Gadolinium-enhanced Fast Low-angle Shot Research Articles

3.0T MR Coronary Angiography after Arterial Switch Operation for Transposition of The Great Arteries—Gd-FLASH Versus Non-Enhanced SSFP. A Feasibility Study

Background: Patency of the coronary arteries is an issue after reports of sudden cardiac death in patients with transposition of the great arteries (TGA) operated with arterial switch (ASO). Recent studies give rise to concern regarding the use of ionising radiation in congenital heart disease, and assessment of the coronary arteries with coronary MR angiography (CMRA) might be an attractive non-invasive, non-ionising imaging alternative in these patients. Theoretically, the use of 3.0T CMRA should improve the visualisation of the coronary arteries. The objective of this study was to assess feasibility of 3.0T CMRA at the coronary artery origins by comparing image quality with non-contrast CMRA in ASO TGA patients to healthy age-matched controls, and by comparing image quality with non-contrast CMRA to contrast enhanced CMRA in the patient group. Material and methods: Twelve patients, 9-15 years (mean 11.9 years, standard deviation 1.5 years), and 12 age-matched controls (mean 12.7 years, standard deviation 1.7 years) were examined with 3D balanced steady-state free precession (SSFP). Nine of twelve patients had Gadolinium-enhanced fast low-angle shot (Gd-FLASH) performed after SSFP. Image quality at the coronary artery origins was evaluated subjectively with a 10 cm figurative visual analogue scale (fVAS) and objectively by signal-to-noise and contrast-to-noise ratio (SNR, CNR). Results: All, but one, coronary artery origins were identified. No significant difference in image quality scores was found between patients and controls with SSFP (mean values 6.5 cm—9.1 cm in patients and 7.0 cm—8.0 cm in controls, p-values > 0.1). With SSFP, intra-observer fVAS mean score was 6.7 cm—8.6 cm and with Gd-FLASH 7.7 cm—8.7 cm. CNR was higher with Gd-FLASH (p < 0.03). Intra-observer agreement index (AI) with SSFP was moderate-to-good (0.43–0.71) and with Gd-FLASH good (0.64–0.79) in all origins. Inter-observer AI was good in the left main stem (LMS) with SSFP (0.65). With Gd-FLASH inter-observer AI was good in LMS (0.78) and moderate (0.5) in the left anterior descending artery, but lacking in the other origins though with a good agreement on Bland-Altman plots. Conclusions: Our findings indicate a better, more reproducible image quality with Gd-FLASH than with non-contrast SSFP CMRA on 3.0T for evaluation of the coronary artery origins in ASO TGA children and adolescents.

Diffuse myocardial fibrosis in adolescents operated with arterial switch for transposition of the great arteries - A CMR study

Diffuse myocardial fibrosis in adolescents operated with arterial switch for transposition of the great arteries - A CMR study

MR Imaging in Patients with Crohn Disease: Value of T2- versus T1-weighted Gadolinium-enhanced MR Sequences with Use of an Oral Superparamagnetic Contrast Agent

To prospectively compare oral contrast-enhanced T2-weighted half-Fourier rapid acquisition with relaxation enhancement (RARE) magnetic resonance (MR) imaging with T1-weighted gadolinium-enhanced fast low-angle shot (FLASH) MR and standard examinations in the evaluation of Crohn disease. Institutional review board approval and informed consent were obtained. Fifty-nine patients with Crohn disease underwent MR imaging after oral administration of a superparamagnetic contrast agent; RARE plain and fat-suppressed sequences and FLASH sequences were performed before and after intravenous injection of gadolinium chelate. References were endoscopic, small-bowel barium, computed tomographic, ultrasonographic, and clinical-biochemical scoring of disease activity. Two radiologists analyzed MR images for presence and extent of Crohn disease lesions, presence of strictures or other complications, and degree of local inflammation. MR findings were correlated with endoscopic, radiologic, and clinical data (kappa statistic and Spearman rank correlation test). T2-weighted MR was 95% accurate, 98% sensitive, and 78% specific for detection of ileal lesions. Agreement between T1- and T2-weighted images ranged from 0.77 for ileal lesions to 1.00 for colic lesions. T2-weighted MR enabled detection of 26 of 29 severe strictures, 17 of 24 enteroenteric fistulas, and all adhesions and abscesses; T1-weighted MR enabled detection of 20 of 29 severe strictures, 16 of 24 enteroenteric fistulas, and all adhesions and abscesses. Complications leading to surgery were found in 12 (20%) patients; these were assessed correctly with either T1- or T2-weighted images. T2-weighted signal intensities of the wall and mesentery correlated with biologic activity (P < .001, r of 0.774 and 0.712, respectively). Interobserver agreement was 0.642-1.00 for T2-weighted and 0.711-1.00 for T1-weighted images. T2-weighted MR can depict Crohn disease lesions and help assess mural and transmural inflammation with the same accuracy as gadolinium-enhanced T1-weighted MR. Combination of gadolinium-enhanced T1- and T2-weighted sequences is useful in the assessment of Crohn disease.

