T1-weighted FLAIR MR Imaging for the Evaluation of Enhancing Brain Tumors: Comparison with Spin Echo Imaging

PURPOSE: Spin-echo (SE) technique is most commonly used pulse sequence for T1-weighted MR imaging. T1-weighted fluid-attenuated inversion recovery (T1FLAIR) is a relatively new pulse sequence and it provides higher tissue contrast between the gray matter (GM) and white matter (WM) of the brain than T1-weighted SE (T1SE) sequence. However, there has been controversy for the evaluation of enhancing brain tumors with T1FLAIR compared to T1SE. The purpose of this study was to compare T1FLAIR and T1SE sequences for the evaluation of enhancing intracranial tumors. MATERIALS AND METHODS: Fifty-two patients with enhancing brain tumors were evaluated with contrast-enhanced (CE) T1SE and T1FLAIR imaging. Eight quantitative criteria were calculated: lesion-to-WM contrast ratio (CR) and contrast-to-noise ratio (CNR), lesion-to-GM CR and CNR, lesion-to-CSF CR and CNR, and WM-to-GM CR and CNR. For qualitative evaluation, two radiologists assessed lesion conspicuity on CE T1SE and T1FLAIR sequences with three-scale: 1, T1SE superior; 2, sequence equal; T1FLAIR superior. RESULTS: Seventy-nine tumors (31 primaries, 48 metastases) were assessed. For quantitative measurement, the T1FLAIR lesion-to-GM, lesion-to-CSF, WM-to-GM CR and CNR values were comparable and statistically superior to those of the T1SE images (p < 0.001 in all). However, lesion-to-WM CR and CNR were similar on both two sequences without statistically significant difference (p = 0.661, 0.662, respectively). For qualitative evaluation, both radiologists assessed that T1FLAIR images were superior to T1SE images for the evaluation of lesion conspicuity. CONCLUSION: For the evaluation of enhancing intracranial tumors, T1FLAIR sequence was superior or comparable to T1SE sequence.

MR Imaging of the Internal Auditory Canal and Inner Ear at 3T: Comparison between 3D Driven Equilibrium and 3D Balanced Fast Field Echo Sequences

OBJECTIVE: To compare the use of 3D driven equilibrium (DRIVE) imaging with 3D balanced fast field echo (bFFE) imaging in the assessment of the anatomic structures of the internal auditory canal (IAC) and inner ear at 3 Tesla (T). MATERIALS AND METHODS: Thirty ears of 15 subjects (7 men and 8 women; age range, 22-71 years; average age, 50 years) without evidence of ear problems were examined on a whole-body 3T MR scanner with both 3D DRIVE and 3D bFFE sequences by using an 8-channel sensitivity encoding (SENSE) head coil. Two neuroradiologists reviewed both MR images with particular attention to the visibility of the anatomic structures, including four branches of the cranial nerves within the IAC, anatomic structures of the cochlea, vestibule, and three semicircular canals. RESULTS: Although both techniques provided images of relatively good quality, the 3D DRIVE sequence was somewhat superior to the 3D bFFE sequence. The discrepancies were more prominent for the basal turn of the cochlea, vestibule, and all semicircular canals, and were thought to be attributed to the presence of greater magnetic susceptibility artifacts inherent to gradient-echo techniques such as bFFE. CONCLUSION: Because of higher image quality and less susceptibility artifacts, we highly recommend the employment of 3D DRIVE imaging as the MR imaging choice for the IAC and inner ear.

A Narrow Internal Auditory Canal with Duplication in a Patient with Congenital Sensorineural Hearing Loss

A narrow internal auditory canal (IAC) with duplication is a rare anomaly of the temporal bone. It is associated with congenital sensorineural hearing loss. Aplasia or hypoplasia of the vestibulocochlear nerve may cause the hearing loss. We present an unusual case of an isolated narrow IAC with duplication that was detected by a CT scan. In this case, the IAC was divided by a bony septum into an empty stenotic inferoposterior portion and a large anterosuperior portion containing the facial nerve that was clearly delineated on MRI.

