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PubMed1997

Magnetic resonance imaging with fluid-attenuated inversion recovery pulse sequences in MELAS syndrome.

We report the brain magnetic resonance imaging findings in the case of a 5-year-old boy with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS). Fluid-attenuation inversion recovery (FLAIR) imaging revealed multifocal abnormal cortical signals which were difficult to see on conventional T1- and T2-weighted images. Although the patient was in an advanced clinical stage of disease and had severe cortical atrophy, FLAIR imaging demonstrated characteristic findings of MELAS.

Atrophy↗
PubMedDate not supplied

MR of the brain using fluid-attenuated inversion recovery (FLAIR) pulse sequences.

PURPOSE: Results from conventional T2-weighted spin-echo sequences were compared with those obtained using fluid attenuated inversion recovery (FLAIR) pulse sequences in order to assess their relative merits in detecting disease. METHODS: Forty adult patients with suspected disease of the brain were examined with spin-echo sequences (TE = 20 and TE = 80), and results were compared with FLAIR sequences of several types with inversion times of 1800-3000 msec and echo times of 130-240 msec. Scans were assessed by two radiologists for lesion number, conspicuity, and extent. RESULTS: A total of 48 lesions or groups of lesions were recognized with both sequences. In 22 instances, more lesions were seen with FLAIR sequences, and, in the remaining 26, equal numbers were seen. In 42 lesions, conspicuity was better with FLAIR sequences, equal in five and worse in one cystic lesion. Lesion extent was better assessed in 28 of the 48 cases with FLAIR sequences and equally well seen in the remainder. CONCLUSION: By virtue of their long echo time and relative freedom from cerebrospinal fluid artifact FLAIR sequences provide high sensitivity to a wide range of disease. The basic sequence is easy to implement but is relatively time consuming.

Adult↗
PubMed1995

Magnetic resonance imaging in partial epilepsy: additional abnormalities shown with the fluid attenuated inversion recovery (FLAIR) pulse sequence.

Thirty six patients with a history of partial epilepsy had MRI of the brain performed with conventional T1 and T2 weighted pulse sequences as well as the fluid attenuated inversion recovery (FLAIR) sequence. Abnormalities were found in 20 cases (56%), in whom there were 25 lesions or groups of lesions. Twenty four of these lesions were more conspicuous with the FLAIR sequence than with any of the conventional sequences. In 11 of these 20 cases, lesions thought to be of aetiological importance were only seen with the FLAIR sequence. In eight this was a solitary lesion. In the other three, an additional and apparently significant lesion (or lesions) was only seen with the FLAIR sequence when another lesion had been identified with both conventional and FLAIR sequences. The 11 additional lesions or groups of lesions were seen in the hippocampus, amygdala, cortex, or subcortical and periventricular regions. No lesion was found with any pulse sequence in 16 (44%) of the original group of 36 patients. In the eight cases where a lesion was seen only with the FLAIR sequence, localisation was concordant with the electroclinical features. Two of the eight patients with solitary lesions seen only on the FLAIR sequence underwent surgery, after which there was pathological confirmation of the abnormality identified with imaging. In one patient with a congenital cavernoma, the primary lesion was best seen with a contrast enhanced T1 weighted spin echo sequence. In this selected series, the FLAIR sequence increased the yield of MRI examinations of the brain by 30%.

Adolescent↗
PubMed2005

Comparison of fat-suppressed T2-weighted fast spin-echo sequence and modified STIR sequence in the evaluation of the rotator cuff tendon.

OBJECTIVE: This study was performed to determine whether a modified version of the classic STIR sequence provides similar information about the integrity of the rotator cuff tendon as the commonly used fat-suppressed T2-weighted fast spin-echo sequence. SUBJECTS AND METHODS: Sixty-one consecutive MRI examinations of the shoulder in 57 patients were performed using a coronal oblique T1-weighted spin-echo sequence, a modified version of the STIR sequence, and a fat-suppressed T2-weighted fast spin-echo sequence. Three reviewers independently assessed the rotator cuff tendon using the coronal oblique modified inversion recovery sequence and T1-weighted spin-echo sequence. After a minimum of 4 weeks, reviewers assessed the rotator cuff tendon using the fat-suppressed T2-weighted fast spin-echo sequence and T1-weighted spin-echo sequence. The kappa statistic was used to measure the degree of concordance between interpretations when each sequence was used independently. The conditional probability that a full- and a partial-thickness tear would be diagnosed on both sequences was calculated. Image quality was assessed in a side-by-side comparison. RESULTS: The overall weighted kappa score was 0.82, which indicates excellent concordance between the two sequences. If a full-thickness tear of the rotator cuff tendon was found on the fat-suppressed T2-weighted fast spin-echo sequence, there was a 94.1% probability that the same conclusion would be reached using the modified inversion recovery sequence. If a partial-thickness tear was found on the fat-suppressed T2-weighted fast spin-echo sequence, there was an 80.3% probability that the same conclusion would be reached with the modified inversion recovery sequence. Fat suppression in the modified inversion recovery sequence was superior to that in the T2-weighted fast spin-echo sequence in 26-39% of the examinations. CONCLUSION: The modified inversion recovery sequence and fat-suppressed T2-weighted fast spin-echo sequence provide similar information about the integrity of the rotator cuff tendon.

