OBJECTIVE: To compare both qualitatively and quantitatively six T2-weigthed turbo spin-echo sequences varying the respiratory compensation technique, associating or not fat tissue suppression and using different types of coils. MATERIALS AND METHODS: We performed a prospective study of 71 consecutive patients that were submitted to MRI of the liver using a 1.5T magnet. The six following pulse sequences were used: 1) fat-suppressed respiratory triggered with conventional body coil; 2) breath-hold fat-suppressed with conventional body coil; 3) non-suppressed respiratory triggered with conventional body coil; 4) breath-hold non fat-suppressed with conventional body coil; 5) fat-suppressed respiratory triggered with phased-array multicoil; 6) breath-hold fat-suppressed with phased-array multicoil. Images were analyzed quantitatively by measuring the signal-to-noise ratios and qualitatively by evaluating the sharpness of hepatic contours, visibility of intrahepatic vessels and other segmental landmarks, and the presence of artifacts. RESULTS: The qualitative analysis showed that the mean values obtained with the six sequences were 7.8, 4.6, 7.9, 5.2, 6.7 and 4.6, respectively. The respiratory-triggered sequences were better than the breath-hold sequences in both qualitative and quantitative analysis (p < 0.001). No significant differences in the values of signal-to-noise ratios and in overall image quality rankings were found between the sequences with and without fat suppression (p > 0.05). The sequences using the body coil were similar in terms of image quality (p > 0.05) and better regarding signal-to-noise ratios than those obtained with the phased-array multicoil (p < 0.001). CONCLUSION: Our qualitative and quantitative results suggest that the best MRI sequences for the evaluation of the liver are the sequences with respiratory triggering using a conventional body coil, with or without fat suppression.

Keywords: Magnetic resonance imaging, Liver, Gastrointestinal diagnostic techniques, Imaging techniques

Hemangiomas are benign hepatic tumors that in most cases require no surgical excision if correctly identified. Ultrasound (US) usually shows hyperechogenic tumors although some unusual hypoechogenic hemangiomas have also been described. Fifteen patients with hypoechogenic hemangiomas, identified in a period of approximately four years, were evaluated prospectively. As the US findings of these hemangiomas were atypical, the final diagnosis was established after a combined analysis of US and helical computed tomography (helical-CT) findings. Helical-CT showed centripetal enhancement after administration of intravenous iodinated contrast media in all lesions. The levels of carcinoembrionic antigen and alpha-fetoprotein were measured in all patients who were also submitted to endoscopy and colonoscopy (or double contrast enema). No abnormalities were found in any of these tests. Additionally, US and helical-CT examinations were performed 8 to 12 months after the initial investigation in all patients, and no changes were seen in the appearance and dimensions of the lesions. There was associated steatosis in 14 of the 15 patients with hypoechogenic hemangiomas. The authors concluded that atypical hypoechogenic hemangiomas occur mainly in patients with steatosis and only occasionally in patients with nonsteatotic liver. In these atypical cases complementary imaging and biochemical studies, and follow-up tests are necessary to establish an accurate diagnosis.

Keywords: Liver, Hemangioma, Hypoechogenic hemangioma, Ultrasonography

Pulmonary cryptococcosis is caused by Cryptococcus neoformans, a world-wide distribution unimorphic fungus that exhibits the same form in its natural habitat, animals and humans. The disease presents variable clinical and pathologic features and occurs in immunocompetent and immunocompromised patients. We reviewed the computed tomography findings of 14 patients with confirmed pulmonary cryptococcosis. The most frequent computed tomography findings were masses and pulmonary nodules. Other abnormalities included cavities, areas of consolidation, peribronchovascular interstitial thickening and diffuse linear opacities. Pulmonary masses were the most frequent findings (64.2%), followed by nodules (35.7%) whereas diffuse pulmonary disease accounted for 14.2% of the cases. The most affected areas were the upper lobes and the anterior regions. Computed tomography scan of the chest allows a precise assessment of pulmonary parenchymal involvement in patients with pulmonary cryptococcosis.

Keywords: Radiology, Pulmonary cryptococcosis, Computed tomography

Traumatic mediastinal lesions are unusual findings in patients with thoracic trauma but may represent poor prognosis and be associated with severe lesions. Mediastinal trauma is increasingly being diagnosed by computed tomography due to the fast acquisition times of helical techniques, allowing the evaluation of critically ill patients and the adoption of efficient therapeutic measures. The authors studied 11 patients with mediastinal lesions who were submitted to computed tomography due to thoracic trauma. The most frequent finding was mediastinal bleeding characterized by infiltration of mediastinal fat, dense material within the mediastinal spaces or hematoma. Hemopericardium was the second most common lesion in this series, appearing as dense or liquid material in the pericardium. Aortic lesions such as wall irregularities or pseudoaneurisms were less commonly seen (three patients). In this study blunt thoracic traumas were observed in six cases whereas penetrating trauma occurred in five cases. The causes of blunt trauma were pedestrians struck by car, motor vehicle accidents and falls. Penetrating trauma was due to lesions produced by bullets or knifes.

