Breath-hold Spoiled Gradient Echo Research Articles

High Spatial Resolution T1-Weighted MR Imaging of Liver and Biliary Tract During Uptake Phase of a Hepatocyte-Specific Contrast Medium

The hypothesis for this prospective study was that T1-weighted respiratory triggered high spatial resolution images of the liver acquired during the uptake phase of a hepatobiliary contrast medium are technically feasible and provide significantly improved image quality compared with breath-hold images. An inversion recovery-prepared spoiled gradient echo sequence was developed that can be obtained with respiratory triggering. This sequence was acquired in 20 patients with a total of 41 focal liver lesions and compared with axial and coronal breath-hold spoiled gradient echo sequences. All 3 sequences were obtained in the hepatobiliary phase after intravenous injection of Gd-EOB-DTPA at a dosage of 0.025 mmol/kg of body weight. Quantitative evaluation measured the contour sharpness index of the common bile duct and calculated the relative contrast between liver lesions (common bile duct, respectively) and liver parenchyma. In the qualitative assessment, 2 readers independently scored the depiction of focal liver lesions and 3 segments of the biliary tract, the sharpness of hepatic vessels, and the level of artifacts. Statistical significance was assumed at P < 0.05. The respiratory-triggered sequence was technically successful in all 20 patients, revealed significantly higher liver-lesion contrast, contour-sharpness index and scores for depiction of focal liver lesions, biliary tree, and sharpness of hepatic vessels compared with the respective breath-hold sequence. The relative contrast between the common bile duct and the liver parenchyma was significantly higher for the coronal breath-hold sequence compared with the respiratory-triggered sequence. No significant difference was found with respect to the level of artifacts. The 2 readers agreed in 77.9% of the qualitative assessments. T1-weighted respiratory triggered high spatial resolution images obtained in the hepatobiliary phase are technically feasible and significantly improve the image quality compared with breath-hold images.

Cardiac T2* and lipid measurement at 3.0 T-initial experience

This study was designed to assess whether breath-hold cardiac multiecho imaging at 3.0 T is achievable without significant image artefacts and if fat/water phase interference modulates the exponential T2* signal decay. Twelve healthy volunteers (mean age 39) were imaged on a Philips Intera 3.0 T MRI scanner. Multiecho imaging was performed with a breath-hold spoiled gradient echo sequence with a seven echo readout (echo times 1.15-8.05 ms, repetition time 11 ms) using a black-blood prepulse and volume shimming. T2* values were calculated with both mono- and biexpoential fits from the mean signal intensity of the interventricular septum. The global mean T2* was 27.3 ms +/- 6.4. The mean signal-to-noise ratio (SNR) of the septum was 22.8 +/- 9.9, and the contrast-to-noise ratio (CNR) of the septum to the left ventricular cavity 20.3 +/- 9.4. A better fit was obtained with a biexponential model and the mean fat fraction derived was 3.7%. Cardiac functional parameters were in the normal range and showed no correlation with T2*. Cardiac T2* estimation with gradient multiecho imaging at 3.0 T can be achieved with minimal artefact and modelling the signal decay with a biexponential function allows estimation of myocardial lipid content as well as T2* decay.

Granulomatous hepatitis: MRI findings

The purpose of this study was to describe the magnetic resonance imaging findings of granulomatous hepatitis on T1-weighted, T2-weighted and postgadolinium images. Eight patients with histopathological diagnosis of granulomatous hepatitis were evaluated in this study. MRI examinations included precontrast T1-weighted breath-hold spoiled gradient echo, breathing independent STIR sequences, and T1-weighted breath-hold spoiled gradient-echo sequence following after i.v. gadolinium administration in arterial, intermediate and late phases. Diffuse nodular liver involvement was visualized in all patients. Nodules were consistent with granulomas and were 0.5–4.5 cm in diameter. Caseating granulomas were intermediate and high signal on T2-weighted, low signal on T1-weighted images. They revealed no enhancement in two patients, and enhanced in one patient. Noncaseating granulomas revealed intermediate signal on T1, and T2-weighted images and increased enhancement on arterial phase images with persisting enhancement in late phase images. Portal lymph nodes were visible in five patients. Splenomegaly was present in five patients. Granulomatous hepatitis has spectrum of MRI features, to be considered in differential diagnosis with other diffuse nodular liver pathologies.

