Lactate quantification by proton magnetic resonance spectroscopy using a clinical MRI machine: a basic study.

The purpose of this study was to establish quantification method of lactate concentration by proton magnetic resonance spectroscopy (MRS) carried out using a conventional 1.5-T MRI machine. We used a lactate phantom with known concentrations (1, 1.5, 3, 6, 12 and 14 mmol/L). As a clinical example, a patient with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) was evaluated. Proton MRS was carried out using a clinical 1.5-T super-conducting magnetic resonance whole-body system. Data were acquired by point resolved spectroscopy. A coupling constant of J = 7.35 Hz (2/J = 272 ms) and two long in-phase echo time of 272 ms and 544 ms were used to calculate the T2 relaxation time. The tissue water signal was used as an internal standard to quantify lactate. The correlation coefficient R between the calculated lactate concentrations and the known concentration of lactate was 0.99 with a constant factor of 0.32 (1/3.14). In patients with MELAS, the lactate concentration measured by MRS was 6.2 mmol/kg wet weight, which is similar to the value obtained in previous studies. In the present study, we have established a reliable method for lactate quantification in a phantom study and have shown a sample of clinical case of MELAS.

Perfusion-weighted MRI of spinal dural arteriovenous fistula.

A 72-year-old woman was admitted with rapidly progressive paraplegia and sphincter disturbance. T2-weighted images of the thoracic spine showed intramedullary high signal with flow voids suggesting dilated medullary veins. Conventional spinal angiography demonstrated a dural arteriovenous fistula draining into perimedullary veins. Perfusion-weighted MRI demonstrated a prolonged mean transit time and increased blood volume in the high-signal area. The loss of normal perfusion gradient and venous hypertension and were thought to produce these differences. The time-to-peak was almost identical in the high-signal and isointense areas, although the bolus of contrast medium arrived earlier in the former. Arteriovenous shunting was thought to cause faster inflow. These changes may have resulted in increased blood volume in the spinal cord. The high signal has been attributed to oedema due to venous congestion, but there has been no histological confirmation. Perfusion MRI in this case supports this hypothesis.

Intraoperative angiography in the surgical treatment of cerebral arteriovenous malformations and fistulas.

BACKGROUND: The role of intraoperative angiography in the surgical treatment of cerebrovascular malformations remains controversial. The authors report on their experiences with intraoperative angiography in a series of 20 cases with cerebrovascular malformation to determine whether the use of intraoperative angiography has a favorable impact on the surgical treatment of cerebrovascular malformations. METHODS: Intraoperative angiography was performed in the surgical resection of arteriovenous malformation in 18 patients and in the surgical obliteration of arteriovenous fistula in 2 patients. The incidence of unexpected findings, such as residual nidus, demonstrated by intraoperative angiography was determined. FINDINGS: High-quality subtraction images were obtained by intraoperative angiography in every case and the findings prompted an additional procedure in 1 case that displayed an unexpected residual nidus (5.6%). There were no complications from the intraoperative angiography procedure. INTERPRETATION: Intraoperative assessment of technical results prior to wound closure offers the neurosurgeon the opportunity to resect or obliterate a vascular malformation completely, obviating a second operation.

Chronological change of brain abscess in (1)H magnetic resonance spectroscopy.

We studied chronological magnetic resonance spectral changes in brain abscesses before and after medical and/or surgical treatment. We examined five patients with MRI imaging and (1)H magnetic resonance spectroscopy (MRS) on two or more occasions, using two volume-of-interest patterns, and saw chronological changes related to the evolution of the abscess. A spectrum specific for brain abscess was found in three of the five cases, while two showed a single lactate peak in the first study. In two cases, phenylalanine or alanine appeared in the second study. We observed the disappearance of the specific spectra and a single lactate peak following surgery. Only one patient showed different spectra in different volume of interest.

Intracranial hypotension.

