need for true biopsy. Elements of virtual biopsy have already been incorporated into some evidence-based guidelines, and it is expected that with further technological advancements, an increasing number of tumors may be diagnosed and managed accordingly. A wider acceptance of virtual biopsy could further reduce the need for invasive biopsies and its attendant costs and risks. In this review article, we use index cases to further emphasize this concept.

Purpose: Use of GAFCHROMIC® XR‐QA film to estimate entrance skin dose and skin dose measurements resulting from computed tomography‐guided procedures such as tumor ablation cyst aspiration and needle biopsies. Materials and Methods: Small pieces of GAFCHROMIC® XR‐QA each measuring approximately 1 × 6 cm2 were exposed to different measured radiation doses using a conventional x‐ray tube. The beam energy used was 117 kVp with a measured a HVL of 5.15 mm Al. An additional 1.85 mm Al were added to better approximate the beam characteristics of a computed tomography x‐ray beam of 120 kVp and a HVL of 7 mm Al. After 24 hours post‐exposure the films were scanned with a commercially available reflective‐type scanner. The mean pixel value measured for each film was used to calculate a net pixel value. The film calibration curve was generated by plotting the radiation dose as a function of net pixel value and then performing a curve fit. For each of seven computed‐tomography procedures selected a GAFCHROMIC® XR‐QA film strip measuring approximately 1 × 30 cm2 was positioned on the patient's skin parallel to the direction of table movement during the entirety of the procedure. The GAFCHROMIC® XR‐QA film strips were scanned and a dose profile generated.Results: The GAFCHROMIC® XR‐QA film skin dose measurements for all the patients so far investigated had a maximum dose ranging from 8–267 mGy with an average skin dose between 0.7–125 mGy. Conclusion: GAFCHROMIC® XR‐QA film has the potential for performing quick and reliable radiation skin dose measurements for patients undergoing computed tomography guided procedures. Skin dose profiles may be used to determine maximum or peak skin dose to provide feedback to physicians on their radiation management techniques and to optimize the CT scan parameters in order to minimize patient dose while maintaining diagnostic quality imaging.

The parapharyngeal space with its complex anatomy is of great clinical importance. Because of its location deep within the neck, this space is difficult to examine by ordinary methods but can be well demonstrated in the axial transverse plane by computed tomography (CT). This paper is primarily concerned with the normal anatomy of the parapharyngeal space as seen on CT but also includes examples of representative pathological conditions.

A retrospective computed tomography evaluation of proved low-attenuation splenic lesions in nontraumatic cases was done. Computed tomography was able to distinguish cystic from solid lesions. Although computed tomography examination is sensitive in the detection of low-attenuation lesions, the computed tomography findings alone are not helpful in differentiation of different low-attenuation lesions. Associated computed tomography findings in other organs and clinical findings are more helpful than the size, shape, and computed tomography attenuation of the lesions. Splenic lesions may be the only metastatic manifestation in some cancer patients. A thin needle aspiration may be done to document the nature of the pathologic lesion in problematic cases.

A case of perinephric abscess with renal cell carcinoma is presented. Hematuria is uncommon in cases of perinephric abscess. When hematuria is present in a patient with perinephric abscess further evaluation is necessary to rule out an associated malignant process.

The incidence of renal fascial thickening in pancreatic inflammatory disease was evaluated by computed tomography. A total of 71 cases including chemical, acute complicated, and acute and chronic uncomplicated pancreatitis were retrospectively evaluated for thickening of the renal fascia. Renal fascial thickening is demonstrated in the majority of patients with complicated and uncomplicated pancreatitis. It is not demonstrated in cases of chemical pancreatitis. Renal fascial thickening is nonspecific and seen with inflammatory, malignant, and traumatic processes, but it is a valuable adjunctive sign of pancreatic inflammatory disease.

A comparison of hepatic computed tomography (CT) before and after administering intravenous contrast material was performed 85 times on 81 patients suspected of having hepatic mass lesions. Both pre- and postcontrast computed tomography were sensitive and specific in over 88% of cases, with no statistical difference in accuracy between the techniques. However, postcontrast scans were generally preferred because of increased diagnostic confidence and improved characterization of associated abnormalities. The recent advent of rapid sequential scanning after intravenous administration of a large volume of contrast material seems to further improve diagnostic confidence. When high-resolution CT equipment is used, postcontrast CT alone is the preferred method for CT evaluation of patients with suspected liver lesions.

In the identification of discrete and conglomerate retroperitoneal lymph node masses, MRI and CT performed equally well. No specific MRI characteristics were identified.

The classic radiographic appearance of pulmonary aspergilloma is a solid, round, often mobile intracavitary mass. We describe an unusual “cavity-incavity” appearance seen on conventional roentgenograms and computed tomography studies in two patients with confirmed pulmonary aspergilloma. We are not aware of any previous report describing such appearance based on literature search.

History A 32-year-old man presented with bilateral progressive paresthesia and numbness over a two-year period following a motor vehicle accident. He reported the recent onset of urinary incontinence. On examination, decrease in pain and sensation to touch and pinprick in both lower extremities, more marked on the left side, was elicited. The findings of electromyographic studies were consistent with involvement of the posterior primary rami at the T10-11 level. Lateral roentgenograms of the thoracic spine showed a triangular bony density projecting into the spinal canal (open arrow) at the site of T10-11 (Fig 1). Low-dose metrizamide myelography with computed tomography (CT) was accomplished. The CT scans will be demonstrated subsequently. An operative procedure was performed. Diagnosis Ossification of the ligamentum flavum at T10 through T12 causing myelopathy. A CT scan using low doses of metrizamide shows ossification of the ligamentum flavum (LF) (open arrows), compressing the spinal cord at T10-11

In Reply.— I agree with the comments of Drs Sarwar and Naseem. Unfortunately, MRI is done in patients with no previous radiographic studies, such as CT. Magnetic resonance imaging has, in my opinion, limited use in the evaluation of calcifications as they appear as low-intensity signals. Plain roentgenograms may demonstrate the abnormality better than MRI studies. Computed tomography due to the axial display of the ligamentum flavum localizes the calcifications well. Dr Olson's comments are well taken. Ligamentous ossification involving the ligamentum flavum or posterior longitudinal ligament contributes to spinal stenosis. Trauma, vascular lesions, and a tendency to ossify ligaments, such as in diffuse idiopathic skeletal hyperostosis (Forestier's disease), are some of the causes of ossification. Ossification may be an associated radiological abnormality, as in patients with thoracic posterior longitudinal ligament ossification. 1