A wide range of both benign and malignant neoplasms may occur in the liver. Although the characterization of focal hepatic lesions may represent a diagnostic challenge for radiologists, typical imaging findings in these lesions allow a correct diagnosis. The present study is aimed at reviewing imaging findings both in the most frequent benign and malignant focal lesion found in the adult liver.

Keywords: Liver, Neoplasm, Magnetic resonance imaging, Ultrasound, Computed tomography

OBJECTIVE: To establish the role of MRI T2-weighted sequences in the differentiation between simple cysts and hepatic hemangiomas. MATERIALS AND METHODS: A double-blinded, prospective, observational, cross-sectional study evaluated 52 patients with 91 hepatic lesions (34 simple cysts and 57 hemangiomas) submitted to abdominal magnetic resonance imaging. The combined analysis of all sequences was considered as the golden-standard. TSE sequences with long echo trains and b-FFE sequences were subjectively analyzed by two independent observers for differentiating cysts from hemangiomas. The kappa test (κ) was utilized in the analysis of the methods accuracy and inter- and intra-observer agreement (p < 0.05*). RESULTS: Cysts and hemangiomas dimensions ranged respectively between 0.5 and 6.5 cm (mean = 1.89 cm), and 0.8 and 11 cm (mean = 2.62 cm). The analysis of the sequences with long-TE and the golden-standard demonstrated a non-statistically significant agreement (κ: 0.00-0.10). The agreement between the evaluation of the b-FFE sequence and the golden-standard ranged from substantial (κ: 0.62-0.71) to almost perfect (κ: 0.86) for both observers. The inter- and intra-observer agreement for the b-FFE sequence ranged from substantial (κ: 0.62-0.70) to almost perfect (κ: 0.85-0.91). CONCLUSION: T2-weighted images acquired with the b-FFE technique present a high accuracy and reproducibility in the differentiation between cysts and hepatic hemangiomas.

Keywords: Liver, Cyst, Hemangioma, Magnetic resonance imaging

OBJECTIVE: To evaluate the interobserver agreement on non-contrast computed tomography interpretation by a group of experienced abdominal radiologists, for the study of urolithiasis in patients presenting acute flank pain. MATERIALS AND METHODS: Prospective study of 52 patients submitted to non-contrast enhanced helical computed tomography. The images were subsequently analyzed by three independent observers, with the interobserver agreement assessed by means of the kappa (kappa) statistical method. The following parameters were analyzed: a) presence, localization and measurement of ureteral calculi; b) intrarenal calyceal system dilatation; c) perirenal fat heterogeneity; d) ureteral dilatation; e) ureteral wall edema (halo sign). RESULTS: Ureteral calculi were found in 40 of 52 patients (77%). The interobserver agreement was almost perfect as regards identification of ureteral calculi (kappa = 0.89) and ureteral dilatation (kappa = 0.87), substantial for calyceal system dilatation (kappa = 0.77), and moderate for perirenal fat heterogeneity (kappa = 0.55) and ureteral wall edema (kappa = 0.56). CONCLUSION: Non-contrast-enhanced abdominal computed tomography presents high reproducibility in the evaluation of urolithiasis and secondary signs of the calyceal system obstruction.

