T2-weighted breath-hold MRI of the liver at 1.0 T: comparison of turbo spin-echo and HASTE sequences with and without fat suppression

To compare the clinical usefulness of T2-weighted breath-hold sequences for imaging the liver, 33 patients with 97 focal hepatic lesions were studied with a 1.0-T scanner by using T2-weighted breath-hold turbo spin-echo (SE) sequences and T2-weighted breath-hold half-Fourier single-shot turbo SE (HASTE) sequences with and without fat suppression. Images were quantitatively analyzed for liver signal-to-noise ratio (SNR) and lesion-to-liver contrast-to-noise ratios (CNR). Qualitative analysis was performed for lesion conspicuity, motion artifacts, and anatomic sharpness of extrahepatic structures. Breath-hold turbo SE imaging with fat suppression showed the highest CNR for cystic lesions and the best lesion conspicuity for cystic and solid lesions among the four sequences. For solid lesions, there was no significant difference of lesion-to-liver CNR between them. HASTE sequence was superior to turbo SE sequences in terms of motion artifacts; however, the usefulness for evaluating focal hepatic lesions was limited compared with turbo SE sequence with fat suppression. Addition of fat suppression was not helpful for HASTE imaging because of decreased lesion conspicuity and extrahepatic details without the advantage of reducing motion artifacts. This study suggests that turbo SE sequence with fat suppression is most useful for breath-hold T2-weighted liver imaging at 1.0 T. Addition of imaging without fat suppression can be considered for evaluating extrahepatic structures. HASTE sequence may have a role for imaging uncooperative patients due to absence of motion artifacts.     

Fast spin-echo MR imaging of the eye

Magnetic resonance imaging of the eye usually includes T2-weighted images both for screening purposes and for characterization of melanoma. Conventional T2-weighted spin-echo (SE) imaging suffers both from long acquisition times and incomplete recovery of the vitreous' signal. A fast SE sequence was therefore compared prospectively with conventional sequences in 29 consecutive patients with lesions of the eye. Fast SE images delineated melanoma and other lesions of the eye from vitreous better than conventional T2-weighted images. Image quality and lesion conspicuity were improved on the fast sequence. Whereas melanoma appeared hypointense to vitreous on both types of images, subretinal effusion was hypointense on fast images and hyperintense on conventional T2-weighted images. Ghosting of the globe, which, however, did not decrease diagnostic value, was more pronounced on fast images. Conventional T2-weighted images may be replaced by fast SE images in MR studies of the eye with a gain in lesion conspicuity and significant time saving.     

Non-breath-hold fast spin-echo versus breath-hold fast spin-echo and spoiled gradient-recalled echo MR imaging in the detection of hepatic tumors: correlation with surgical findings

OBJECTIVE: Our objective was to compare the sensitivity of non-breath-hold T2-weighted fast spin-echo with and without fat suppression, breath-hold T2-weighted fast spin-echo without fat suppression, and spoiled gradient-recalled echo (GRE) MR imaging for detecting hepatic tumors using surgical findings as the standard of reference. SUBJECTS AND METHODS: Eighteen patients with 36 surgically proven hepatic tumors had non-breath-hold T2-weighted fast spin-echo (6000/117 [TR/effective TE; echo train length, 16) MR imaging with and without fat suppression, breath-hold T2-weighted fast spin-echo MR imaging (2700/105; echo train length, 20), and spoiled GRE images (10.1/1.9; flip angle, 30 degrees) obtained before and after injection of a gadolinium chelate. Images were analyzed separately by two independent readers, with disagreements resolved by consensus reading. RESULTS: Non-breath-hold T2-weighted fast spin-echo MR imaging with and without fat suppression depicted 22 (61%; 95% confidence interval [CI], 43-77%) and 20 (56%; 95% CI, 37-72%) of 36 hepatic tumors, respectively. Breath-hold T2-weighted fast spin-echo imaging allowed detection of 19 (53%; 95% CI, 35-69%) of 36 hepatic tumors. Unenhanced and gadolinium chelate-enhanced spoiled GRE images allowed depiction of 18 (50%; 95% CI, 33-67%) and 29 (81%; 95% CI, 63-91%) of 36 hepatic tumors, respectively. Gadolinium chelate-enhanced spoiled GRE images allowed depiction of significantly more hepatic tumors than any of the other pulse sequences. CONCLUSION: Gadolinium chelate-enhanced spoiled GRE imaging is more sensitive than T2-weighted MR imaging obtained with a breath-hold or a non-breath-hold technique.     