The authors present the case of a 55-year-old man suffering from intractable spontaneous intracranial hypotension, in whom conservative treatment with 19 weeks of bed rest was not effective. In this period the patient twice underwent surgery for bilateral chronic subdural hematoma, a complication of spontaneous intracranial hypotension. Conventional radionuclide cisternography, magnetic resonance imaging, and computerized tomography myelography did not demonstrate cerebrospinal fluid (CSF) leakage. Repeated radionuclide cisternography with the patient in an upright position revealed leakage of the tracer at upper cervical levels. Computerized tomography myelography with breath holding also showed CSF leakage of the contrast medium bilaterally at upper cervical levels. The patient underwent surgery, and bilateral C-2 and C-3 spinal nerve root pouches were sealed off from the subarachnoid space with oxidized cellulose cotton and fibrin glue. Epiarachnoid spaces around the root sleeves were also sealed to ensure complete resolution of the CSF leakage. After the surgery, the patient was completely free of the disease. In the case of intractable persistent spontaneous intracranial hypotension, surgical treatment is preferable to long-term conservative management. To identify CSF leakage, radionuclide cisternography with the patient in the upright position is useful. When obvious leakage is encountered, surgical sealing of the lesion should be performed via a subarachnoid approach.

Transcatheter embolization of mycotic aneurysm of the subclavian artery with metallic coils.

Mycotic aneurysms of the subclavian artery are rare. This report describes an experience of 2 rare cases in which transcatheter embolization with metallic coils was performed for the management of these lesions alternative to surgery. Two patients who had been treated with chemotherapy for malignant neoplasms were diagnosed as having mycotic aneurysms of the left subclavian artery. The causes of these lesions were presumed to be the invasion of the arterial wall by the pulmonary abscess in case 1, and wound infection after placement of the reservoir for intraarterial chemotherapy in case 2. In both cases, proximal and distal sites of the aneurysm were embolized with metallic coils. In case 1, the vertebral artery was also embolized with Guglielmi detachable coils to avoid retrograde blood flow. Both aneurysms were completely occluded by a single embolization. In case 1, although weakness and paresthesia of the left hand remained, lethal hemoptysis due to aneurysmal fistulization to the lung parenchyma ceased. In case 2, no neurological deficit except for mild paresthesia in the left thumb had been observed. Both patients died of primary disease 10 and 5 months after the procedure. Transcatheter embolization is technically feasible and effective enough to treat the mycotic aneurysm of the subclavian artery even in the situation in which the surgical option seems to be difficult or risky.

Distal anterior choroidal artery aneurysm associated with an arteriovenous malformation. Intraoperative localization and treatment.

BACKGROUND: Distal anterior choroidal artery aneurysms are rare. The outcome of patients with distal anterior choroidal artery aneurysms has been poor, and the treatment of such aneurysms is surgically challenging. CASE DESCRIPTION: The authors describe the case of an 8-year-old girl with a ruptured distal anterior choroidal artery aneurysm associated with an arteriovenous malformation (AVM). The patient experienced sudden onset of headache and vomiting. Computed tomography revealed an intraventricular haemorrhage, and cerebral angiography demonstrated an aneurysm arising from the distal portion of the right anterior choroidal artery. The patient also had an AVM in the ipsilateral temporal lobe fed by the branches of the middle cerebral artery. A right frontotemporal craniotomy was performed with the aid of intraoperative angiography to eliminate both the AVM and the aneurysm. Intraoperative angiography was helpful in confirming the complete removal of the AVM and in accurate localization of the small and deeply placed distal anterior choroidal artery aneurysm. Both the AVM and the aneurysm were successfully treated and the patient was discharged without any neurological deficits. CONCLUSION: This case is the youngest reported patient with a distal anterior choroidal artery aneurysm. This report is also the first to describe an association of such an aneurysm with an AVM. The etiology of the aneurysm formation in this case and surgical strategy for deeply placed vascular lesions are discussed.

Diagnosis of spontaneous intracranial hypotension by using magnetic resonance myelography. Case report.

The authors describe a case of spontaneous intracranial hypotension in which the leakage site was determined by using magnetic resonance (MR) myelography. This technique demonstrated the route of cerebrospinal fluid (CSF) leakage, whereas other methods failed to show direct evidence of leakage. Magnetic resonance myelography is a noninvasive method that is highly sensitive in detecting CSF leakage. This is the first report in which a site of CSF leakage was detected using MR myelography.