Keywords: Lithiasis, Ureteral calculi, Flank pain, Computed tomography

OBJECTIVE: To evaluate the qualitative (morphological) and quantitative characteristics of hepatic hemangiomas with magnetic resonance imaging. MATERIAL AND METHODS: Twenty-seven patients with 57 hemangiomas were prospectively studied with magnetic resonance imaging using a system operating at 1.5 T. T1- and T2-weighted spin-echo images were obtained, including heavily T2-weighted images with TE of 160 ms. The morphological characteristics of the hemangiomas were studied and the lesions were classified as typical or atypical. Quantitative parameters (T2 relaxation time, simplified T2 index and lesion/liver signal intensity ratio) were also calculated. The values obtained for typical and atypical hemangiomas were compared as well as for the hemangiomas measuring £ 2.0 cm and > 2.0 cm. RESULTS: 78.9% of hemangiomas showed typical morphological features. There was no difference between the quantitative values for typical and atypical hemangiomas. There was not significant difference in T2 relaxation times and values of simplified T2 index in hemangiomas measuring £ 2.0 cm and > 2.0 cm. Lesion/liver signal intensity ratios showed significant differences between the two groups. T2 relaxation times, the simplified T2 index and the lesion/liver signal intensity ratios correctly characterized 96.5%, 93%, and 89.5% of the hemangiomas, respectively. CONCLUSION: Quantitative analysis of hepatic hemangiomas is a simple technique that in conjunction with morphological evaluation provides a more reliable characterization of these tumors.

Keywords: Liver, Hemangioma, Magnetic resonance imaging

Magnetic resonance imaging is currently an important method for the assessment of the liver. As with helical computed tomography, the use of fast magnetic resonance imaging sequences to obtain data from the different phases of vascularization allows the detection and identification of tumors. However, some lesions may mimic true parenchymatous lesions which are interpretation pitfalls. These lesions are called pseudolesions and may occur due to perfusion defects, focal fatty infiltration, and spared areas of fatty liver or artifacts, among other causes. The recognition of these lesions is essential to avoid false-positive results. The aim of this study was to classify, illustrate, and briefly describe these pseudolesions, and to provide alternatives to differentiate pseudolesions from true parenchymatous lesions.

Keywords: Liver, Magnetic resonance imaging, Pitfalls

Since the early 1980's several magnetic resonance imaging pulse sequences have been developed in order to determine the optimum imaging technique for the detection and characterization of hepatic lesions. T2-weighted images play an important role in the evaluation of the liver and present equal or greater sensitivity than enhanced computed tomography for the detection of liver lesions. New techniques for obtaining T-2 weighted images have been developed in the attempt to optimize the method. These techniques have improved the image quality by shortening examination time, reducing motion artifacts, and improving contrast-to-noise ratio. The effectiveness of the different techniques (fat suppression, breath-hold, respiratory-triggered and phased-array coils) has been tested in many comparative studies, although the results are controversial. In this article we review the literature and discuss the several T2-weighted image techniques, particularly with regard to sensitivity to detect focal liver lesions.

Keywords: Magnetic resonance imaging, Pulse sequences, Liver tumors, Liver

OBJECTIVE: To assess the degree of acceptance of patients undergoing computed tomography colonography (CTC) in comparison with colonoscopy in the screening of colorectal disease. MATERIALS AND METHODS: Fifty patients with suspected colorectal disease underwent CTC and colonoscopy. Questionnaires were administered before and after the performance of the CTC and after the colonoscopy. The discomfort expected and experienced before and after the performance of both procedures as well as the patients’ preference for each method were evaluated. RESULTS: As regards CTC, before the procedure, 18% of the patients reported expecting little discomfort, 78%, mild discomfort, and 4%, a lot of discomfort. After the procedure, 72% of the patients reported little discomfort, 26%, mild discomfort, and only one (2%) of the patients reported a lot of discomfort. Upon completion of the colonoscopy, 86% of the patients reported their preference for CTC. The degree of colonic distention and residual amount of fluid had no influence on the patients’ preference. Conclusion: CTC was preferred to colonoscopy, with no statistical relationship with the degree of colonic distention at CTC and efficiency of bowel preparation.

Keywords: Colonoscopy; Virtual colonoscopy; Computed tomography colonography; Computed tomography; Patients’ preference; Patients’ satisfaction.