Preoperative staging of endometrial carcinoma: diagnostic effect of T2-weighted fast spin-echo MR imaging

PURPOSE: To evaluate the usefulness of T2-weighted fast spin-echo magnetic resonance (MR) imaging with a 512 x 256 matrix for assessment of the preoperative stage of endometrial carcinoma. MATERIALS AND METHODS: Twenty-eight women with histopathologically proved endometrial carcinoma underwent preoperative T2-weighted fast spin-echo, dynamic T1-weighted fast spin-echo, and postcontrast T1-weighted spin-echo MR imaging with a phased-array surface coil. The uterine long-axis planes in each sequence were reviewed at separate sessions by three radiologists blinded to the histopathologic data. RESULTS: For the diagnosis of myometrial invasion, no statistically significant differences were found among T2-weighted imaging, dynamic imaging, and postcontrast T1-weighted imaging. For the diagnosis of deep myometrial invasion, T2-weighted and dynamic images showed higher specificity than postcontrast T1-weighted images (T2-weighted, 89%; dynamic, 88%; and postcontrast T1-weighted, 80%). For cervical invasion, T2-weighted and dynamic images showed larger areas under receiver operating characteristic curves than did postcontrast T1-weighted images (T2-weighted, 0.78; dynamic, 0.71; and postcontrast T1-weighted, 0.67). CONCLUSION: T2-weighted imaging is useful for identifying the stage of endometrial carcinoma.     

T2-weighted spin-echo MR imaging of the liver: breath-hold fast spin-echo versus non-breath-hold fast spin-echo images with and without fat suppression

OBJECTIVE: The goal of our study was to compare a T2-weighted breath-hold fast spin-echo (BHSE) technique with T2-weighted non-breath-hold fast spin-echo techniques for imaging the liver. SUBJECTS AND METHODS: Thirty-three patients with hepatic lesions had T2-weighted BHSE images obtained in 22 sec and conventional T2-weighted non-breath-hold fast spin-echo images obtained in 3 min 12 sec with and without fat suppression. Images were analyzed quantitatively by measuring the lesion-liver contrast, spleen-liver contrast, and signal-to-noise ratios of lesions and qualitatively by evaluating the sharpness of hepatic contours, visibility of intrahepatic vessels and other segmental landmarks, and presence of artifacts. RESULTS: Quantitatively, lesion-liver contrast, spleen-liver contrast, and signal-to-noise ratios obtained with the BHSE technique were inferior to those obtained with fast spin-echo techniques with and without fat suppression (11.2 +/- 7.1 versus 15.4 +/- 10.6 and 14.5 +/- 9.8, p < .001; 5.3 +/- 3.7 versus 8.7 +/- 3.5 and 7.0 +/- 3.8, p < .001; 16.2 +/- 8.2 versus 20.1 +/- 10.9 and 19.7 +/- 9.5, p < .01, respectively; Student's t test). Qualitatively, image artifacts and intrahepatic vessel depiction on BHSE images were similar to those obtained with the fast spin-echo techniques. The BHSE technique was superior to fat-suppressed fast spin-echo technique for showing hepatic contours (p < .01; Wilcoxon signed-rank test). CONCLUSION: The BHSE technique is quantitatively inferior to non-breath-hold fast spin-echo techniques. However, further studies with a surgical standard of reference are needed to compare the three techniques in terms of sensitivity.     