Pancreatic carcinoma and fast MR imaging: technical considerations for signal intensity difference measurements

The aim of the study was to find the fast magnetic resonance imaging (MRI) sequence with the best conspicuity of pancreatic lesions at 1.0 T and 1.5 T. A total of 51 patients were studied. At 1.0 T, 22 patients with verified malignant pancreatic lesions were studied using the T1-weighted breath-hold spoiled Gradient Echo 2D FLASH(75) or FLASH(80) sequences, both non-enhanced and enhanced with gadolinium. The relative signal intensity difference (SIDR) between lesion and pancreas was measured. At 1.5 T, 20 patients with primary malignant lesions of the pancreas, and nine patients with 13 benign cystic lesions were examined with the breath-hold T2-weighted TrueFISP, HASTE, T1-weighted 2D FLASH(80) and FLASH(50) fat saturation sequences, the latter also enhanced. The signal intensity (SI) values of the pancreas and lesions as well as the pancreatic standard deviation (S.D.) were assessed, and the contrast-to-noise ratio (C/N) was determined. Statistical significances were calculated using an analysis of variance. No statistically significant difference between the sequences used in the conspicuity of cancer was found, either at 1.0 T or at 1.5 T. At 1.5 T, the T2-weighted TrueFISP and HASTE sequences could differentiate benign, cystic lesions from malignant lesions.

Chorioangioma: antenatal diagnosis with fast MR imaging

We report a case of chorioangioma of the placenta, in which fast magnetic resonance imaging (MRI) was useful adjunct to ultrasonography for the antenatal diagnosis. MRI allowed clear demonstration of 6.8 × 6.0 cm solid placental mass along with hydramnios and anatomically normal fetus. On T 1-weighted breath-hold spoiled gradient-echo (fast low-angle shot [FLASH]) images, chorioangioma was mostly isointense to the placenta, but had an area of high signal intensity near the base and at the periphery, suggestive of hemorrhage. On T 2-weighted half-Fourier single-shot fast spin echo (HASTE) images, the mass showed heterogeneous high signal intensity, but had an area of low signal intensity near the surface.

Hepatic alveolar echinococcosis: MRI findings

The purpose of this study was to describe the magnetic resonance imaging (MRI) appearance of hepatic alveolar echinococcosis (HAE) on T 1-weighted, T 2-weighted and postgadolinium images. A total of 13 lesions were demonstrated in 13 patients. All patients underwent MR examination at 1 T imager. MR examinations included precontrast T 1-weighted breathing averaged spin echo (SE), breath-hold spoiled gradient echo, T 2-weighted TSE sequences with and without fat suppression, and T 1-weighted breath-hold spoiled gradient echo (SGE) sequence following i.v. after gadolinium administration. All lesions were confirmed with histopathology. HAE hepatic lesions revealed geographic patterns of variable signal intensities on noncontrast T 1- and T 2-weighted images. Slightly hyperintense, iso- and hypointense signal on T 1-weighted images corresponded to calcified regions, which appeared hypo-isointense signal on T 2-weighted images. Necrotic areas were hypointense signal on T 1-weighted and hyperintense signal on T 2-weighted images. On postgadolinium images, lesions did not reveal enhancement. Dilatation of intrahepatic bile ducts distal to HAE abscesses were observed in five patients and portal vein invasion or compression was observed in four patients, lobar atrophy of the liver was coexistent finding in cases with portal vein compression. The MRI appearance of HAE abscesses included large irregularly marginated masses with heterogenous signal on T 1- and T 2-weighted images and lack of enhancement with gadolinium.

MRI of pancreatic tumors.

MRI employing current imaging techniques is able to detect various pancreatic tumors well, and is able to stage and characterize tumors accurately. This review article describes various current MR techniques emphasizing breath hold spoiled gradient echo (SGE) imaging, fat suppression, dynamic gadolinium administration and MR cholangiographic techniques. Pancreatic ductal adenocarcinomas are generally low signal intensity on T1-weighted and T2-weighted images and enhance poorly on immediate post gadolinium SGE images. Islet cell tumors are generally low signal intensity on T1-weighted images, high signal intensity on T2-weighted images and enhance intensely on immediate post gadolinium images. The appearances of less common tumors is also described.