Postcontrast T1-weighted Brain Magnetic Resonance Imaging in Pediatric Patients: Comparison Between Postcontrast Fat-suppression Imaging and Conventional T1-weighted or Magnetization Transfer Imaging

PURPOSE: We wished to assess the merits and weaknesses of postcontrast fat-suppression (FS) brain MR imaging in children for the evaluation of various enhancing lesions as compared with postcontrast conventional T1-weighted or magnetization transfer (MT) imaging. MATERIALS AND METHODS: We reviewed the records of those patients with enhancing lesions on brain MR imaging who had undergone both FS imaging and one of the conventional T1-weighted or MT imaging as a postcontrast T1-weighted brain MR imaging. Thirty-one patients (21 male, 10 female; mean age, 8.7 years) with 38 enhancing lesions (18 intra-axial, 16 extra-axial and 4 orbital locations) were included in this study. There were 27 pairs of FS and conventional imagings, and 13 pairs of FS and MT imagings available for evaluation. Two radiologists visually assessed by consensus the lesions' conspicuity, and they also looked for the presence of flow or susceptibility artifacts in a total of 40 pairs of MR imagings. For 19 measurable lesions (14 pairs of FS and conventional T1-weighted imagings, 5 pairs of FS and MT imagings), the contrast ratios between the lesion and the normal brain ([SIlesion-SIwater]/[SInormal brain-SIwater]) were calculated and compared. RESULTS: Compared with conventional imaging, the lesion conspicuity on FS imaging was better in 10 cases (7 extra-axial lesions, 2 orbital lesions and 1 fat-containing intra-axial lesion), equal in 16 cases, and worse in one case. Compared with MT imaging, the lesion conspicuity on FS imaging was better in 3 cases (2 extra-axial lesions and 1 intra-axial lesion), equal in 8 cases, and worse in 2 cases. Image quality of FS imaging was compromised by flow or susceptibility artifacts for 7 patients. The contrast ratios for FS imaging were not significantly different from those for conventional imaging (2.2+/-0.7 vs. 2.2+/-0.6, respectively, p=0.914) and they were significantly lower than those for MT imaging (2.4+/-0.8 vs. 4.5+/-1.5, respectively, p=0.018). CONCLUSION:Postcontrast FS brain MR imaging appears to be better than the conventional T1-weighted imaging and comparable to MT imaging for the visual assessment of enhancing lesions. Especially, the FS imaging has the merit to delineate orbital and extra-axial enhancing lesions or fat-containing lesions, whereas it is disadvantageous when flow or susceptibility artifacts occur.

Diagnostic value of combined LAVA and DWI for pancreatic carcinoma / 第三军医大学学报

Objective To evaluate the combination of LAVA and DWI in diagnosis of pancreatic carcinoma.Methods MRI of 24 patients pathologically confirmed to have pancreatic carcinoma were retrospectively analyzed.MRI sequences included FS T1WI,FS T2WI,enhanced multi-phasic LAVA scanning and DWI.Images quality of all sequences was assessed.SIR of tumor/pericancerous tissue in LAVA,DWI,T1WI and T2WI was compared.ADC values of the cancer,pericancerous tissue were statistically analyzed.The detection rate and accuracy of single sequence and those of the combination of LAVA and DWI were compared.The LAVA evaluation of peripancreatic vascular involvement was compared with surgical findings.Results Images quality of LAVA was higher than the others(P

Comparison between FLAIR Images and T2-weighted Fast Spin-echo Images of Cerebral Territory and Lacunar Infarction