High-resolution MRI of pancreatic masses with a new circularly polarized body phased-array coil

A total of 18 patients with clinical suspicion of a pancreatic tumor underwent dynamic contrast-enhanced CT and MRI examinations. A fat-suppressed T1-weighted 2D fast-low-angle-shot (FLASH) sequence and a T2-weighted spin-echo (SE) sequence were applied in a transverse orientation using a circularly polarized (CP) body phased-array coil. The FLASH sequence was repeated after Gd-DTPA administration. The highest spatial resolution was 1.37 x 1.37 x 3.00 mm3. In two cases a half Fourier single-shot turbo-SE sequence (HASTE) was additionally applied. In a comparison between CT and MRI, pancreatic masses could be demonstrated and characterized with excellent image quality. The fat-saturated 2D FLASH sequence yielded the highest contrast-to-noise ratios after Gd-DTPA administration between pancreas and inflammatory or neoplastic lesion. One non-contour deforming carcinoma could be detected only with MRI and was only retrospectively visible on CT with an element of uncertainty. Magnetic resonance imaging using a CP body phased-array coil and fat-suppressed T1- and T2-weighted FLASH, SE, and turbo-SE sequences offers diagnostic possibilities in improved imaging of the pancreas.     

Hepatic cavernous hemangioma: appearance on T2-weighted fast spin-echo MR imaging with and without fat suppression

OBJECTIVE: The goals of our study were to define the morphologic appearance of cavernous hemangioma of the liver on T2-weighted fast spin-echo MR imaging and to determine if the use of fat suppression may quantitatively and qualitatively modify the MR imaging appearance of cavernous hemangioma. SUBJECTS AND METHODS: Twenty-six patients with cavernous hemangiomas of the liver were prospectively studied with T2-weighted MR imaging with a fast spin-echo technique with and without fat suppression. Thirteen patients had known hemangiomas for more than 2 years, with no change in size or morphology during this period. The remaining 13 patients had diagnoses based on dynamic CT and sonography and an absence of change in the morphology and size of their lesions during follow-up of more than 6 months (range, 6-12 months) after the MR imaging studies. Values for signal intensity and contrast-to-noise (C/N) ratios in cavernous hemangiomas that were obtained with and without fat suppression were compared. Images were qualitatively analyzed separately at identical level and window settings by two interpreters for morphologic features of cavernous hemangiomas. RESULTS: No significant difference was found between signal intensity values obtained using the fat-suppressed fast spin-echo MR imaging technique (5.62 +/- 1.14 [SD]) and those obtained without fat suppression (5.51 +/- 1.23). Values for C/N ratios obtained with the fat-suppressed fast spin-echo MR imaging technique (20.13 +/- 7.63) were significantly superior to those obtained without fat suppression (16.59 +/- 5.31) (p < .001). On T2-weighted fast spin-echo MR imaging without fat suppression, 100% of cavernous hemangiomas were hyperintense relative to the spleen, 90% had well-defined and sharp margins, 55% were isointense to CSF, and 76% were homogeneous. Without fat suppression, 34% of cavernous hemangiomas showed the combination of isointensity to CSF, well-defined margins, and homogeneity. On T2-weighted fast spin-echo MR imaging with fat suppression, all cavernous hemangiomas showed this same combination of features. CONCLUSION: Seventy-six percent of hepatic cavernous hemangiomas were homogeneous on T2-weighted fast spin-echo MR imaging, and 55% were isointense to CSF. However, only 34% of hepatic cavernous hemangiomas showed typical features. Although fat suppression significantly increased the C/N ratio of cavernous hemangiomas of the liver, fat suppression did not affect their morphologic appearance on T2-weighted fast spin-echo MR imaging.     

