Validation of a new noninvasive method (contrast-enhanced transthoracic second harmonic echo Doppler) for the evaluation of coronary flow reserve: comparison with intracoronary Doppler flow wire.
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OBJECTIVES: We tested the hypothesis that coronary flow reserve (CFR) in the left anterior descending coronary artery (LAD) as assessed by a new noninvasive method (contrast-enhanced transthoracic second harmonic echo Doppler) is in agreement with CFR measurements assessed by intracoronary Doppler flow wire. BACKGROUND: Contrast-enhanced transthoracic second harmonic echo Doppler is a novel noninvasive method to detect blood flow velocity and reserve in the LAD. However, it has not yet been validated versus a gold-standard method. METHODS: Twenty-five patients undergoing CFR assessment in the LAD by Doppler flow wire were also evaluated by contrast-enhanced transthoracic Doppler to record blood flow in the distal LAD at rest and during hyperemia obtained by adenosine i.v. infusion. In five patients CFR was evaluated twice (before and after angioplasty). RESULTS: As a result of the combined use of i.v. contrast and second harmonic Doppler technology, feasibility in assessing coronary flow reserve equaled 100%. The agreement between the two methods was high. In fact, in all but five patients the maximum difference between the two CFR measurements was 0.38. Overall, the prediction (95%) interval of individual differences was -0.69 to +0.72. Reproducibility of CFR measurements was also high. The limits of the agreement (95%) between the two measurements were -0.32 to +0.32. CONCLUSIONS: Coronary flow reserve in the LAD as assessed by contrast-enhanced transthoracic echo Doppler along with harmonic mode concurs very closely with Doppler flow wire CFR measurements. This new noninvasive method allows feasible, reliable and reproducible assessment of CFR in the LAD. (+info)
Evaluation of ectopic pregnancy by magnetic resonance imaging.
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Patients (n = 37) suspected of ectopic pregnancy were prospectively evaluated with magnetic resonance (MR) imaging to assess the capability of MR imaging in the diagnosis of ectopic pregnancy. Five levels of confidence were defined: diagnostic, suspicious, equivocal, questionable, and negative. Tubal wall enhancement and presence of tubal haematoma or gestational sac-like structure were considered diagnostic findings. There were 21 diagnostic, two suspicious, eight equivocal, and six negative findings. MR findings were compared with the surgical findings in 18 patients. Surgical confirmation was obtained in 12 diagnostic, two suspicious, and four equivocal studies. Using the MR diagnostic criteria for tubal pregnancy, MR had 12 true positive, three true negative, three false negative, and no false positive results for the diagnosis of tubal pregnancy. Retrospective analysis of the signal intensity of haematoma and ascites was performed for these 18 surgically confirmed cases. The predominant signal intensity of tubal haematoma was an intermediate signal on T1-weighted image (WI) and a low signal on T2WI. Ascites showed signal intensity higher than that of urine on T1WI in 100% of 13 cases. In conclusion, MR imaging with use of intravenous contrast material allows a specific diagnosis of tubal pregnancy, recognizing tubal wall enhancement and fresh tubal haematoma. (+info)
Renal zygomycosis: an under-diagnosed cause of acute renal failure.