PURPOSE: To assess the significance of fluid-attenuated inversion recovery (FLAIR) magnetic resonance (MR) imaging in the diagnosis of intracranial infarctions and to find out differential points between central lacunar infarctions and perivascular spaces. MATERIALS AND METHODS: We consecutively selected 25 cases of territorial infarction in 20 patients, 37 cases of central infarction in 40 patients, and 30 patients with perivascular space. Signal intensity and lesion conspicuity were analyzed and compared between FLAIR and FSE T2-weighted images, and differences in signal intensity between central infarction and perivascular spaces were determined. RESULTS: Lesion conspicuity for FLAIR was better than for T2-weighted images in 12 and 15, worse in 4 and 24, and similar in 9 and 16 of territorial and central infarctions, respectively. In nine cases of territorial and one case of central infarction, there was associated hemorrhage. At FLAIR imaging, perivascular spaces showed a fine round low signal without a peripheral high signal rim in 17 patients but no demonstrable signals in 15. Differential diagnosis of perivascular spaces and central infarction was thus not difficult. CONCLUSION: FLAIR MRI was useful in the diagnosis of infarctions and in differentiating between central small lacular infarctions and perivascular spaces.

Detection of Acute Intraventricular Hemorrhage: Comparison of FLAIR MR Imaging with Unenhanced CT

PURPOSE: To compare the usefulness of fluid-attenuated inversion recovery (FLAIR) MR imaging with that of unenhanced CT in the detection of acute intraventricular hemorrhage (IVH). MATERIALS AND METHODS: Thirty-four patients with acute IVH underwent FLAIR MR imaging and unenhanced CT within three days of the onset of symptoms. Except in one patient, all MR studies were performed after CT. The mean time intervals between CT and symptom onset and between CT and MR examinations were six and five hours, respectively. Two radiologists evaluated the detectability and conspicuity of acute IVH at FLAIR MR imaging and unenhanced CT. Positive imaging criteria in the detection of acute IVH were intraventricular hyperintensity at FLAIR MRI and hyperattenuation at CT. RESULTS: Acute IVH was detected in all patients at FLAIR MR imaging and in 30 (88%) of 34 patients at unenhanced CT. In 32 patients (94%), the conspicuity of IVH at FLAIR MR imaging was as good as or better than that at unenhanced CT. CONCLUSION: FLAIR MR imaging was superior to unenhanced CT in the detection of acute IVH.

The Usefulness of STIR Image in Breast MRI

PURPOSE: To assess the usefulness of STIR (short tau inversion recovery) imaging in breast MRI (magnetic resonance imaging). MATERIALS AND METHODS: We retrospectively reviewed T1- and T2-weighted (T1WI, T2WI), STIR, and dynamically enhanced images of 44 pathologically confirmed breast lesions (benign, 13; malignant, 31) in 36 patients. We selected the dynamically image which best depicted a particular lesion, and then made hard copy of the corresponding T1WI, T2WI, and STIR images. Using the dynamically enhanced image as a standard, we analysed these in terms of parenchymal pattern, lesion detectability, differentiation between benign and malignant lesions, extent, multifocality, and the ductal system. The results were statistically analyzed. RESULTS: In 33 of 44 cases (75%), detectability was greater at STIR imaging than at T1- and T2WI, especially in fibrofatty or fatty breast (14/14 cases, p<0.05). STIR images did not always differentiate between benign and malignant lesions, and extent (50%) and multifocality (46%) were commonly exaggerated compared with T1- and T2WI. In 18 of 44 cases (41%), STIR images suggested the presence of ductal structures. CONCLUSION: For the detection of lesions, STIR imaging was more useful than T1- and T2WI, though STIR did not differentiate between benign and malignant lesions. The extent and multifocality of a lesion were exaggerated on STIR images, compared with T1- and T2WI.

Detection of Acute Subarachnoid Hemorrhage: Comparison of FLAIR MR Imaging with Unenhanced CT