Fat-suppressing STIR sequences with and without contrast media in the MRT of ENT tumors

Fat-suppressed STIR (short TI inversion recovery) sequences were compared to plain and contrast-enhanced T1-weighted SE sequences of head and neck tumors. 19 patients underwent MR imaging on a 0.5 Telsa system (T5-II, Philips). STIR imaging parameters: TR/TE = 1000/20 ms, inversion pulse 100 ms. All films were read by four radiologists. The image quality was graded: score from 0 to 5, by means that grade 5 = optimal quality. Sensitivity was 89% in STIR, 96% in SE sequences. Tumor delineation was graded good in the enhanced T1-weighted and enhanced fat suppression images. The unenhanced imaging was superior in STIR (STIR/T1 = 2.8/2.43). The tumor contrast was best in contrast enhanced and plain STIR sequences (STIR contrast = 3.41), and in the contrast enhanced T1-weighted SE (3.33). STIR almost equaled T1 post-contrast in respect of tumour conspicuity, but the sensitivity was lower. STIR can be a supplement to SE, but cannot substitute T1 postcontrast. The combined use is expected to have the highest assessment value.     

Modifications in the rhythm of schizogony in Plasmodium chabaudi chabaudi associated with the selection of chloroquine resistance

Thirty-two patients affected with skeletal conditions were examined with MRI using Short TI Inversion Recovery sequence and Spectral Presaturation with Inversion Recovery (SPIR) sequence as well as Spin-Echo (SE) T1-weighted sequence and Fast Spin-Echo (FSE) T2-weighted sequence to compare their value in the assessment of skeletal lesions. SPIR sequence was performed after intravenous injection of Gd-DTPA. The lesions included primary bone tumors (10 cases: 1 osteosarcoma, 1 periosteal sarcoma, 1 Ewing's sarcoma, 1 chondrosarcoma, 2 non-ossifying fibromas, 1 chondroma, 1 chondromyxoid fibroma, 1 desmoplastic fibroma and 1 bone cyst), metastases (7 cases: 3 prostate, 3 breast, 1 lung-squamous cell carcinoma), infections (12 cases: 9 osteomyelitis, 3 spondylodiscitis), sacroiliitis (1 case) and posttraumatic bone bruise (2 cases of bone marrow edema). The four sequences were compared by using both qualitative and quantitative evaluation. Qualitative evaluation showed that STIR sequence was better than SPIR sequence (performed with Gd-DTPA) for lesion conspicuity (p < .016) and for signal intensity uniformity (p < .03). Compared with SE T1 and FSE T2 sequences, fat-suppressed sequences were superior for conspicuity, margins, and extension of the lesions (range of p < .001-.017). Only SPIR with Gd-DTPA sequence, compared with SE T1 sequence for lesion conspicuity was not statistically significantly different. Quantitative evaluation showed statistically significant higher values of percent contrast (%C) and contrast-to-noise ratio (C/N) for STIR sequence compared with SPIR sequence (%C p < .004; C/N p < .040). This study suggests that STIR sequence and SE T1-weighted sequence provide high sensitivity in lesion detection and good anatomical definition. The use of a fat-suppressed sequence with Gd-DTPA can be useful for lesion characterization.     

Fast fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging of the brain: a comparison of multi-shot echo-planar and fast spin-echo techniques

PURPOSE: To evaluate fast spin-echo and multi-shot echo-planar fluid-attenuated inversion recovery (FLAIR) sequences in paediatric brain imaging. MATERIALS AND METHODS: Matched images from 32 patients with suspected tumour or white matter disease were independently evaluated by two paediatric neuroradiologists. The observer preferences for image quality and lesion detection were analysed for differences between fast spin-echo FLAIR and multi-shot echo-planar FLAIR. Diagnostic quality was compared with that of fast spin-echo T2-weighted images. RESULTS: Images of a diagnostic quality equivalent to that of fast spin-echo T2-weighted images were achieved with both FLAIR techniques. Grey and white matter differentiation and cerebrospinal fluid (CSF) nulling were significantly better on fast spin-echo FLAIR sequences. CSF flow artefact was reduced on multi-shot echo-planar FLAIR. There was no difference in lesion detection. Fast spin-echo FLAIR images were visually preferred at the expense of longer imaging time. CONCLUSION: Fast FLAIR techniques are complementary to fast spin-echo T2-weighted sequences in imaging of the paediatric brain. We find that the fast spin-echo FLAIR sequence is preferable to the multi-shot echo-planar technique.     

