Small hepatic lesions found on single-phase helical CT in patients with malignancy: diagnostic capability of breath-hold, multisection fluid-attenuated inversion-recovery (FLAIR) MR imaging using a half-fourier acquisition single-shot turbo spin-echo (HASTE) sequence.

PURPOSE: To evaluate the diagnostic capability of breath-hold, multisection fluid-attenuated inversion-recovery (FLAIR) imaging using a half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequence in combination with T2-weighted fast spin-echo (FSE) magnetic resonance (MR) sequences for small hepatic lesions found on CT in patients with malignancy. MATERIALS AND METHODS: This study included 48 patients with extrahepatic malignancy who underwent both CT and MR examinations. There were a total of 112 small hepatic lesions (73 cysts and 39 liver metastases, <2 cm in diameter) that showed low attenuation on enhanced CT. Three radiologists independently reviewed the CT and MR (FLAIR-HASTE and T2-weighted FSE) images and assigned a confidence level to their evaluation (cyst or metastasis) on a five-point scale. RESULTS: All three reviewers were significantly better able (P < 0.05) to differentiate small hepatic cyst from liver metastasis with combined FLAIR-HASTE and T2-weighted FSE images (Az values = 0.997-0.999) than with CT (0.917-0.932). The mean values of sensitivity, specificity, and accuracy were significantly higher (P < 0.001) for T2-weighted FSE with FLAIR-HASTE (96.6%, 96.8%, and 96.7%, respectively) than for CT (76.9%, 61.6%, and 67.3%, respectively). A confident diagnosis was rendered in 12 of 112 lesions (10.7%) on the basis of CT, and this rate increased to 83 of 112 (74.1%) on the basis of T2-weighted FSE and FLAIR-HASTE imaging. CONCLUSION: FLAIR-HASTE is considered to be an effective sequence for differentiating hepatic cysts from liver metastases without the use of a contrast agent. With FLAIR-HASTE one can confidently diagnose small hepatic lesions found on CT in patients with a malignancy.

MR cholangiopancreatography: comparison of images obtained with 1.0 and 1.5 Tesla units.

OBJECTIVE: To compare the image quality and visualization obtained in MR cholangiopancreatography (MRCP) using different high-field strength (1.0 vs. 1.5 Tesla) MR units and to assess the effect of field strength on MRCP. MATERIALS AND METHODS: This study population included 10 healthy volunteers and 37 patients suspected of having pancreatobiliary diseases. MRCP images were obtained using two MR units with different high-field strengths (1.0 and 1.5 Tesla), with half-Fourier acquisition single-shot turbo spin-echo (HASTE) and rapid acquisition by relaxation enhancement (RARE) sequences. The image quality and visualization of each portion of the pancreatobiliary system were graded and recorded using a four-point scale. Additionally, the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured. RESULTS: The SNR and CNR in HASTE sequences acquired with the 1.5 Tesla (T) unit were significantly higher than those acquired with the 1.0 T unit (p=0.001). In qualitative analysis, there were no statistically significant differences in image quality or visualization of the ducts in either HASTE or RARE sequences between 1.0 T and 1.5 T. CONCLUSION: Our study showed that visual image quality provided by MRCP was equivalent at 1.0 and 1.5 T.