PURPOSE: Our aim was to evaluate the usefulness of fluid-attenuated inversion recovery (FLAIR) MR imaging for detection of acute subarachnoid hemorrhage (SAH) compared with unenhanced CT. MATERIALS AND METHODS: We compared FLAIR MR images with unenhanced CT scans in 28 patients with acute SAH. Findings of SAH on CT and MR images were graded as 0 (absence), 1 (suspicious), 2 (definite) in the cerebral sulci, sylvian fissure, basal cistern, and cisterns of the posterior fossa. We also compared FLAIR MR images of 28 patients with those of 35 normal subjects, and then the sensitivity, specificity, and diagnostic accuracy of FLAIR MR image for detection of acute SAH were calculated. RESULTS: FLAIR MR image was superior to CT in detecting SAH in the posterior fossa (1.41+/-.74 vs 0.78+/-.80; p<0.05) and cortical sulci(1.11+/-.80 vs 0.70+/-.83; p<0.05). There was no significant difference between FLAIR MR image and CT in detecting SAH in the basal cistern and sylvian fissure. The sensitivity, specificity, and diagnostic accuracy of FLAIR MR image for detection of SAH were 100% in all. CONCLUSION: FLAIR MR image is useful in detecting acute SAH, especially in patients with small amount of SAH or SAH in the posterior fossa.

The Application of FLAIR in Brain Using Low Field Strength MR / 实用放射学杂志

Objective MRI Appearences were analyzed after undergoing the examination of fluid attenuated inversion pulse sequences(FLAIR),in order to evaluate the value of the clinical application of FLAIR in low field.Methods 32 cases were analysed comparatively after undergoing the examination of FLAIR sequence and conventional SE sequence.Results The lesions around the ventrical and the surface of cerebral cortex can be showed clearly in FLAIR sequence in low field.Lesions in ventricles and cistens were shown more distinctly in FLAIR sequence than those in conventional SE sequence.With the aid of enhancement scan by conventional SE sequence,the range and the internal structures of the lesions can be manifested clearlier than those in conventional SE sequence.Conclusion In low field the examination of FLAIR sequence is of great value of clinic diagnosis.

FLAIR-HASTE Sequence in Differential Diagnosis of Focal Hepatic Lesions

PURPOSE: To assess the feasibility of using the FLAIR (fluid-attenuated inversion recovery)-HASTE (half-fourier acquisition single-shot turbo spin-echo) sequence for the differential diagnosis of focal hepatic lesions. MATERIALS AND METHODS: During a 12-month period, 80 patients with 127 focal hepatic lesions [hemangiomas (n=60), hepatocellular carcinomas (HCC) (n=27), cysts (n=25), and metastases (n=15)] underwent MR imaging using a 1.5-T scanner. Verification of the diagnosis was based on the findings of pathology (n=11), of angiography and clinical investigation (n=17), or of dynamic contrast-enhanced MR imaging (n=99). MR sequences included T2-weighted HASTE (TE, 134 ms; echo space, 4.4 ms), FLAIR-HASTE (TE, 64 ms; echo space, 4.4 ms; inversion time, 2000 ms; number of slices, 5 -9; acquisition time, 13 -20 s), and dynamic gadolinium-enhanced T1-weighted FLASH (TR, 131 ms; TE, 4 ms). FLAIR-HASTE imaging was of any focal lesions seen on T2-weighted HASTE images was performed in the liver area, and their signal intensity was classified in one of five ways: very high (higher than the spleen), moderately high (similar to the spleen), slightly high (higher than the liver and lower than the spleen), intermediate (similar to the liver), or low (lower than the liver). RESULTS: The signal intensity of the 25 cysts, as determined by FLAIR-HASTE, was low in 21 cases (84%), intermediate in three (12%), and very high in one (4%), which was diagnosed as a complicated cyst in which ultrasound revealed internal septa. At FLAIR-HASTE, all 60 hemangiomas showed either very high (n=50, 83%) or moderately high (n=10, 17%) signal intensity, while that of 42 hepatic malignant tumors was very high in 14 cases (33%), moderately high in 8 (19%), slightly high in 18 (43%), intermediate in one (2.5%), and low in one (2.5%). CONCLUSION: FLAIR-HASTE showed that the signal intensity of the majority of hepatic cysts was low, while that of most hemangiomas and solid liver tumors was high. For the differentiatial diagnosis of cystic and non-cystic liver lesions, FLAIR-HASTE is an easily applicable MR imaging sequence.