Effects of feeding on protein turnover in healthy children and in children with cystic fibrosis

In 24 patients presenting with 55 renal lesions (mean size, 20.8 mm), single-breath-hold (SBH) fast spin-echo (FSE) techniques allowing T1 and T2 images to be produced within 20 and 23 sec, respectively, were compared with routine non-breath-hold (NBH) spin-echo (SE) T1 and NBH-FSE T2 sequences. Contrast-to-noise ratios (CNRs) measured from SBH-FSE T1 images were an average of 97% higher than their NBH counterparts (P = .0001) and allowed an improved lesion conspicuity in 80% of the cases (P = 0.0001). For T2 imaging, SBH-FSE and NBH-FSE sequences were not statistically different with respect to lesion conspicuity (P = .55) and CNR values (P = .19). This was observed despite a 35% average decrease in CNR of SBH-FSE compared to NBH-FSE images. By reducing respiratory motion artifacts while preserving SE-like image contrast, SBH-FSE techniques have the potential to replace routine NBH sequences for an optimal diagnosis of renal masses.     

Hepatic T2-weighted MRI: a prospective comparison of sequences, including breath-hold, half-Fourier turbo spin echo (HASTE)

The purpose of this study was to quantitatively compare the hepatic contrast characteristics of conventional spin-echo (CSE) and fast spin-echo (FSE) sequences with breath-hold T2-weighted images acquired with half-Fourier turbo spin echo (HASTE). Forty-five patients were examined with a phased-array surface coil. Nineteen patients had focal hepatic lesions, including eight malignant tumors, 10 cavernous hemangiomas, and one hepatic adenoma. Twenty-six patients had no focal hepatic lesions. T2-weighted images with comparable TE were acquired with CSE, FSE, and HASTE pulse sequences. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) for liver, spleen, and lesions were measured. FSE demonstrated significantly better quantitative performance than CSE for liver-spleen CNR (P .0084). No statistically significant difference was demonstrated between FSE and CSE for liver or spleen SNR. FSE demonstrated clear scan time and resolution advantages over CSE. HASTE performed significantly poorer than CSE and FSE for liver-spleen CNR (P < .0001), liver SNR (P = .0002 for CSE and P < .0001 for FSE), and spleen SNR (P < .0001). Optimized FSE images with a short echo train length performed comparably to CSE images of equivalent TE. Liver-lesion CNR was suppressed on HASTE images, suggesting that long echo train length FSE sequences could diminish solid lesion detection compared to CSE and short echo train length FSE.     

MR imaging of the anterior cruciate ligament: frequency of discordant findings on sagittal-oblique images and correlation with arthroscopic findings

