OBJECTIVE: This study aimed to explore the functional connectivity of the default mode network (DMN) in crack-cocaine users, in comparison with that observed in age-matched non-drug-using controls. MATERIALS AND METHODS: Inpatient crack-cocaine users who had been abstinent for at least four weeks and age-matched non-drugusing controls underwent resting state functional magnetic resonance imaging. Images were acquired while the subjects rested with their eyes closed. After data preprocessing, DMNs were defined by spatial independent component analysis and seed-based correlation analysis, by chosen regions of interest centered in the ventral anterior cingulate cortex and in the posterior cingulate cortex. RESULTS: The functional connectivity of the DMN determined by independent component analysis did not differ between the crackcocaine users and the controls. However, the seed-based correlation analysis seeking a single metric of functional connectivity between specific brain regions showed that the negative connectivity between the ventral anterior cingulate cortex and the left superior parietal lobule was significantly greater in the crack-cocaine users than in the controls. CONCLUSION: The results suggest that selective extrinsic network connectivity of the DMN related to motor and executive function is impaired during crack-cocaine addiction.

Keywords: Substance-related disorders; Magnetic resonance imaging/methods; Brain/physiopathology; Image interpretation, computer-assisted; Functional neuroimaging.

OBJECTIVE: To evaluate the accuracy of visual analysis and of the coronary artery calcium (CAC) score in nontriggered computed tomography (CT), in comparison with that of the CAC score in electrocardiogram-triggered CT, in identifying coronary calcification. MATERIALS AND METHODS: A total of 174 patients for whom CT was indicated for CAC scoring underwent nontriggered and triggered CT in a 64-channel multislice scanner, in a single session without a change in position. The images were interpreted by a radiologist with seven years of experience in thoracic and cardiovascular radiology. The measurement of coronary calcium was carried out by three methods: CAC score with dedicated software in nontriggered CT, CAC score with dedicated software in triggered CT, and visual analysis without dedicated software in nontriggered CT. RESULTS: In nontriggered CT, the CAC score presented an accuracy of 95.98% (95% CI: 91.93–98.04). The visual analysis showed an accuracy of 97.13% (95% CI: 93.45–98.77). CONCLUSION: Nontriggered CT showed excellent accuracy in the identification and exclusion of coronary calcification, either the CAC score was determined with dedicated software or through visual analysis.

Keywords: Tomography, X-ray computed; Cardiovascular diseases; Coronary disease.

OBJECTIVE: To compare an albumin-bound gadolinium chelate (gadofosveset trisodium) and an extracellular contrast agent (gadobenate dimeglumine), in terms of their effects on myocardial longitudinal (T1) relaxation time and partition coefficient. MATERIALS AND METHODS: Study subjects underwent two imaging sessions for T1 mapping at 3 tesla with a modified look-locker inversion recovery (MOLLI) pulse sequence to obtain one pre-contrast T1 map and two post-contrast T1 maps (mean 15 and 21 min, respectively). The partition coefficient was calculated as ΔR1myocardium/ΔR1blood, where R1 is 1/T1. RESULTS: A total of 252 myocardial and blood pool T1 values were obtained in 21 healthy subjects. After gadolinium administration, the myocardial T1 was longer for gadofosveset than for gadobenate, the mean difference between the two contrast agents being −7.6 ± 60 ms (p = 0.41). The inverse was true for the blood pool T1, which was longer for gadobenate than for gadofosveset, the mean difference being 56.5 ± 67 ms (p < 0.001). The partition coefficient (λ) was higher for gadobenate than gadofosveset (0.41 vs. 0.33), indicating slower blood pool washout for gadofosveset than for gadobenate. CONCLUSION: Myocardial T1 times did not differ significantly between gadobenate and gadofosveset. At typical clinical doses of the contrast agents, partition coefficients were significantly lower for the intravascular contrast agent than for the extravascular agent.

Keywords: Gadolinium; Gadolinium DTPA; Contrast media; Organometallic compounds; Magnetic resonance imaging/methods; Myocardium/pathology.

OBJECTIVE: To analyze the radiological aspects of pulmonary atelectasis in newborns on mechanical ventilation and treated in an intensive care unit, associating the characteristics of atelectasis with the positioning of the head and endotracheal tube seen on the chest X-ray, as well as with the clinical variables. MATERIALS AND METHODS: This was a retrospective cross-sectional study of 60 newborns treated between 1985 and 2015. Data were collected from medical records and radiology reports. To identify associations between variables, we used Fisher’s exact test. The level of significance was set at p < 0.05. RESULTS: The clinical characteristics associated with improper positioning of the endotracheal tube were prematurity and a birth weight of less than 1000 g. Among the newborns evaluated, the most common comorbidity was hyaline membrane disease. Atelectasis was seen most frequently in the right upper lobe, although cases of total atelectasis were more common in the left lung. Malpositioning of the head showed a trend toward an association with atelectasis in the left upper lobe. CONCLUSION: Pulmonary atelectasis is a common complication in newborns on mechanical ventilation. Radiological evaluation of the endotracheal tube placement provides relevant information for the early correction of this condition.