Usefulness of Combined Fat- and Fluid-Suppressed SPIR-FLAIR Images in Optic Neuritis: Comparison with Fat-Suppressed SPIR or STIR Images or STIR images

PURPOSE: To compare the usefulness of combined fat- and fluid-suppressed selective partial inversion recovery-fluid attenuated inversion recovery(SPIR-FLAIR) images in the detection of high signal intensity of the optic nerve in optic neuritis with that of fat-suppressed selective partial inversion recovery(SPIR) or short inversion time inversion recovery(STIR) images. MATERIALS AND METHODS: Two radiologists independently analyzed randomly mixed MR images of 16 lesions in 14 patients (M:F=7:7; mean age, 40years) in whom optic neuritis had been clinically diagnosed. All subjects underwent both SPIR-FLAIR and fat-suppressed SPIR or STIR imaging, in a blind fashion. In order to evaluate the optic nerve, coronal images perpendicular to its long axis were obtained. The detection rate of high signal intensity of the optic nerve, the radiologists' preferred imaging sequences, and intersubject consistency of detection were evaluated. 'High signal intensity' was defined as the subjective visual evaluation of increased signal intensity compared with that of the contralateral optic nerve or that of white matter. RESULTS: The mean detection rate of high signal intensity of the optic nerve was 90% for combined fat- and fluid-suppressed SPIR-FLAIR images, and 59% for fat-suppressed SPIR or STIR images. In all cases in which the signal intensity observed on SPIR-FLAIR images was normal, that on fat-suppressed SPIR or STIR images was also normal. The radiologists preferred the contrast properties of SPIR-FLAIR to those of fat-suppressed SPIR or STIR images. CONCLUSION: In the diagnosis of optic neuritis using MRI, combined fat- and fluid-suppressed SPIR-FLAIR images were more useful for the detection of high signal intensity of the optic nerve than fat-suppressed SPIR or STIR images. For the evaluation of optic neuritis, combined fat- and fluid-suppressed SPIR-FLAIR imaging is superior to fat-suppressed SPIR or STIR imaging.

Evaluation of Chondromalacia in the Knee Joint using Three Dimensional Fourier Transformation Constructive Interference in Steady State(CISS)

PURPOSE: To assess the usefulness of three-dimensional Fourier transformation constructive interference in steady state (CISS) for the evaluation of chondromalacia. MATERIALS AND METHODS: In 110 knee joints which underwent both MR imaging and arthroscopy, the findings were retrospectively reviewed. MR imaging sequences included two-dimensional dual-echo turbo spin-echo imaging along the sagittal and coronal planes, two-dimensional fast low-angle shot (FLASH) with magnetization transfer along the axial plane, and three-dimensional CISS along the sagittal plane. After the cartilage surfaces of each joint were divided into eight areas (each medial and lateral area of patellar facets, trochlear surfaces, femoral condyles, and tibial plateaux), a total of 880 areas were assessed. Using both combined two-dimensional (2-D turbo spin-echo and FLASH) and CISS imaging during different sessions, each chondromalacia case was assigned one of five grades. RESULTS: Arthroscopy revealed the presence of chondromalacia in 162 areas. This was first grade in 77 areas, second grade in 38, third grade in 21, and fourth grade in 26. The sensitivity, specificity, and accuracy of 2-D and CISS imaging were 48.1%, 93.7% and 85.3%, and 45.7%, 95.3% and 86.1%, respectively. Agreement between MR and arthroscopic staging occurred in 81.48% of 2-D imaging procedures and 82.16% of CISS procedures. If a difference of one grade was accepted, these proportions rose to 84.32% and 85.22%, respectively, though this increase was statistically insignificant. CONCLUSION: Though CISS imaging was less sensitive than 2-D imaging in the grading of chondromalacia, additional CISS imaging can help improve the accuracy of this grading.