Adult↗
PubMed1997

Prospective evaluation of bone marrow signal changes on magnetic resonance tomography during high-dose chemotherapy and peripheral blood stem cell transplantation in patients with breast cancer.

RATIONALE AND OBJECTIVES: The authors evaluate bone marrow signal changes on magnetic resonance (MR) imaging during high-dose chemotherapy and peripheral blood stem cell transplantation (PBSCT). METHODS: Fourteen patients with breast cancer without bone metastases underwent four sagittal MR imaging studies with T1-weighted, T2-weighted turbo spin-echo and inversion recovery sequences with short inversion time (STIR) of the lumbar spine: (1) during initial staging, (2) prior to high-dose chemotherapy after two cycles of induction chemotherapy, (3) early after PBSCT with a leukocyte exceeding 2000/microL, and (4) 6 to 8 weeks after PBSCT. Signal intensity ratios of averaged lumbar bone marrow to nucleus pulposus were measured and homogeneity was evaluated visually using a semiquantitative score. RESULTS: Compared with the initial finding (1): Signal intensity ratios were altered significantly at (2): T1-weighted: -22% +/- 14, P < 0.001; T2-weighted: -11% +/- 11, P < 0.01; STIR: +33% +/- 31, P < 0.01; Signal intensity ratios were altered significantly at (3): T2-weighted: -23% +/- 12, P < 0.001, STIR: -22% +/- 23, P < 0.01; and Signal intensity ratios were altered significantly at (4): only STIR: -16% +/- 19, P < 0.01. Homogeneity scores decreased at (3) for T1-weighted and STIR sequences (-1.6 +/- 0.5 to -2.0 +/- 0.7, P < 0.01 and -1.0 +/- 0.5 to -1.4 +/- 0.5, P < 0.01, respectively) and at (4) for the latter sequence (-1.0 +/- 0.5 versus -1.4 +/- 0.5, P < 0.01). At (4), T1-weighted images were less homogenous than initially in 3 of 14 (21%) patients. CONCLUSIONS: Magnetic resonance imaging demonstrates significant alterations of bone marrow composition during PBSCT but allows differentiation of benign therapy-related changes from those known in metastatic disease after completion of PBSCT.

Antineoplastic Agents↗
PubMedDate not supplied

Induced renal artery stenosis in rabbits: magnetic resonance imaging, angiography, and radionuclide determination of blood volume and blood flow.

To investigate the ability of MRI to detect alterations due to renal ischemia, a rabbit renal artery stenosis (RAS) model was developed. Seven rabbits had RAS induced by surgically encircling the artery with a polyethylene band which had a lumen of 1 mm, 1 to 2 weeks prior to imaging. The stenosis was confirmed by angiography, and the rabbits were then imaged in a 1.4 T research MRI unit. T1 was calculated using four inversion recovery sequences with different inversion times. Renal blood flow, using 113Sn-microspheres, and regional water content by drying were then measured. The average T1 of the inner medulla was shorter for the ischemia (1574 msec) than for the contralateral kidney (1849 msec), while no change ws noted in the cortex. Ischemic kidneys had less distinct outer medullary zones on IR images with TI = 600 msec than did contralateral or control kidneys. Blood flow to both the cortex and medulla were markedly reduced in ischemic kidneys compared with contralateral kidneys (119.5 vs. 391 ml/min/100 gm for cortex and 19.8 vs. 50.8 ml/min/100 gm for medulla). Renal water and blood content were less affected. Our rabbit model of renal artery stenosis with MRI, radionuclide, and angiographic correlation has the potential to increase our understanding of MR imaging of the rabbit kidney.

Angiography↗
PubMed1999

Towards a science of Alzheimer's disease management: a model based upon current knowledge of retrogenesis.

