Differential Riagnosis of the Brain Tumor and Brain Abscess: the Usefulness of Dynamic MR Imaging

PURPOSE: To evaluate the usefulness of dynamic MR imaging in the differential diagnosis of intracranial tumorand abscess. MATERIALS AND METHODS: Dynamic MR images of 36 patients with surgically or clinically provenintracranial enhancing lesions were retrospectively reviewed. These lesions comprised 15 metastases, 14 gliomas,and seven abscesses. Images were sequentially obtained every 30 seconds for 3-5 minutes using the spin-echotechnique(TR/TE : 200 msec/15 msec) after bolus injection of gadolinium dimeglumine(2-3cc/sec). The dynamics ofcontrast enhancement of the lesions was analyzed visually and by calculating the sequential contrast-enhancementratio(CER). RESULTS: CER during the 30-second early dynamic phase was 93.16 in metastases, 67.78 in gliomas, and48.3 in abscesses(ANOVA, p<0.005). The contrast enhancement pattern of metastases showed rapidly increased signalintensity(SI) up to 30 seconds, followed by a relatively rapid decrease; less time was then required to reach theCER peak. In gliomas, SI increased gradually up to 180 seconds and then took a longer time to reach the CER peak.The SI of abscesses was similar to that of gliomas, with a more gradual increase for 30-60 seconds and a longertime for the CER peak to be reached. CONCLUSION: The contrast enhancement pattern and CER parameters seen ondynamic MRI can help differentiate intracranial tumor and abscess.

Optimal MR Pulse Sequences for Hepatic Hemangiomas: Comparison of T2-Weighted Turbo-Spin-Echo, T2-Weighted Breath-hold Turbo-Spin-Echo, and T1-Weighted FLASH Dynamic Imaging

PURPOSE: To optimize MR imaging pulse sequences in the imaging of hepatic hemangioma and to evaluate on dynamic MR imaging the enhancing characteristics of the lesions. MATERIALS AND METHODS: Twenty patients with 35 hemangiomas were studied by using Turbo-spin-echo (TSE) sequence (T2-weighted, T2- and heavily T2-weighted breath-hold) and T1-weighted FLASH imaging acquired before, immediately on, and 1, 3 and 5 minutes after injection of a bolus of Gd-DTPA (0.1 mmol/kg). Phased-array multicoil was employed. Images were quantitatively analyzed for lesion-to-liver signal difference to noise ratios (SD/Ns), and lesion-to-liver signal ratios (H/Ls), and qualitatively analyzed for lesion conspicuity. The enhancing characteristics of the hemangiomas were described by measuring the change of signal intensity as a curve in T1-weighted FLASH dynamic imaging. RESULTS: ForT2-weighted images, breath-hold T2-weighted TSE had a slightly higher SD/N than other pulse sequences, but there was no statistical difference in three fast pulse sequences (p=0.211). For lesion conspicuity, heavily T2-weighted breath-hold TSE images was superior to T2-weighted breath-hold or non-breath-hold TSE (H/L, 5.75, 3.81, 2.87, respectively, p<0.05). T2-weighted breath-hold TSE imaging was more effective than T2-weighted TSE imaging in removing lesion blurring or lack of sharpness, and there was a 12-fold decrease in acquisition time (20 sec versus 245 sec). T1-weighted FLASH dynamic images of normal liver showed peak enhancement at less than 1 minute, and of hemangioma at more than 3 minutes; the degree of enhancement for hemangioma decreased after a 3 minute delay. CONCLUSION: T2-weighted breath-hold TSE imaging and Gd-DTPA enhanced FLASH dynamic imaging with 5 minutes delay are sufficient for imaging hepatic hemangiomas.

Optimal MR Pulse Sequences for Hepatic Hemangiomas: Comparison of T2-Weighted Turbo-Spin-Echo, T2-Weighted Breath-hold Turbo-Spin-Echo, and T1-Weighted FLASH Dynamic Imaging

PURPOSE: To optimize MR imaging pulse sequences in the imaging of hepatic hemangioma and to evaluate on dynamic MR imaging the enhancing characteristics of the lesions. MATERIALS AND METHODS: Twenty patients with 35 hemangiomas were studied by using Turbo-spin-echo (TSE) sequence (T2-weighted, T2- and heavily T2-weighted breath-hold) and T1-weighted FLASH imaging acquired before, immediately on, and 1, 3 and 5 minutes after injection of a bolus of Gd-DTPA (0.1 mmol/kg). Phased-array multicoil was employed. Images were quantitatively analyzed for lesion-to-liver signal difference to noise ratios (SD/Ns), and lesion-to-liver signal ratios (H/Ls), and qualitatively analyzed for lesion conspicuity. The enhancing characteristics of the hemangiomas were described by measuring the change of signal intensity as a curve in T1-weighted FLASH dynamic imaging. RESULTS: ForT2-weighted images, breath-hold T2-weighted TSE had a slightly higher SD/N than other pulse sequences, but there was no statistical difference in three fast pulse sequences (p=0.211). For lesion conspicuity, heavily T2-weighted breath-hold TSE images was superior to T2-weighted breath-hold or non-breath-hold TSE (H/L, 5.75, 3.81, 2.87, respectively, p<0.05). T2-weighted breath-hold TSE imaging was more effective than T2-weighted TSE imaging in removing lesion blurring or lack of sharpness, and there was a 12-fold decrease in acquisition time (20 sec versus 245 sec). T1-weighted FLASH dynamic images of normal liver showed peak enhancement at less than 1 minute, and of hemangioma at more than 3 minutes; the degree of enhancement for hemangioma decreased after a 3 minute delay. CONCLUSION: T2-weighted breath-hold TSE imaging and Gd-DTPA enhanced FLASH dynamic imaging with 5 minutes delay are sufficient for imaging hepatic hemangiomas.