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BACKGROUND: Invasive zygomycosis (mucormycosis) occurs predominantly in immunocompromised patients in whom it carries a grave prognosis. While renal involvement is not so uncommon in disseminated infection, isolated renal zygomycosis is rare. METHODS AND RESULTS: Forty-five patients with systemic zygomycosis were seen over a 12-year period from January 1986 to December 1997. Among these, 18 had renal involvement, nine with disseminated disease and nine with isolated renal zygomycosis. No underlying predisposing disease was identified in the majority of patients (72%). Renal involvement was confirmed at autopsy in 13 and by ante-mortem renal biopsy in five patients. The infection involved one kidney in five patients and was bilateral in the remaining. The manifestations included fever, flank pain, haematuria and pyuria with evidence of enlarged non-functioning kidneys on computerised tomography (CT). Of those with bilateral disease, 12 (92.3%) had anuric acute renal failure. Anti-fungal therapy was given to six patients (amphotericin B in mean total dose of 1.1 g) and of these only two with unilateral disease who also underwent nephrectomy survived while all the other 16 died. CONCLUSION: This study shows that renal zygomycosis has emerged as a cause of acute renal failure in the last decade since no patient with renal involvement was identified at our centre prior to 1986 even though autopsies have been done regularly in patients dying of unknown causes. Bilateral renal zygomycosis should be suspected in any patient who presents with haematuria, flank pain and otherwise unexplained anuric renal failure. Characteristic CT findings and an early renal biopsy can confirm the diagnosis and help in effective management of this serious disease. (+info)
Incidental detection of hippocampal sclerosis on MR images: is it significant?
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BACKGROUND AND PURPOSE: The prevalence of hippocampal sclerosis in the general nonepileptic patient population is not well described. While reports of its association with partial complex seizures are abundant, its absence in nonafflicted patients is generally presumed but not well documented. To test the hypothesis that hippocampal sclerosis is specific for epilepsy, we reviewed the MR imaging studies of 207 patients referred for hearing loss to determine whether high-resolution MR imaging could detect unsuspected hippocampal sclerosis in nonepileptic patients. METHODS: Our institution screens patients with hearing loss by using high-resolution coronal and axial temporal bone MR imaging that includes the hippocampus within the imaging volume. We retrospectively reviewed 207 studies randomly selected from this database. RESULTS: The hippocampus was normal in 205 patients; in the remaining two patients we identified one or more primary determinants for hippocampal sclerosis. Subsequent retrospective chart review revealed that both patients had had previously diagnosed seizure disorders. CONCLUSION: The imaging determinants of hippocampal sclerosis are not prevalent in nonepileptic patients. Incidental identification of hippocampal sclerosis on MR images is uncommon and significant, and should prompt further clinical investigation to exclude a seizure disorder. (+info)
BACKGROUND AND PURPOSE: Diffuse axonal injury (DAI) accounts for a significant portion of primary intra-axial lesions in cases of traumatic brain injury. The goal of this study was to use diffusion-weighted MR imaging to characterize DAI in the setting of acute and subacute traumatic brain injury. METHODS: Nine patients ranging in age from 26 to 78 years were examined with conventional MR imaging (including fast spin-echo T2-weighted, fluid-attenuated inversion-recovery, and gradient-echo sequences) as well as echo-planar diffusion-weighted MR imaging 1 to 18 days after traumatic injury. Lesions were characterized as DAI on the basis of their location and their appearance on conventional MR images. Trace apparent diffusion coefficient (ADC) maps were computed off-line with the diffusion-weighted and base-line images. Areas of increased signal were identified on the diffusion-weighted images, and regions of interests were used to obtain trace ADC values. RESULTS: In the nine patients studied, isotropic diffusion-weighted images showed areas of increased signal with correspondingly decreased ADC. In one case, decreased ADC was seen 18 days after the initial event. CONCLUSION: Decreased ADC can be demonstrated in patients with DAI in the acute setting and may persist into the subacute period, beyond that described for cytotoxic edema in ischemia. (+info)
Optimization of gray/white matter contrast with fast inversion recovery for myelin suppression: a comparison of fast spin-echo and echo-planar MR imaging sequences.
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We compared two MR imaging sequences, fast inversion recovery for myelin suppression (FIRMS) and echo-planar FIRMS (EP-FIRMS), for depicting gray/white matter contrast. In 18 patients, the frequency bandwidth (BW) was optimized for each sequence; in nine patients, the BW was held constant. In the BW-optimized group, the mean contrast-to-noise ratio (C/N) was three times higher with the FIRMS sequence. In the BW-constant group, the mean C/N was 27% higher with the EP-FIRMS sequence; however, geometric distortion degraded the EP-FIRMS images excessively. For optimal gray/white contrast, FIRMS appears to be the superior pulse sequence. (+info)
MR line-scan diffusion-weighted imaging of term neonates with perinatal brain ischemia.