Standardization of broth microdilution method for Mycobacterium tuberculosis.

Indirect drug susceptibility tests of Mycobacterium tuberculosis was done to investigate the accuracy and feasibility of a broth microdilution method (BMM) for determining minimal inhibitory concentrations of conventional drugs against M. tuberculosis. Test drugs included isoniazid (H), rifampicin (R), ethambutol (E), streptomycin (S) and pyrazinamide (Z). Fifty isolates of M. tuberculosis from patients who had never received drug therapy, and H37Rv strain for control, were evaluated in the system. When comparing this method with the gold standard proportional method in Lowenstein-Jensen medium, sensitivity of 100% for all drugs and specifities of 91, 100, 96, 98 and 85% were observed respectively for H, R, E, S and Z. The BMM was read faster (14-20 days) than the proportional method (20-28 days). The microdilution method evaluated allows the testing of multiple drugs in multiple concentrations. It is easy to perform and does not require special equipment or expensive supplies. In contrast to radiometric method it does not use radioactive material.

[Application of a new MR microscope using an independent console system (MRMICS) for biological tissues in vitro].

We studied microscopic MR images of the normal appendix in vitro using a new MR microscope system: MR Microscope using an Independent Console System (MRMICS). The MRMICS was placed in the clinical MR room, and the probe box was fixed on the bed of the 1.5 T clinical MR machine. T1-, T2-, and proton density-weighted images were obtained using spin echo sequences with an in-plane pixel size of 100 x 100 microns. Zonal structures of the appendix were clearly demonstrated with different contrast by different sequences. Therefore, the MRMICS is a useful add-on system for investigating microscopic MR images of biological tissues in vitro.

Early phase adaptations of muscle use and strength to isokinetic training.

The purpose of this study was to investigate the effect of short periods of isokinetic resistance training on muscle use and strength. Seven men trained the right quadriceps femoris muscles (QF) 9 d for 2 wk using 10 sets of 5 knee extensions each day. Isometric and isokinetic torques of QF were measured at six angular velocities. Cross-sectional areas (CSA) of QF were determined from axial images using magnetic resonance imaging (MRI). Transverse relaxation time (T2) and activated area of QF, which represented the area greater than the mean resting T2 + ISD in MR[pixels, were calculated at rest and immediately after repetitive isokinetic knee extensions based on T2-weighted MR images. Muscle fiber types, fiber area, and phosphofructokinase (PFK) activities were determined from biopsies of the vastus lateralis muscle. No changes were found in CSA of QF, muscle fiber types, fiber area, and PFK activities after the training. Isometric and isokinetic peak torques at 60-240 degrees x s(-1) and relative area of QF activated by knee extensions increased significantly after the training. These results suggest that muscle strength increases after short periods of isokinetic resistance training without muscle hypertrophy would be due to increased muscle contractile activity.

Percutaneous transluminal angioplasty for atherosclerotic stenosis of the intracranial cerebral arteries. initial results and long-term follow-up.

Percutaneous transluminal angioplasty (PTA) was carried out 52 times for 49 lesions in 47 cases of atheroscrelotic stenosis of the intracranial or skull base cerebral arteries. The stenotic lesions involved the middle cerebral artery in 21 cases, the basilar artery in eight cases, the internal carotid artery (petrous-supraclinoid portion) in 15 cases, and the intracranial vertebral artery in five cases. Nearly all cases were symptomatic, such as TIA or stroke, and the degree of stenosis ranged from 70 to 99 percent, with a mean of 80 percent. PTA was performed using a STEALTH balloon angioplasty catheter. In these trials, PTA was successfully performed (as indicated by a residual stenosis under 50%) 41 times. The initial success rate was 79% and stenosis was reduced from 80% to 25%. Clinical follow-up was performed from 7 to 84 months with a mean of 44 months. During this period, death due to myocardial infarction or pneumonia occurred in five cases, stroke related to previous PTA occurred ih one case (due to re-stenosis) and stroke unrelated tl? previous PTA occurred in two cases. Angiographic follow-up was performed in 31 cases after 41 successful PTA procedures. Re-stenosis was seen in 20% of the cases, symptomrltic complications occurred in 6%, and asymptomatic complications occurred in 6% of the cases. One case suffered severe subarachnoid hemorrhage just after the PTA due to preexisting aneurysm rupture and he died a week after the PTA. So mortality in this series was 2%. From the results described here, we may conclude that PTA of the intracranial or skull base cerebral artery is technically feasible, and it can be performed with relatively low risk. From our results, it may be a useful method and effective for long-term survival of patients. But results from a larger number of patients and more long-term follow-up data are still necessary in order to evaluate the safety and usefulness of this method.