BACKGROUND: General relationships between dotage and infancy and childhood have been acknowledged for more than two millennia. Recent findings indicate precise relationships between functional, praxic, and feeding changes in the course of the degenerative dementia of Alzheimer's disease (AD) and inverse corresponding developmental sequences. Similar inverse relationships between AD and human development can be described for cognition and language skills; for physiologic measures of electroencephalographic activity, brain glucose metabolism, and developmental neurologic reflex changes; and for the neuropathologic and neuroanatomic progression of these processes. In AD, these processes may be termed "retrogenesis." The relevance of the retrogenesis model for AD management is explored. METHOD: The functional stages of AD can be translated into developmental age equivalents that can be utilized to explicate observed changes in the disease. RESULTS: The retrogenesis-based developmental age model can usefully inform an understanding of the general care needs, emotional and behavioral changes, and activity needs of the AD patient. This model must be amended by necessary caveats regarding physical differences, variations in age-associated pathology, differences in social and societal reactions, and differences in background between AD patients and their developmental age "peers." CONCLUSIONS: Knowledge of retrogenesis and the developmental age of the AD patient can form a nidus for the development of a nascent science of disease management. Such a science must ultimately incorporate not only appropriate caveats but also relevant universal human needs, such as those for dignity, love, and movement.

Adolescent↗
PubMed1997

Isolation and characterization of the dnaKJ operon from Actinobacillus actinomycetemcomitans.

The dnaKJ operon of Actinobacillus actinomycetemcomitans Y4 was cloned by the DNA-probing method using synthetic oligonucleotides designed on the basis of two conserved regions in DnaK/hsp70 proteins and sequenced by inverse PCR. The sequenced region was shown to contain two open reading frames coding for proteins analogous to DnaK and DnaJ.

Aggregatibacter actinomycetemcomitans↗
PubMed1999

[Usefulness of selective partial inversion recover (SPIR) sequences in optic nerve diseases].

PURPOSE: To evaluate the yield of SPIR sequences with fat suppression in the diagnosis of optic nerve lesions. MATERIAL AND METHODS: Ten patients with suspected optic nerve involvement on the basis of clinical data and abnormalities of visual evoked potentials were examined. MRI was performed with a 1.5 T unit (Philips NT 15) using T1 weighted conventional spin-echo and T1- and T2 weighted SPIR sequences with fat suppression. Axial images were obtained along the optic nerve course, while coronal images throughout the optic nerve axis; slices were 3 mm thick. Axial T2 weighted SPIR sequences were also performed with the volumetric technique (1.5 mm thickness); coronal and parasagittal reconstructions along the nerve axis were obtained too. After paramagnetic contrast medium injection, conventional T1 weighted and SPIR sequences were performed on axial and coronal planes. RESULTS: Optic nerve lesions consistent with the diagnosis of neuritis were demonstrated with T2 weighted images in 4 of 10 patients. No abnormalities and/or nerve enlargement were found on T1 weighted images. An enhancement area was seen after contrast medium injection in only one case. MRI showed a pilocytic astrocytoma in one patient and selective atrophy of the right optic nerve in another. MRI showed normal findings in 4 patients. CONCLUSIONS: T1 and T2 weighted fat-suppressed SPIR imaging of the optic nerve improves anatomical definition, lesion detection and characterization in optic nerve conditions.

Adult↗
PubMedDate not supplied

Usefulness of turbo-fluid-attenuated inversion-reovery (tFLAIR) sequence in diagnosing meningioma.

PURPOSE: We evaluated qualitatively and quantitatively the usefulness of turbo-FLAIR (tFLAIR) in diagnosing meningioma in comparison with the T2-weighted turbo spin echo (T2W-TSE) sequence. MATERIALS AND METHODS: Forty-eight patients diagnosed with meningioma were studied. In the qualitative study, we evaluated tumor delineation, contrast (Co) of tumor-to-CSF (cerebrospinal fluid), Co of tumor-to-brain parenchyma, Co of peripheral edema-to-brain parenchyma, and detectability of tumor margin. In quantitative study-1, using signal intensity (SI), we measured SI and calculated Co-SI of tumor-to-gray matter, Co-SI of tumor-to-white matter, Co-SI of peripheral edema-to-white matter, and Co-SI of tumor-to-CSF. In quantitative study-2, using film density, we measured density (De) on hard-copy film images and calculated Co-De for the same items as in quantitative study-1. RESULTS: In the qualitative study, tFLAIR was superior to T2W-TSE in tumor delineation, Co of tumor-to-CSF, Co of tumor-to-brain parenchyma, and Co of peripheral edema-to-brain parenchyma. In quantitative study-1, tFLAIR was superior to T2W-TSE in Co-SI of tumor-to-CSF, however, T2W-TSE was superior to tFLAIR in Co-SI of tumor-to-white matter. In quantitative study-2, tFLAIR was superior to T2W-TSE in all Co-De. CONCLUSION: tFLAIR was superior to T2W-TSE in the depiction of meningioma.