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BACKGROUND AND PURPOSE: MR diffusion-weighted imaging provides early demonstration of neonatal brain infarction. The evolution and limitations of diffusion-weighted imaging findings in newborns, however, have not been evaluated. Using line-scan diffusion imaging (LSDI), we investigated perinatal ischemic brain injury. METHODS: Nineteen term newborns (age, 9 hours to 8 days; mean age, 2.6 days) with perinatal brain ischemia were evaluated using LSDI (1520/62.5/1 [TR/TE/excitations]) (b maximum = 750 s/mm2) and T1- and T2-weighted spin-echo (conventional) MR imaging. Follow-up examinations were performed in seven patients and autopsy in one. Apparent diffusion coefficients (ADCs) were measured in deep gray matter, white matter, the cortex, and focal lesions. RESULTS: Based on conventional MR imaging or pathologic findings, patients were divided into two groups. Group 1 (n = 12) had symmetric/diffuse injury consistent with global hypoperfusion. Group 2 (n = 7) had focal/multifocal injury suggesting cerebrovascular occlusion. ADCs were abnormal at initial examination in 10 newborns in group 1 and in all newborns in group 2. The results of LSDI were abnormal before conventional MR imaging was performed in three newborns in group 1. ADCs were maximally decreased between days 1 and 3 in deep gray matter, perirolandic white matter, and focal lesions. Delayed decreases in ADCs were observed in subcortical white matter from days 4 through 10 in three patients in group 1. CONCLUSION: After global hypoperfusion, LSDI showed deep gray matter and perirolandic white matter lesions before conventional MR imaging. LSDI may underestimate the extent of injury, however, possibly because of variations in the compartmentalization of edema, selective vulnerability, and delayed cell death. Differences in LSDI of symmetric/diffuse and focal/multifocal lesions may reflect differences in pathophysiology or timing of the injury. These findings may have implications for acute interventions. (+info)
Comparison of three MR sequences for the detection of cervical cord lesions in patients with multiple sclerosis.
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BACKGROUND AND PURPOSE: Improving the sensitivity of MR imaging for the detection of multiple sclerosis (MS) lesions in the cord might be useful in the diagnostic workup and could lead to a better understanding of the evolution of the disease. The purpose of this study was to compare fast spin-echo (FSE) with magnetization transfer-prepared gradient-echo (MT-GE) and fast short-inversion-time inversion recovery (fast-STIR) MR sequences to determine which is best for imaging cervical cord lesions in MS patients. METHODS: FSE, MT-GE, and fast-STIR MR images were obtained in 56 MS patients and 10 healthy control subjects with a 1.5-T MR system and a phased-array coil. Cord lesions seen on images obtained with each sequence were counted by two observers in two stages (stage 1: random review of the complete sets of images from each technique; stage 2: side-by-side review with a retrospective count of lesions). RESULTS: At the end of stage 1, a mean of 1.16 cord lesions per patient were seen on FSE images, 1.57 on MT-GE images (35% more than on FSE), and 1.92 on fast-STIR images (66% more than on FSE). Two or more cervical cord lesions were found on 16 FSE images (29%), 23 on MT-GE images (46%), and 30 on fast-STIR images (54%). Differences were reduced after stage 2: MT-GE detected 22% more lesions and fast-STIR 36% more lesions than FSE. Considering the three sequences together, 113 cervical cord lesions were seen in 50 patients (89%). CONCLUSION: Both MT-GE and fast-STIR sequences depict more cervical cord MS lesions than the FSE sequence, with fast-STIR having the best sensitivity. Fast-STIR MR images may be useful for the diagnostic workup of patients with suspected MS and for improving our understanding of the evolution of MS. (+info)