Keywords: Mediastinal bleeding, Aortic lesion, Computed tomography

The density pattern of the breasts should be reported to the clinician in view of the possible difficulties in the diagnosis of mammary disease due to reduced sensitiveness and specificity in patients with dense breasts. OBJECTIVE: The aim of this paper was to correlate the different mammography density patterns with possibly modifying factors such as age, parity and body mass index. MATERIALS AND METHODS: Eight hundred and forty-nine women and their respective mammography examinations were evaluated in order to identify the density pattern of the breasts, age, parity and body mass index. Chi-square test, contingency coefficient and logistic regression were used for the statistical analysis. RESULTS: Most women were 36 to 55 years old. There was predominance of low density (73.7%) over high density (26.3%) patterns. Multiparity was observed in 69.8% of the women whereas 16.5% were nulliparous and 13.7% had only one child. The body mass index was normal in 53.3% of the women. Overweight was observed in 26.1% of the women, 9.5% were obese and 11.3% were below the ideal weight. CONCLUSION: Dense breast patterns were influenced by young age, nulliparity and reduced body mass index. Low density breast patterns were more frequent with increasing ages, number of children and body mass index.

Keywords: Mammography, Breast radiography, Breast density

OBJECTIVE: The aim of this work was to establish a working standard for intercomparison and calibration of dose calibrators used in most of nuclear medicine facilities for the determination of the activity of radionuclides administered to patients in specific examinations or therapeutic procedures. MATERIALS AND METHODS: A commercial dose calibrator, a set of standard radioactive sources, and syringes, vials and ampoules with radionuclide solutions used in nuclear medicine were utilized in this work. RESULTS: The commercial dose calibrator was calibrated for radionuclide solutions used in nuclear medicine. Simple instrument tests, such as linearity response and variation response with the source volume at a constant source activity concentration were performed. CONCLUSION: This instrument may be used as a reference system for intercomparison and calibration of other activity meters, as a method of quality control of dose calibrators utilized in nuclear medicine facilities.

Keywords: Nuclear medicine, Dose calibrator, Working standard, Intercomparison, Calibration, Quality control

OBJECTIVE: To develop a nomogram for the umbilical cord cross-sectional area (UCCSA) in normal pregnancies in women between 20 to 40 weeks gestation. MATERIALS AND METHODS: A cross-sectional study was developed to determine reference ranges for the UCCSA during normal pregnancies (patients with known dates of last menstrual period, and a normal ultrasound examination before the 20th week of gestation). The measurements of the UCCSA were obtained using a plane adjacent to the insertion of the cord in the abdomen. A 3.5 MHz transabdominal transducer was used on all ultrasound equipment utilized (a Synergy Multi Sync M500, a Toshiba 140 and a Toshiba Corevision). The statistical analysis was performed using the SPSS (Statistical Package for Social Sciences) software. RESULTS: The Kolmogorov-Smirnov test showed a normal distribution of the data and the nomogram was constructed by linear regression. The analysis of variance (F test = 356.27) showed that our model was significant at a p < 0.01 level, and therefore represented adequately the studied population. The confidence interval (95%) contained the real value of the UCCSA. The equation constructed for the UCCSA (y) according to the gestational age (x) was: y = -532.27 + 44.358x - 0,655x². CONCLUSION: The nomogram developed for the UCCSA shows a progressive increase of the UCCSA up to the 32nd week, stabilization until the 34th week, and decrease after the 35th week of gestation.

Keywords: Umbilical cord, Cross-sectional area, Fetal growth

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

Callosal dysgenesis is a malformation of the corpus callosum with origins in the embryogenesis of the telencephalon. We reviewed the computed tomography and magnetic resonance imaging findings of 11 patients with callosal dysgenesis and one patient with normal corpus callosum associated with a lipoma. The patients were divided into three distinct groups: total agenesis (three patients), partial agenesis (six patients) and hypoplasia (two patients). Associated abnormalities were observed in nine patients, including Chiari II malformation (one patient), schizencephaly (one patient), interhemispheric cyst (two patients), Dandy-Walker cyst (one patient), nodular heterotopy (one patient) and lipoma of the corpus callosum (four patients). This paper presents a review that may contribute to the diagnosis of these disorders.

Keywords: Dysgenesis of the corpus callosum, Brain malformation, Developmental anomalies, Lipoma of the corpus callosum

We report a rare case of coexisting bilateral adrenal hemorrhage, right renal vein and inferior vena cava thrombosis in a neonate. Imaging studies played an important role in the diagnosis, management, and follow-up of this patient.

Keywords: Thrombosis, Adrenal glands, Hemorrhage, Neonate, Ultrasound, Computed tomography

Persistent left superior vena cava with absent right superior vena cava is a rare anomaly, with less than 150 cases reported in the literature. Congenitally persistent left superior vena cava is the most common variant of systemic venous return to the heart, resulting embryologically from failure of the left anterior cardinal vein to become obliterated. Its incidence varies from 0.3% in patients with otherwise normal heart to 4.3% in patients with congenital heart disease. In the majority of the patients, a right superior vena cava is present as well, but rarely the right anterior cardinal vein degenerates resulting in the absence of the normal right superior vena cava. The blood from the right side is carried by the persistent left superior vena cava to the right atrium through the coronary sinus. We report the case of a patient with a persistent left superior vena cava and absence of right superior vena cava identified by chance during a chest radiograph and computed tomography examination for investigation of chronic pulmonary obstructive disease. The patient had no congenital heart disease and the blood from the right side was drained by the persistent left superior vena cava into the right atrium through the coronary sinus.

Keywords: Persistent left superior vena cava, Absent right superior vena cava, Chest radiography, Computed tomography