OBJECTIVE: The purposes of this study were to determine the frequency of discordant MR findings of the anterior cruciate ligament (ACL) using sagittal-oblique images and the arthroscopic integrity of the ACL in knees with a discordant MR appearance. MATERIALS AND METHODS: The frequency of discordant MR features was determined by independently reviewing the sagittal-oblique images of 53 consecutive patients undergoing subsequent arthroscopic surgery. The first 25 consecutive knees were examined using a conventional, dual-echo, T2-weighted spin-echo (SE) sequence; the subsequent 28 consecutive knees were examined using both a T1-weighted SE(T1) and a fat-suppressed, fast spin-echo (FSE) T2-weighted sequence. Two examiners who were unaware of patient identification and arthroscopic results evaluated only the sagittal images that included the ACL. Each reviewer graded the ACL as torn or intact. The MR appearance was considered discordant when one MR sequence showed disrupted or poorly seen ACL fibers and the other sequence showed intact ACL fibers. The arthroscopic integrity of the ACL was determined for the 20 knees with a discordant MR appearance. RESULTS: A discordant MR appearance of the ACL was seen in 20 of the 53 knees (38%), including 10 knees evaluated using conventional T2-weighted sequences (40%) and 10 knees using T1/FSE T2 (36%) sequences. Arthroscopic examination of these knees showed intact ACL fibers in all 20 knees; the ACL was normal in 18 knees and a partial tear was questioned in two knees. CONCLUSION: A discordant appearance of the ACL was frequently encountered (38%) using either conventional T2-weighted sequences or T1 and FSE MR sequences in the sagittal-oblique plane. Intact ACL fibers were found during arthroscopy in all 20 knees with a discordant MR appearance.     

Enhancement efficacy of magnetic starch microshperes (MSM) in conventional spin-echo and turbo spin-echo sequences at 0.5 T and 1.5 T

The efficacy of the superparamagnetic contrast agent magnetic starch microspheres (MSM) was evaluated in vitro by NMR relaxometry and in vivo by MR imaging using T2-weighted spin-echo (SE) and turbo spin-echo (TSE) sequences at 0.5 T and 1.5 T in 60 normal rats who received MSM in doses of 10-50 mu mol/kg. MR imaging was performed using T2-weighted SE and TSE sequences. The relaxation rates 1/T1 and 1/T2 for liver and spleen increased linearly with MSM concentrations up to 30 mu mol/kg body weight, and approached almost constant levels for higher doses. The slopes in the linear part of the 1/T2 diagram were 0.62 Hz +/- 0.03 for the liver and 0.51 Hz +/- 0.06 x kg/mu mol for the spleen. On all T2-weighted sequences at 0.5 T and 1.5 T, liver signal-to-noise ratio (SNR) decreased by a factor of 2-3 already at the lowest dose of 10 mu mol/kg. SNR values of TSE sequences exceeded values for SE sequences by 50-80%. The SNR decrease was not significantly different between SE and TSE sequences. Our results show that MSM is well suited as a T2 contrast agent at both magnetic field strengths when using conventional SE and fast TSE sequences.     

Multishot echoplanar MR imaging of the female pelvis: comparison with fast spin-echo MR imaging in an initial clinical trial

OBJECTIVE: The purpose of this study was to apply multishot echoplanar MR imaging (EPI) to the female pelvis and compare image quality with that of fast spin-echo MR imaging. SUBJECTS AND METHODS: Twenty-one patients with suspected pelvic disease and five healthy female volunteers were prospectively examined. MR imaging was obtained using an EPI-capable 1.0-T imager and a pelvic phased-array coil. Axial EPI and fast Spin-echo sequences were obtained at identical image locations in each patient and volunteer. Spin-echo EPI images were obtained using a multishot number of 16. Acquisition time for each EPI sequence was 2 min 10 sec. Fat-suppressed T2-weighted fast spin-echo images were obtained in 2 min 12 sec. Paired EPI and fast spin-echo MR images were independently evaluated by three reviewers. RESULTS: Delineation of the perivaginal and parametrial venous plexus on EPI was rated superior to the fast spin-echo images in 62 (77%) of 81 cases. On EPI, uterine zone anatomy and ovary visualization were judged to be inferior in 44 (56%) of 78 cases and in 18 (33%) of 54 cases, respectively. For delineation of uterine abnormalities, including leiomyoma and adenomyosis, both sequences performed almost equally well. However, ovarian cystic lesions were revealed more precisely by the fast spin-echo sequence. An overall fat-suppression effect was seen on EPI images in 62 (77%) of 81 cases. CONCLUSION: Multishot EPI cannot replace fast spin-echo sequences for imaging the female pelvis; however, because EPI has a potent fat-suppression effect and heavily T2-weighted contrast, EPI sequences can be a valuable adjunct to routine examination.     

