Liver-specific magnetic resonance contrast medium in the evaluation of chronic liver disease / Aplicações do contraste hepato-específico de ressonância magnética nas hepatopatias crônicas

ABSTRACT The hepatobiliary-specific contrast medium (gadoxetic acid – Primovist®) is primarily used to improve detection and characterization of focal hepatic lesions, such as in chronic liver disease patients with suspected hepatocellular carcinoma. Since the contrast medium is selectively taken up by functioning hepatocytes in the late hepatobiliary phase, it helps to detect typical hepatocellular carcinoma, which show low signal intensity on this phase. This imaging feature also assists in differentiating regenerative/dysplastic nodules from early hepatocellular carcinomas (with over 90% accuracy), as well as hypervascular hepatocellular carcinomas from arterial pseudo-enhancement foci. Future perspectives include its use in quantification of hepatic function and fibrosis.

RESUMO O contraste hepato-específico (ácido gadoxético – Primovist®) tem como utilidade principal melhorar a detecção e a caracterização de lesões hepáticas focais, por exemplo, em hepatopatas crônicos com suspeita de hepatocarcinoma. Por apresentar captação seletiva por hepatócitos funcionantes na fase hepatobiliar tardia, auxilia na detecção de hepatocarcinomas típicos – a maioria dos quais apresentando hipossinal nessa fase. Essa característica de imagem também auxilia na diferenciação entre nódulos regenerativos/ displásicos e hepatocarcinomas precoces (com mais de 90% de acurácia), e entre hepatocarcinomas hipervascularizados e focos de pseudorrealce arterial. Perspectivas futuras promissoras incluem sua utilização na quantificação de função e de fibrose hepáticas.

Clinically low-risk prostate cancer: evaluation with transrectal doppler ultrasound and functional magnetic resonance imaging

OBJECTIVES: To evaluate transrectal ultrasound, amplitude Doppler ultrasound, conventional T2-weighted magnetic resonance imaging, spectroscopy and dynamic contrast-enhanced magnetic resonance imaging in localizing and locally staging low-risk prostate cancer. INTRODUCTION: Prostate cancer has been diagnosed at earlier stages and the most accepted classification for low-risk prostate cancer is based on clinical stage T1c or T2a, Gleason score <6, and prostate-specific antigen (PSA) <10 ng/ml. METHODS: From 2005 to 2006, magnetic resonance imaging was performed in 42 patients, and transrectal ultrasound in 26 of these patients. Seven patients were excluded from the study. Mean patient age was 64.94 years and mean serum PSA was 6.05 ng/ml. The examinations were analyzed for tumor identification and location in prostate sextants, detection of extracapsular extension, and seminal vesicle invasion, using surgical pathology findings as the gold standard. RESULTS: Sixteen patients (45.7 percent) had pathologically proven organ-confined disease, 11 (31.4 percent) had positive surgical margin, 8 (28.9 percent) had extracapsular extension, and 3 (8.6 percent) presented with extracapsular extension and seminal vesicle invasion. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy values for localizing low-risk prostate cancer were 53.1 percent, 48.3 percent, 63.4 percent, 37.8 percent and 51.3 percent for transrectal ultrasound; 70.4 percent, 36.2 percent, 65.1 percent, 42.0 percent and 57.7 percent for amplitude Doppler ultrasound; 71.5 percent, 58.9 percent, 76.6 percent, 52.4 percent and 67.1 percent for magnetic resonance imaging; 70.4 percent, 58.7 percent, 78.4 percent, 48.2 percent and 66.7 percent for magnetic resonance spectroscopy; 67.2 percent, 65.7 percent, 79.3 percent, 50.6 percent and 66.7 percent for dynamic contrast-enhanced magnetic resonance imaging, respectively. Sensitivity, specificity, PPV, NPV and accuracy values for detecting extracapsular extension were 33.3 percent, 92 percent, 14.3 percent, 97.2 percent and 89.7 percent for transrectal ultrasound and 50.0 percent, 77.6 percent, 13.7 percent, 95.6 percent and 75.7 percent for magnetic resonance imaging, respectively. For detecting seminal vesicle invasion, these values were 66.7 percent, 85.7 percent, 22.2 percent, 97.7 percent and 84.6 percent for transrectal ultrasound and 40.0 percent, 83.1 percent, 15.4 percent, 94.7 percent and 80.0 percent for magnetic resonance imaging. CONCLUSION: Although preliminary, our results suggest that imaging modalities have limited usefulness in localizing and locally staging clinically low-risk prostate cancer.

Acute and chronic mesenteric ischemia: MDCT findings / Isquemia mesentérica aguda e crônica: achados tomográficos

Mesenteric ischemia is caused by a reduction in mesenteric blood flow. It can be divided into acute and chronic, based upon the rapidity and the degree to which the blood flow is compromised. The authors retrospectively reviewed 22 cases of mesenteric ischemia, diagnosed by multidetector computed tomography (MDCT) in our service, and confirmed by surgery or clinical follow-up. The frequency of the diagnostic findings of chronic and acute mesenteric ischemia was evaluated. The improvement of three-dimensional (3D) MDCT allows accurate assessment of mesenteric vessels. Therefore, it demonstrates changes in ischemic bowel segments helpful in determining the primary cause of the disease, and can identify the complications in patients with acute and chronic mesenteric ischemia.

A isquemia mesentérica é causada pela redução do fluxo sanguíneo mesentérico. Essa patologia pode ser dividida em aguda e crônica, baseada na rapidez e no grau em que o fluxo sanguíneo está sendo comprometido. Os autores retrospectivamente revisaram 22 casos de isquemia mesentérica, diagnosticados por tomografia computadorizada com mutidetectores (TCMD) em nosso serviço, e confirmados por cirurgia ou seguimento clínico. Os achados diagnósticos de isquemia aguda e crônica e sua frequência foram avaliados. Os avanços na TCMD 3D (tridimensional) permitiram o acesso detalhado aos vasos mesentéricos. Além disso, é possível demonstrar alterações nos segmentos intestinais, auxiliando na identificação da causa primária da doença e podendo identificar as complicações associadas a isquemia mesentérica e crônica.