Adult↗
PubMed1999

Diffusion-weighted MR imaging of encephalitis.

OBJECTIVE: Our purpose was to evaluate how well diffusion-weighted MR imaging shows viral or bacterial encephalitis in comparison with conventional MR imaging that includes T1- and T2-weighted spin-echo and fluid-attenuated inversion-recovery sequences. CONCLUSION: In nine of the 13 patients examined, diffusion-weighted imaging was superior to other diagnostic imaging sequences (fluid-attenuated inversion-recovery sequences in eight patients and a T2-weighted spin-echo sequence in one patient). Diffusion-weighted imaging can serve as a method of detecting early encephalitic changes.

Bacterial Infections↗
PubMed2003

Efficacy of fibrin sealant in the management of complex anal fistula: a prospective trial.

PURPOSE: A prospective trial was conducted to establish long-term healing of complex idiopathic anorectal fistula, without extension, after fibrin glue treatment, with clinical assessment and magnetic resonance imaging to determine tract healing. METHODS: Twenty-two patients undergoing glue instillation after fistula curettage and irrigation were followed up for a median of 14 months. Clinical assessment, short tau inversion recovery sequence magnetic resonance imaging, and combined short tau inversion recovery and dynamic contrast-enhanced magnetic resonance imaging were performed at a median of three months postoperatively, and their ability to predict outcome in the presence of early skin healing was determined. RESULTS: Of 22 patients, 19 (86.5 percent) had transsphincteric fistulas, 1 (4.5 percent) had a suprasphincteric fistula, 1 (4.5 percent) had an extrasphincteric fistula, and 1 (4.5 percent) had a rectovaginal fistula. None had clinical or radiologic evidence of secondary extension. Despite skin healing in 17 (77 percent) of 22 patients at a median of 14 days after treatment, only 3 (14 percent) remained healed at 16 months. Magnetic resonance imaging with short tau inversion recovery sequences in combination with dynamic contrast-enhanced magnetic resonance imaging predicted outcome in all 10 assessments (100 percent), compared with short tau inversion recovery sequence alone in 16 (94 percent) of 17 assessments or clinical examination in 12 (71 percent) of 17 (P = 0.02). CONCLUSIONS: The success rate of fibrin glue application for complex anorectal fistulas without extension is 14 percent. Magnetic resonance imaging predicts outcome at an earlier stage than clinical examination.

Adult↗
PubMed2002

Detection and characterization of intracardiac thrombi on MR imaging.

OBJECTIVE: The aim of our study was to compare the diagnostic accuracy achieved using different MR techniques with the diagnostic accuracy achieved using transthoracic and transesophageal echocardiography to detect intracardiac thrombi. MATERIALS AND METHODS: Twenty-four patients with known or suspected intracardiac thrombi were examined using MR imaging and echocardiography. All MR examinations were performed on a 1.5-T MR scanner using dark-blood-prepared half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences, fast imaging steady-state free precession (trueFISP) cine sequences, and inversion recovery gradient-echo fast low-angle-shot (inversion recovery turbo FLASH) sequences after injection of 0.2 mmol/kg of gadolinium diethylene triamine pentaacetic acid. RESULTS: MR imaging and echocardiography revealed 12 thrombi-two in the right atrium, one in the right ventricle, three in the left atrium, and six in the left ventricle. Compared with echocardiography, MR imaging revealed three additional thrombi in the left ventricle; these thrombi were confirmed at surgery. All 15 thrombi appeared as filling defects on early contrast-enhanced inversion recovery turbo FLASH MR images. Only seven thrombi were detected on HASTE images, and 10 thrombi were seen on trueFISP images. Four thrombi showed enhancement 10-20 min after contrast material injection and were characterized as organized clots. CONCLUSION: Contrast-enhanced inversion recovery turbo FLASH sequences were superior to dark-blood-prepared HASTE and trueFISP cine MR images in revealing intracardiac thrombi. Compared with transthoracic echocardiography, MR imaging was more sensitive for the detection of left ventricular thrombi. The characterization of thrombi may be used to predict the risk of embolism, which is higher for subacute clots than for organized thrombi.

Adult↗