OBJECTIVE: The purpose of this study was to assess the performance of neutral oral contrast agents, comparing intestinal distention, distinction of intestinal wall, acceptance and side effects. MATERIALS AND METHODS: Prospective, randomized, and double-blinded study involving 30 patients who underwent computed tomography of abdomen and pelvis with administration of neutral oral contrast agents, divided into three groups according the contrast agent type: milk, water, and polyethylene glycol. The images were consensually analyzed by two observers, considering the degree of bowel distention and intestinal wall distinction. The patients responded to a questionnaire regarding the taste of the ingested solution and on their side effects. Kruskal-Wallis and chi-square tests were employed for statistical analysis. RESULTS: Among 40 studied intestinal segments, appropriate bowel distension (intestinal loop diameter > 2 cm) was observed in 14 segments (35%) in the milk group, 10 segments (25%) in the water group and 23 segments (57%) in the polyethylene glycol group (p = 0.01). Preparation with polyethylene glycol resulted in the best bowel distention, but it presented the worst taste and highest incidence of diarrhea as reported by patients. CONCLUSION: Bowel preparation with oral polyethylene glycol results in higher degree of bowel distention than with water or milk, but presents worst acceptance related to its taste and frequency of diarrhea as a side effect.

Keywords: X-ray computed tomography; Small bowel; Contrast media.

Computed tomography colonography is a minimally invasive method for screening for polyps and colorectal cancer, with extremely unusual complications, increasingly used in the clinical practice. In the last decade, developments in bowel preparation, imaging, and in the training of investigators have determined a significant increase in the method sensitivity. Images interpretation is accomplished through a combined analysis of two-dimensional source images and several types of three-dimensional renderings, with sensitivity around 96% in the detection of lesions with dimensions equal or greater than 10 mm in size, when analyzed by experienced radiologists. The present pictorial essay includes examples of diseases and pseudolesions most frequently observed in this type of imaging study. The authors present examples of flat and polypoid lesions, benign and malignant lesions, diverticular disease of the colon, among other conditions, as well as pseudolesions, including those related to inappropriate bowel preparation and misinterpretation.

Keywords: Colonography; Computed tomography; Colorectal neoplasm; Colonic polyps.

OBJECTIVE: To map the view of surgeons on the role played by computed tomography colonography (CTC). MATERIALS AND METHODS: An electronic questionnaire was sent to members of the Brazilian College of Surgeons. The questionnaire consisted of 16 multiple-choice questions about demographics and general knowledge about CTC. RESULTS: The authors obtained 144 responses; 90.3% of the specialists were men, 60% with less than 30 years from graduation, 77.1% were gastrointestinal surgeons, 22.9% were general surgeons, 53.5% were involved in academic activity, and 59.7% had their professional activity in cities with more than 500,000 inhabitants. As regards the knowledge about CTC, 84.7% of the respondents knew the method, 70.8% knew how it is performed, 56.9% reported knowing the bowel preparation used for the procedure, 31.3% used the method, and 53.5% knew some CTC service in their city. About half of the respondents did not know the precise indication of the method. The method is most frequently known and used by professionals working in cities with more than 500,000 inhabitants (p < 0.005). There was a tendency of a more frequent use of the method by the professionals pursuing an academic career. CONCLUSION: Despite its infrequent use in Brazil, CTC is a well known method, particularly in large urban centers and in the academic environment.

Keywords: Computed tomography colonography; Computed tomography; Physician's practice patterns.

Hepatic lymphoma can be divided into its primary and secondary forms. To be classified as primary hepatic lymphoma, the disease should be limited to the liver and hilar lymph nodes, with no distant involvement (to the bone marrow or other sites). Primary hepatic lymphoma is quite rare, accounting for less than 1% of all cases of non-Hodgkin lymphoma, whereas secondary hepatic lymphoma affects nearly half of such cases. Familiarity with the imaging features of hepatic lymphoma is important for its early diagnosis and appropriate management. In this essay, we aim to review the roles of computed tomography and magnetic resonance imaging in identifying and monitoring hepatic lymphomas, using sample cases to describe and illustrate the wide spectrum of imaging findings in the primary and secondary forms of this disorder.

Keywords: Lymphoma; Liver; Magnetic resonance imaging; Tomography, X-ray computed.