Keywords: Pulmonary atelectasis/diagnostic imaging; Respiration, artificial; Infant, newborn; Premature birth; Infant, low birth weight.

OBJECTIVE: To determine whether there are substantive differences between the initial interpretations of magnetic resonance imaging (MRI) scans acquired at outside facilities and the second-opinion interpretations of radiologists specializing in gynecologic oncology at a tertiary cancer center, among patients referred for endometrial cancer staging. MATERIALS AND METHODS: This was a retrospective, comparative analysis of 153 initial and second-opinion MRI reports for endometrial cancer staging officially submitted for review by radiologists specializing in gynecologic oncology. For each case, the relationship between the initial and second-opinion reports, regarding the suggested diagnosis and the clinically relevant MRI findings reported, was categorized as “agreement” or “disagreement”. Histopathology was used in order to establish the definitive diagnosis. RESULTS: Disagreement was found in 58 (37.9%) of the 153 cases. Second-opinion interpretations reported findings that affected the preoperative cancer staging and could have led to a change in treatment in 38 cases (24.8%); that did not affect the preoperative staging but provided information that was more accurate in 8 (5.2%); and that suggested a new cancer diagnosis in 12 (7.8%). In 37 cases (24.2%), there was a potential for changes in patient care. Among the 58 cases of disagreement, a definitive (histopathological) diagnosis was made in 41 (70.7%). In 31 (75.6%) of those 41 cases, the second-opinion report was more accurate than was the initial report. CONCLUSION: Discordant interpretations of MRI examinations, which can have a substantial effect on the clinical management of patients, appear to be common.

Keywords: Endometrial neoplasm/diagnostic imaging; Referral and consultation; Magnetic resonance imaging; Diagnostic imaging; Tertiary care centers.

OBJECTIVE: To describe the main anatomical variations of the celiac trunk and the hepatic artery at their origins. MATERIALS AND METHODS: This was a prospective analysis of 100 consecutive computed tomography angiography studies of the abdomen performed during a one-year period. The findings were stratified according to classification systems devised by Sureka et al. and Michels. RESULTS: The celiac trunk was “normal” (i.e., the hepatogastrosplenic trunk and superior mesenteric artery originating separately from the abdominal aorta) in 43 patients. In our sample, we identified four types of variations of the celiac trunk. Regarding the hepatic artery, a normal anatomical pattern (i.e., the proper hepatic artery being a continuation of the common hepatic artery and bifurcating into the right and left hepatic arteries) was seen in 82 patients. We observed six types of variations of the hepatic artery. CONCLUSION: We found rates of variations of the hepatic artery that are different from those reported in the literature. Our findings underscore the need for proper knowledge and awareness of these anatomical variations, which can facilitate their recognition and inform decisions regarding the planning of surgical procedures, in order to avoid iatrogenic intraoperative injuries, which could lead to complications.

Keywords: Anatomy; Computed tomography, Celiac artery; Hepatic artery; Liver transplantation.

Diffusion-weighted imaging (DWI) is widely used in protocols for magnetic resonance imaging (MRI) of the female pelvis. It provides functional and structural information about biological tissues, without the use of ionizing radiation or intravenous administration of contrast medium. High signal intensity on DWI with simultaneous low signal intensity on apparent diffusion coefficient maps is usually associated with malignancy. However, that pattern can also be seen in many benign lesions, a fact that should be recognized by radiologists. Correlating DWI findings with those of conventional (T1- and T2-weighted) MRI sequences and those of contrastenhanced MRI sequences is mandatory in order to avoid potential pitfalls. The aim of this review article is the description of the most relevant physiological and benign pathological conditions of the female pelvis that can show restricted diffusion on DWI.

Keywords: Diffusion magnetic resonance imaging; Magnetic resonance imaging; Pelvis/diagnostic imaging.

The sellar/juxtasellar region comprises the bone component of the sella turcica, pituitary gland, cavernous sinus, and suprasellar cistern. Abnormalities in this region can be attributed to underproduction or overproduction of hormones or to the neurological signs and symptoms resulting from the compression of adjacent structures. Magnetic resonance imaging (MRI) is currently the imaging method of choice, having supplanted computed tomography. The aim of this study was to demonstrate the common and uncommon imaging aspects of sellar and juxtasellar changes, which could facilitate the differential diagnosis. We retrospectively evaluated the MRI scans of 70 patients with sellar/juxtasellar abnormalities from didactic files, and report those with more unusual changes, where MRI played an important role in diagnosis. All cases were confirmed histologically or clinical laboratory.

Keywords: Sella turcica; Magnetic resonance imaging; Pituitary gland.

The aim of this pictorial essay is to review the spectrum of fat-containing liver lesions and their characterisation on magnetic resonance imaging with focus on the radiological features that aid in the differential diagnoses. Fat-containing liver lesions comprise a heterogeneous group of tumours with variable imaging findings. Magnetic resonance imaging clearly displays the micro- and macroscopic fat components of the lesions and other characteristic features that are helpful tools to make the differential diagnosis.

Keywords: Fatty liver/diagnostic imaging; Liver neoplasms/diagnostic imaging; Magnetic resonance imaging.