Fast Spin-Echo T2-Weighted MR Imaging of Tongue Cancer: the Value of Fat-suppression

PURPOSE: To compare the diagnostic efficacy of fast spin-echo (FSE) T2-weighted MR imaging with and without fat suppression. MATERIALS AND METHODS: Twelve patients (7 men and 5 women; mean age, 48 years) with pathologically proven cancer of the tongue were included in this study. In all of these, FSE T2-weighted MR images with and without fat suppression were obtained in the same imaging planes before surgery or biopsy. Two radiologists visually compared the images thus obtained in terms of detection, extent, and conspicuity of the tumor, and the contrast-to-noise ratio (CNR) of each tumor was also calculated. RESULTS: In all patients, both imaging modalities were equal in terms of tumor detection. In 4 of 12(33%), the extent of the tumor was greater with fat suppression, while in eight (67%), it was almost the same both with and without. In ten patients (83%), the tumor was more conspicuous with fat suppression, and percentage CNRs were significantly higher with fat suppression than without (180 +/-70% and 113 +/-61%, respectively; p = 0.02). CONCLUSION: For the evaluation of patients with tongue cancer, fat-suppressed FSE T2-weighted MR imaging is superior to its conventional equivalent.

Fast Spin-Echo T2-Weighted MR Imaging of Tongue Cancer: the Value of Fat-suppression

PURPOSE: To compare the diagnostic efficacy of fast spin-echo (FSE) T2-weighted MR imaging with and without fat suppression. MATERIALS AND METHODS: Twelve patients (7 men and 5 women; mean age, 48 years) with pathologically proven cancer of the tongue were included in this study. In all of these, FSE T2-weighted MR images with and without fat suppression were obtained in the same imaging planes before surgery or biopsy. Two radiologists visually compared the images thus obtained in terms of detection, extent, and conspicuity of the tumor, and the contrast-to-noise ratio (CNR) of each tumor was also calculated. RESULTS: In all patients, both imaging modalities were equal in terms of tumor detection. In 4 of 12(33%), the extent of the tumor was greater with fat suppression, while in eight (67%), it was almost the same both with and without. In ten patients (83%), the tumor was more conspicuous with fat suppression, and percentage CNRs were significantly higher with fat suppression than without (180 +/-70% and 113 +/-61%, respectively; p = 0.02). CONCLUSION: For the evaluation of patients with tongue cancer, fat-suppressed FSE T2-weighted MR imaging is superior to its conventional equivalent.

Comparison of Fast FLAIR and Echo-Planar FLAIR Imaging in Cere b ral Lesions

PURPOSE: To evaluate the usefulness of echo-planar FLAIR imaging in various cerebral lesions as compared with fast FLAIR imaging. MATERIALS AND METHODS: We obtained consecutive fast FLAIR and echo-planar FLAIR images in 33patients in whom MR imaging had revealed ischemic infarction (n=11), acute infarction (n=5), brain tumor (n=3), other conditions (n=3) or no abnormality (n=11). On both sets of images, percentage contrast and contrast to noise ratio (CNR) were calculated for white matter-gray matter and white matter-lesion. RESILTS: White matter-gray matter percentage contrast and CNR were lower on echo-planar FLAIR imaging than on fast FLAIR imaging (percentage contrast, 19 +/- 2 % vs 28 +/- 3 %, CNR, 2.77 +/- 0. 5 vs 4.86 +/- 0.7). White matter-lesion percentage contrast on echo-planar FLAIR imaging was similar to or greater than that on fast FLAIR imaging; 75 +/- 12 % vs 45 +/- 11 % in ischemic infarction, 80 +/- 12 % vs 78 +/- 11% in acute infarction, and 121 +/- 25 % vs 102 +/- 15 % for tumors. White matter-lesion CNR was similar on both sets of images: 8.3 +/- 0.9 vs 7.9 +/- 0.8 in ischemic infarction, 11 +/- 1.5 vs 9.5 +/- 1.2 in acute infarction, and 24 +/- 4 vs 27 +/- 3 for tumors. Due to high susceptibility to magnetization, echo-planar FLAIR imaging showed image degradation at the interface of the paranasal sinus and adjacent to the temporal bone. CONCLUSION: Echo-planar FLAIR imaging may be a useful pulse sequence in the diagnosis of various cerebral lesions.