Macroscopic tumor volume of malignant glioma determined by contrast-enhanced magnetic resonance imaging with and without magnetization transfer contrast

The purposes of this study were to compare the conspicuity and lesion volume of contrast-enhancing macroscopic malignant glioma determined by postcontrast magnetic resonance (MR) imaging with and without magnetization transfer (MT) saturation, and to discuss possible implications for radiotherapy planning. Nineteen patients (age 24-60 years) with histologically proven malignant glioma were prospectively examined by MR imaging. After the administration of gadolinium dimeglumine (0.1 mmol/kg body weight), the lesions were imaged with an MT-weighted FLASH (fast, low-angle shot) pulse sequence and with a conventional T1-weighted spin-echo (SE) sequence without MT saturation. The mean tumor volumes of gliomas measured on MT-weighted FLASH images were significantly (p < .01) larger than those obtained from T1-weighted SE images (45 +/- 15 cm3 vs. 33 +/- 10 cm3). The mean contrast-to-noise ratio of enhancing lesions on MT-weighted FLASH was 48 +/- 14 compared with 30 +/- 14 on SE images, representing a significant (p < .01) improvement. We conclude that the volume of contrast enhancement of malignant glioma identified on MT-weighted FLASH images represents the area of disrupted blood-brain barrier. If this volume of subtle contrast enhancement is caused by tumor infiltration and represents the boost target volume for stereotactic radiosurgery or brachytherapy, MT-weighted FLASH images would be better than T1-weighted SE images to define these volumes. These improved delineation of areas at highest risk for recurrence following radiation therapy should enhance the efficacy of treatment planning for high-boost therapy.     

Four new mutations in the apolipoprotein B gene causing hypobetalipoproteinemia, including two different frameshift mutations that yield truncated apolipoprotein B proteins of identical length

Magnetic resonance imaging is frequently complicated by the presence of motion and susceptibility gradients. Also, some biologic tissues have short T2s. These problems are particularly troublesome in fast spin-echo (FSE) imaging, in which T2 decay and motion between echoes result in image blurring and ghost artifacts. The authors reduced TE in conventional spin-echo (SE) imaging to 5 msec and echo spacing (E-space) in FSE imaging to 6 msec. All magnetic gradients (except readout) were kept at a maximum, with data sampling as fast as 125 kHz and only ramp waveforms used. Truncated sinc radio-frequency pulses and asymmetric echo sampling were also used in SE imaging. Short TE (5.8 msec) SE images of the upper abdomen were compared with conventional SE images (TE = 11 msec). Also, FSE images with short E-space were compared with conventional FSE images in multiple body sites. Short TE significantly improved the liver-spleen contrast-to-total noise ratio (C/N) (7.9 vs 4.1, n = 9, P < .01) on T1-weighted SE images, reduced the intensity of ghost artifacts (by 34%, P < .02), and increased the number of available imaging planes by 30%. It also improved delineation of cranial nerves and reduced susceptibility artifacts. On short E-space FSE images, spine, lung, upper abdomen, and musculoskeletal tissues appeared crisper and measured spleen-liver C/N increased significantly (6.9 vs 4.0, n = 12, P < .01). The delineation of tissues with short T2 (eg, cartilage) and motion artifact suppression were also improved. Short TE methods can improve image quality in both SE and FSE imaging and merit further clinical evaluation.     

Magnetic resonance imaging of fistula-in-ano: STIR or SPIR?