Periportal contrast enhancement and abnormal signal intensity on state-of-the-art MR images.

eriportal contrast enhancement and abnormal signal intensity on MR imaging are nonspecific but important signs of pathologic insult to the portal tracts. These findings should be actively sought in patients who undergo abdominal MR examinations because these findings may be the only abnormalities identified. The significance of these findings depends on the underlying pathologic process affecting the portal tracts of the liver. Periportal contrast enhancement and abnormal signal intensity can be invaluable in the detection of bile duct, pancreatic, and gallbladder diseases and in depiction of periportal lymphedema resulting from benign and malignant causes. These findings may also be useful signs of diffuse hepatic injury due to viral and bacterial infections and malignant cell infiltration involving the portal tracts. This pictorial essay illustrates the spectrum of causes of periportal enhancement and abnormal signal intensity using state-of-the-art MR imaging. We used predominantly half-Fourier acquisition single-shot turbo spin-echo (HASTE) T2-weighted images and gadolinium-enhanced fast low-angle shot (FLASH) T1-weighted sequences obtained with fat saturation.

Detectability of Hepatocellular Carcinoma: Comparison of Gd-DT PA-Enhanced and SPIO-Enhanced MR Imaging

Purpose : To compare the detectability of hepatocellular carcinoma (HCC) using superparamagnetic iron oxide (SPIO)-enhanced T2-weighted turbo spin echo (TSE), SPIO-enhanced -weighted FISP, and dynamic Gd-DTPA-enhanced fast low-angle shot (FLASH) MR images. Materials and Methods : In order to assess their hepatic lesions, 25 patients (20 men and 5 women) with HCC were enrolled in an MR study in which both gadolinium and SPIO were used. Since the lesions were most conspicuous during the phase of dynamic arterial dominant phase of dynamic gadolinium-enhanced imaging, this was the phase used for analysis. Images were analyzed qualitatively and quantitatively, and to compare the diagnostic value of gadolinium-enhanced imaging with that of SPIO-enhanced imaging for the detection of HCCs, a receiver-operated characteristic curve was obtained. Results : Qualitative analysis revealed a significantly higher percentage of signal loss and a higher liver-lesion contrast-to-noise ratio on SPIO-enhanced FISP imaging than on SPIO-enhanced T2-weighted TSE imaging (p0.05). It also showed that the lesions were most clearly visible on SPIO-enhanced FISP imaging(and signifi-cantlyso), followed by SPIO-enhanced T2-weighted TSE imaging, and dynamic gadolinium-enhanced imag-ing. Imaging artifacts were more prominent on SPIO-enhanced T2-weighted TSE than on SPIO-enhanced PISF imaging or dynamic gadolinium-enhanced imaging(p0.05). According to ROC analysis, SPIO-enhanced T2-weighted turbo spin echo(TSE) or SPIO-enhanced FISP imaging achieved higher accuracy than did dynamic gadolinium-enhanced FLASH imaging(p0.05). Conclusion : For the detection of hepatocellular carcinomas, SPIO-enhanced MR imaging is better than gadolinium-enhanced FLASH imaging.