Hyperacute Middle Cerebral Artery Territory Infarction: Comparison of Unenhanced CT, Spin-Echo T2-weighted,Fast FLAIR, and Diffusion-weighted MR Imaging

PURPOSE: To compare the detection rate of unenhanced CT, spin-echo T2-weighted, fast fluid-attenuatedin-version- recovery(FLAIR), and diffusion-weighted MR imaging in the diagnosis of hyperacute middle cerebralartery(MCA) territory infarction. MATERIALS AND METHODS: Sixteen patients with clinically proven hyperacute MCAterritory infarction were e-valuated with unenhanced CT and MR. All CT examinations were performed within sixhours of the onset of symptoms and all MR studies were performed within two hours of CT. All images were evaluatedindepen-dently by two radiologists in possession of brief clinical information. Positive imaging criteria wereparenchy-mal hypoattenuation, as seen on CT, and increased signal intensity, as seen on MR. For quantitativeanalysis, we measured the attenuation and signal intensity of the lesion and contralateral normal parenchyma, andper-centage contrast-to-noise ratios(CNRs) of the lesions were also calculated. RESULTS: Positive findings weredetected in all patients on diffusion-weighted images, in 13(81%) on CT, in 10 ( 63 %) on fast FLAIR images, andin 7(44 %) on T2-weighted images. Lesion percentage CNRs were 30% for diffusion-weighted imaging, 15 % for CT, 18% for FLAIR MR imaging, and 16 % for T2-weighted MR imag-ing(p < .004 for diffusion-weighted imaging vs others). CONCLUSION: For hyperacute MCA territory infarction, diffusion-weighted MR imaging was the most sensitive imagingtechnique and unenhanced CT was superior to fast FLAIR or T2-weighted imaging.

Utility of Dual Echo T2-Weighted Turbo Spin Echo MR Imaging for Differentiation of Solid, Malignant HepaticLesions from Nonsolid, Benign Hepatic Lesions

PURPOSE: To evaluate the additive value of multiphasic contrast-enhanced dynamic MR imaging as a supple-mentto dual-echo T2-weighted TSE MR imaging for the differentiation of solid, malignant hepatic lesions from nonsolid,benign hepatic lesions. MATERIALS AND METHODS: Two radiologists retrospectively reviewed dual-echo T2-weightedTSE MR images and gadolinium-enhanced MR images in 51 patients with hepatic lesions (28 malignant, 69 benign). Forthe dif-ferentiation of malignant from benign lesions, as seen on dual-echo T2-weighted TSE MR images, weevaluated sensitivity, specificity, and accuracy, and compared with the results with those for dual echoT2-weighted MR images plus multiphasic contrast-enhanced dynamic MR images. In addition, Az values for dual echoT2-weighted MR images were compared with those for dual echo T2-weighted MR images plus multiphasiccon-trast-enhanced dynamic MR images. RESULTS: For the differentiation of malignant from benign hepatic lesions,as seen on dual-echo T2-weighted TSE images, sensitivity, specificity, and accuracy were 80.0 %, 97.5 %, and 93.9%, respectively, for lesions less than 3 cm in diameter, and 92.3 %, 95.0 %, and 93.5 %, respectively, for thosethat were 3 cm or larger. The results for dual-echo T2-weighted MR imaging plus multiphasic contrast-enhanceddynamic MR imaging were 86.7%, 100.0%, and 97.3%, respectively, for lesions less than 3 cm, and 92.3%, 100.0 %,and 95.7 %, re-spectively for those that were 3 cm or larger. There were no significant differences insensitivity, specificity, or accuracy between the results obtained using dual-echo T2-weighted MR imaging andthose obtained with d-ual- echo T2-weighted MR imaging plus multiphasic contrast-enhanced dynamic MR imaging. Norwere there statistically significant differences in Az values between the two groups. CONCLUSIONS: For thedifferentiation of solid, malignant hepatic lesions from nonsolid, benign hepatic lesions, there is no differencein accuracy between dual-echo T2-weighted TSE MR imaging and the additional use of multiphasic contrast-enhancedMR imaging. Dual-echo T2-weighted TSE MR imaging may, therefore, be use-ful for the differentiation of solid,malignant hepatic lesions from nonsolid, benign hepatic lesions without the use of multiphasic contrast-enhancedMR imaging.