Patients with clinically suspected anorectal sepsis were studied using MRI in order to determine if T2 weighted sequences with fat suppression conveyed any additional benefit over conventional short tau inversion recovery (STIR) sequences. 23 consecutive patients (16 male) undergoing MRI for suspected perianal sepsis were studied prospectively using a 1.0 T whole body system and body coil. Axial and coronal T1 weighted turbo spin echo sequences were obtained, followed by STIR and T2 weighted spectral fat saturation inversion recovery (SPIR) sequences. Images were assessed for the presence of sepsis or fistula, and information provided by the sequences compared. Active disease was diagnosed in 17 patients, 14 of whom had fistula-in-ano; one intersphincteric, 10 transsphincteric and three extrasphincteric. Internal openings were identified in all of these 14 patients; anal in 10, rectal in two, and both in two. Diagnosis and fistula classification was possible in all of these 14 subjects on the basis of STIR sequences alone. The anal sphincters and pelvic floor musculature were better resolved by STIR than SPIR, leading to easier and more confident determination of fistula anatomy in eight of the 14 (57%). In no case did STIR sequences fail to resolve inflammation seen subsequently on SPIR, despite reduced track intensity. T1 weighted sequences were generally non-contributory. Both STIR and SPIR sequences are adequate to classify fistula-in-ano, but classification was easier with STIR due to superior resolution of pelvic floor structures.     

Chronic pulmonary histoplasmosis in Brazil: report of two cases with cavitation diagnosed by transthoracic needle biopsy

OBJECTIVE: To compare fat-suppressed fast spin-echo (FSE) T2-weighted images with gradient-recalled echo (GRE) T2*-weighted images in the evaluation of anteroinferior labral tears. DESIGN: MR images were retrospectively reviewed by two radiologists masked to the history and arthroscopic findings. They separately interpreted the anteroinferior labrum as torn or intact, first on one pulse sequence and then, 4 weeks later, on the other sequence. The MR interpretations were correlated with the arthroscopic findings. PATIENTS: Nine patients with anteroinferior labral tears, and nine similarly-aged patients with normal, labra were studied. RESULTS AND CONCLUSIONS: Observer 1 had a sensitivity of 0.56 on the GRE images and 0.67 on the FSE images (P > 0.5), with a specificity of 1.0 for both sequences. Observer 2 had a sensitivity of 0.78 and a specificity of 0.89 for both sequences. In this small study there is no significant difference between GRE and fat-suppressed FSE images in their ability to diagnose anteroinferior labral tears. When evaluating the labrum with conventional MRI, axial fat-suppressed FSE T2-weighted images can be used in place of GRE images without a loss of accuracy.     

Fast fluid-attenuated inversion-recovery (FLAIR) MRI in the assessment of intraaxial brain tumors

This study demonstrates the value of a fast fluid-attenuated inversion-recovery (FLAIR) technique in the assessment of primary intraaxial brain tumors. Twenty-one patients with primary intraaxial brain tumors were examined by T2-weighted, proton-density-weighted fast spin echo, fast FLAIR, and contrast-enhanced T1-weighted spin echo using identical slice parameters. The images were evaluated using quantitative and qualitative criteria. Quantitative criteria were tumor-to-background and tumor-to-cerebrospinal fluid (CSF) contrast and contrast-to-noise ratio (CNR). The qualitative evaluation was performed as a multireader analysis concerning lesion detection, lesion delineation, and image artifacts. In the qualitative evaluation, all readers found the fast FLAIR to be superior to fast spin echo in the exact delineation of intraaxial brain tumors (P < .001) and the delineation of enhancing and nonenhancing tumor parts. Fast FLAIR was superior in the delineation of cortically located and small lesions but was limited in lesions adjacent to the ventricles. Fast FLAIR provided a significantly better tumor-to-CSF contrast and tumor-to-CSF CNR (P < .001). The tumor-to-background contrast and tumor-to-background CNR of the fast FLAIR images were lower than those of T2-weighted spin-echo images but higher than those of proton-density-weighted spin-echo images. FLAIR images had more image artifacts influencing the image interpretation in only two patients. Signal hyperintensities at the ventricular border were present in 92% of the patients. They are common findings in fast FLAIR and should be included into the image interpretation.