Recently, perfusion imaging has been of increasing interest in MRI. We applied this method for semiquantitative evaluation of hepatic parenchymal portal blood flow in patients with diffuse liver damage. Twenty patients with diffuse hepatic damage were divided according to the Child's Classification and studied. Gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) was administered into the superior mesenteric artery (SMA), and a dynamic series of T2*-weighted fast low angle shot (FLASH) images was obtained. We evaluated relative regional portal blood volume (rrPBV), mean transit time (MTT), and relative regional portal blood flow (rrPBF). The relationship between the rrPBV, rrPBF, and plasma indocyanine green retention rate test at 15 minutes (ICGR15 was also evaluated in 12 patients. Both rrPBF and rrPBV are significantly decreased in Child B & C patients compared with Child A patients. On the other hand, the MTT is significantly prolonged in Child B & C patients compared with Child A patients. Significant correlations were also noted between rrPBV and ICGR15 and between rrPBF and ICGR15. By means of selective catheterization into the SMA, we were able to estimate rrPBV, rrPBF, and MTT. This method may play a clinical role for assessment of regional portal perfusion in various diseases with diffuse liver damage.

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PubMedDate not supplied

Visualization of the cervical spinal cord with FDG and high-resolution PET.

PURPOSE: Our aim was to evaluate the visibility of the cervical spinal cord with [18F]2-fluoro-2-deoxyglucose (FDG) and a high-resolution PET scanner and to quantify the glucose utilization by the cervical cord. METHOD: Twenty-one normal subjects and three cervical myelopathy patients were studied. The visibility of the cervical spinal cord in sagittal and coronal sections was evaluated. The metabolic rate of glucose (MRGlu) and standardized uptake value (SUV) of FDG in the cord were calculated. RESULTS: The entire cervical spinal cord was clearly visualized in 57% of the subjects: the upper cord in 81%, the middle cord in 73%, and the lower cord in 57%. The MRGlu of the normal cord was 1.93 +/- 0.37 mg/100 g/min. SUV was constant across all the vertebral levels and negatively correlated with subject age. In the myelopathy patients, the SUV of the entire cervical cord was lower than in the age-matched normal subjects. CONCLUSION: These preliminary results indicate that the cervical spinal cord can be visualized as a normal structure in routine head and neck PET imaging and that FDG-PET may provide quantitative information about spinal cord disorders.

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PubMedDate not supplied

Blood volume of gliomas determined by double-echo dynamic perfusion-weighted MR imaging: a preliminary study.

BACKGROUND AND PURPOSE: After bolus injection, gadopentetate dimeglumine causes a T2* rate change in permeable tissue that is contaminated by the T1 shortening effect due to the leakage of contrast agent. Therefore, tumor vascularity as reported in previous single-echo perfusion-weighted MR imaging studies has been underestimated. Our aim was to quantitatively and qualitatively evaluate the degree of blood volume of glioblastoma multiformes (GBMs) underestimated by this T1 shortening effect. METHODS: We used double-echo dynamic MR imaging after a bolus injection of gadopentetate dimeglumine (double-echo perfusion-weighted MR imaging) to simultaneously determine tumor blood volume without (V(T1U)) and with (V(T1C)) T1 shortening correction. MR imaging was performed in five consecutive patients with GBMs. The ratios of V(T1U) and V(T1C) were calculated and compared by means of quantitative analysis. The degree of tumor blood volume as determined by V(T1U) and V(T1C) maps were qualitatively compared using a three-point scale. RESULTS: All GBMs showed contrast enhancement on postcontrast T1-weighted images. In all subjects, the values of V(T1U) were significantly lower than those of V(T1C) (mean +/- SD, 2.05 +/- 1.01 vs. 3.62 +/- 1.40, respectively [P <.05]), indicating that tumor blood volume obtained by double-echo perfusion-weighted MR imaging was significantly higher than that by single-echo imaging. In the qualitative analysis, tumor blood volume on the V(T1U) map was less conspicuous than that on the V(T1C) map. CONCLUSION: Careful attention should be paid to the underestimation of tumor blood volume resulting from T1 shortening effects when using single-echo perfusion-weighted MR imaging. Double-echo imaging may be more suitable for the analysis of blood volume in GBMs.

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PubMedDate not supplied

Midazolam and somatosensory evoked potentials.

The effect of midazolam, a water-soluble benzodiazepine, on the somatosensory evoked potentials (SEPs) following strong electrical stimulation of the upper lip, was investigated in Wistar albino rats. SEPs were recorded from the surface of the skull in the contralateral temporal area. A computer was used to obtain the averaged SEPs. The rats received intraperitoneal dosages of 1.25, 2.5, or 5.0 mg/kg of midazolam, or physiological saline. Relative amplitudes of the P(1)N(1) wave were reduced significantly after midazolam injection. Amplitude recovered to the control level about 120 min after the injection in the 1.25 mg/kg group. In 2.5 and 5.0 mg/kg groups, midazolam-induced suppression did not recover within 120 min. No significant differences were found in the latencies of P(1) and N(1) before and after midazolam injection. It is suggested that midazolam has a mild analgesic effect due to central suppression of the pain perception following noxious stimuli.

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PubMedDate not supplied

Midazolam does not affect the field potentials in the caudal part of the spinal trigeminal nucleus.

The effect of midazolam on the field potentials (FPs) in the caudal part of the spinal trigeminal nucleus following strong electrical stimulation of the upper lip was investigated in Wistar albino rats. The rats received i.p. dosages of 5, 10, or 20 mg/kg midazolam, or physiological saline. Relative amplitudes of the negative deflection were not suppressed after midazolam injection. No significant differences were found in the latencies of the potentials before and after midazolam injection. It is suggested that the main action site of midazolam may be located at a higher level than the spinal trigeminal nucleus.

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PubMedDate not supplied

Sedative effects and cardiorespiratory influences of intravenous flunitrazepam premedication.

Sedative effects and the influence on cardiorespiratory functions of flunitrazepam, 0.015 mg/kg intravenously, were studied in 13 healthy adult volunteers. Immediately after administration, 12 of the 13 subjects responded when their names were called, while one subject required gentle patting on the shoulder to evoke a response. The scores of EEG and electro-oculogram were decreased. Cardiorespiratory changes were mild and not significant clinically. Anterograde amnesia was remarkable. Equilibrium functions were normal at 180 min postdose. Only one subject complained of pain at injection. It was concluded that intravenous injection of 0.015 mg/kg flunitrazepam was an optimal dose for sedation in healthy adults.

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