The Value of True FISP Sequence as a Fast T2-Weighted MR Imaging of Liver: Comparison with Breath-hold Turbo Spin Echo and HASTE Sequence

PURPOSE: To document the relative usefulness of true Fast-imaging steady-state precession(FISP) comparing to breath-hold turbo spin-echo(TSE), and half-Fourier single-shot turbo spin-echo(HASTE) as a fast T2-weighted sequence during hepatic MR imaging. MATERIALS AND METHODS: For 46 patients with 87 focal hepatic lesions(hepatocellular carcinoma, n=26; metastasis. n=5; cavernous hemangioma, n=37; cyst, n=19), we obtained MR imaging of the liver at 1.5T. True FISP, TSE with and without fat-suppresion(FS), and HASTE with and without FS images were obtained during one breath-hold. Images were compared on the basis of tumor detectability and lesion-to-liver contrast-to-noise ratio(CNR). Qualitative analysis of each imaging sequence was also performed in terms of hepatic contour, visibility of vascular landmarks and imaging artifacts. RESULTS: TSE-FS depicted more focal lesions(78/87, 90%) than other sequences(TSE, 75/87=86%;HASTE, 74/87=85%; HASTE-FS, 75/87=86%;true FISP,73/87=84%). However, there was no statistical significance between each sequence(p> .05). Using true FISP or HASTE, there was a statistically significant difference(p< .01) between the CNRs of solid tumors, crystal and hemangiomas. Additionally, true FISP sequence showed better hepatic contour, vascular landmarks and less artifacts comparing with TSE or HASTE regardless of FS(p< .001). CONCLUSION: True FISP sequence allows differentiation between solid tumors, hemangiomas and cystic lesions in terms of CNR, and provides better imaging quality than other fast T2-weighted MR sequences.

Usefulness of Fluid Attenuated Inve rsion Re c overy(FLAIR) Image

PURPOSE: To determine the usefulness of fluid attenuated inversion recovery(FLAIR) imaging for the in detection of high signal intensity of hippocampus or amygdala in mesial temporal sclerosis (MTS), compared with that of turbo spin-echo T2-weighted imaging. MATERIALS AND METHODS: Two neuroradiologists independently analyzed randomly mixed MR images of 20 lesions of 17 patients in whom MTS had been diagnosed, and ten normal controls. All subjects underwent both who performed both FLAIR and turbo spin-echo T2-weighted imaging, in a blind fashion. In order to determine hippocampal morphology, oblique coronal images perpendicular to the long axis of the hippocampus were obtained. The detection rate of high signal intensity in hippocampus or amygdala, the radiologists 'preferred imaging sequence, and intersubject consistency of detection were evaluated. Signal intensity in hippocampus or amygdala was considered high if substantially higher than signal intensity in the cortex of adjacent temporo-parietal lobe. RESULTS: In all normal controls, FLAIR and spin-echo T2-weighted images showed normal signal intensity in hippocampus or amygdala. In MTS, the mean detection rate of high signal intensity in hippocampus or amyg-dala, as seen on FLAIR images was 93%, compared with 43% on spin-echo T2-weighted images. In all cases in which signal intensity on FLAIR images was normal, signal intensity on spin-echo T2-weighted images was also normal. The radiologists preferred the contrast properties of FLAIR to those of spin-echo T2-weighted images. CONCLUSION: In the diagnosis of MTS using MRI, FLAIR images are more useful for the detection of high signal intensity of hippocampus or amygdala than are spin-echo T2-weighted images. In the diagnosis of MTS, FLAIR imaging is therefore a suitable alternative to spin-echo T2-weighted imaging.