Menstrual cycle and age: influence on parenchymal contrast medium enhancement in MR imaging of the breast.

To evaluate the influence of menstrual cycle and age on parenchymal contrast medium enhancement in magnetic resonance (MR) imaging of the breast. Dynamic gadolinium-enhanced fast low-angle shot, three-dimensional breast MR imaging was performed with high temporal and spatial resolution (eight measurements in 10 minutes). Menstrual cycle evaluations and age-influence studies were performed in 44 patients aged 27-55 years with a regular cycle (mean age, 41.5 years) and in 103 patients aged 15-79 years (mean age, 49.3 years), respectively. A region of interest was placed in each quadrant of the breast for evaluation of parenchymal enhancement. Quadrants with complete involution or lesions and patients who received hormonal therapy were excluded [corrected]. Analysis of variance was performed. Parenchymal contrast medium enhancement in cycle days 7-20 (geometric mean enhancement at minutes 1-10 = 0.12-0.47) was significantly lower than that in cycle days 21-6 (geometric mean, 0.17-0.98; P < or = .001). Contrast medium enhancement in patients aged 35-50 years (mean enhancement, 0.17-0.75) was significantly higher than that in patients aged younger than 35 years or older than 50 years (mean enhancement, 0.12-0.40; P < .01). Patients showed statistically significantly lower parenchymal enhancement in menstrual cycle days 7-20 than in days 21-6. Patients aged 35-50 years yielded higher parenchymal enhancement than did younger patients and older patients.

Spin-echo and dynamic gadolinium-enhanced FLASH MR imaging of hepatocellular carcinoma: correlation with histopathologic findings.

Evaluation of histologic subtype and degree of differentiation in hepatocellular carcinoma (HCC) is essential because it affects patient prognosis and treatment planning. To evaluate the histologic subtype of HCC with magnetic resonance (MR) imaging, conventional spin-echo and dynamic studies were correlated with histopathologic and angiographic findings in 72 HCCs. Dynamic MR imaging was performed with the fast low-angle shot (FLASH) technique after administration of gadopentetate dimeglumine. There was considerable overlap in signal intensity between various tumor grades on both T1- and T2-weighted images. On dynamic MR images, the peak contrast enhancement ratio correlated with tumor grade (well-differentiated, 29.5 +/- 24.7; moderately differentiated, 63.5 +/- 24.1; poorly differentiated, 86.9 +/- 26.4) or degree of dilatation of the sinusoidlike vascular space between tumor cells. The maximum contrast-to-noise ratio in tumor (relative to surrounding liver) was achieved within 60 seconds in 45 HCCs (mostly of the trabecular or pseudoglandular type). Enhancement was slight or minimal in 17 tumors (mostly small, well-differentiated tumors). In 10 tumors, the degree of enhancement increased with time, with maximum enhancement in the delayed phase (most frequently in scirrhous HCC). These dynamic patterns correlated with angiographic findings. These data indicate that the degree and pattern of enhancement on dynamic MR images reflect tumor differentiation and architecture of HCC.

Islet cell tumors: comparison of dynamic contrast-enhanced CT and MR imaging with dynamic gadolinium enhancement and fat suppression.

Ten patients with 11 islet cell tumors underwent dynamic contrast material-enhanced computed tomography (CT) and magnetic resonance (MR) imaging within a 1-month period. MR imaging depicted all 11 tumors, and CT depicted seven of the 11 tumors. CT did not depict four of seven tumors that measured 2.5 cm in diameter or less. Islet cell tumors had low signal intensity on T1-weighted fat-suppressed MR images, and gastrinomas were best shown with this technique. Two of three insulinomas less than 1.5 cm in diameter were best shown on dynamic contrast-enhanced fast low-angle shot (FLASH) images as uniform areas of high signal intensity. Hepatic metastases were seen in five patients and showed peripheral ringlike enhancement best demonstrated on dynamic gadolinium-enhanced FLASH images. Hepatic lesions were most conspicuous on T2-weighted fat-suppressed spin-echo images. MR imaging with dynamic gadolinium enhancement and fat suppression is a promising tool in the investigation of islet cell tumors.