Leptomeningeal angiomatosis accompanied by hair follicle nevus.

A 5-day-old male infant with leptomeningeal angiomatosis accompanied by hair follicle nevus and congenital alopecia is reported. Admitted for frequent left hemiconvulsions, he had three small papular lesions around his right eye and ipsilateral alopecia from the frontal to parietal areas. Histopathological examination of the papular lesions revealed crowding of hair follicles. There were no other skin lesions and no ophthalmic abnormalities. Ictal EEG showed a theta burst in the right parietal area. Computed tomography of the brain revealed cerebral atrophy and a slightly high intensity lesion in the right parietal and occipital lobes with calcification. Gyriform enhancement was demonstrated by contrast MRI in these areas. The pathogenesis is discussed. This case may represent a previously unknown neurocutaneous syndrome.

Percutaneous Transluminal Angioplasty for Atherosclerotic Stenosis of the Intracranial Cerebral Arteries. Special reference to the device for reducing the complications drawn from the analysis of our complicated cases.

SUMMARY: Percutaneous transluminal angioplasty (PTA) was carried out 43 times for 40 lesions in 38 cases of atheroscrelotic stenosis of the intracranial or skull base cerebral arteries. The stenotic lesions involved the middle cerebral artery in 15 cases, the basilar artery in seven cases, the internal carotid artery (petrous-supraclinoid portion) in 14 cases, and the intracranial vertebral artery in four cases. Nearly all cases were symptomatic, such as TIA or stroke, and the degree of stenosis ranged from 70 to 99 percent, with a mean of 80 percent. PTA was performed using a STEALTH balloon angioplasty catheter. In these trials, PTA was successfully performed (as indicated by a residual stenosis under 50%) 36 times. The initial success rate was 84% and stenosis was reduced from 80% to 25%. Clinical follow-up was performed from 3 to 62 months with a mean of 40 months. During this period, death due to myocardial infarction or pneumonia occurred in four cases, stroke related to previous PTA occurred in one case (due to re-stenosis) and stroke unrelated to previous PTA occurred in two cases. Angiographic follow-up was performed in 30 cases after 36 successful PTA procedures. Re-stenosis was seen in 20% of the cases, symptomatic complication occurred in 7%, and asymptomatic complications occurred in 7% of the cases. There was no mortality in this series. From analysis of complicated cases, there are several characteristic findings on the stenotic lesion. These are the stenotic lesions that located near the bifurcation, involving long segment, or showing irregular shape which is including ulcer or dissection. It is important to keep a fundamental and safe technique to reduce the complication. And besides, it is very important to keep the strict indication and to avoid the high-risk patient from a morphological point of view.

Intra-aneurysmal Embolization for the Treatment of Cerebral Aneurysms Using Detachable Coils.

SUMMARY: From October 1993 to February 1998, intraaneurysmal embolization by endovascular treatment with detachable coils was performed for 41 cases of cerebral aneurysm. As a detachable coil, interlocking detachable coils (IDC) were used in the initial 15 cases and Guglielmi detachable coils (GDC) were used in the subsequent 26 cases. As for 15 cases treated with IDC, complete occlusion was performed in 9 cases, subtotal occlusion in 4 cases and partial occlusion in 2 cases. In one of the partial occluded cases, a coil compaction occurred 6 months after embolization. Distal emboli were recognized on CT after embolization in 3 cases, however, only one case was symptomatic. Intra-operative bleeding occurred in one case, but no obvious hemorrhage after coil embolization in any case. As for 26 cases treated with GDC, complete occlusion was performed in 18 cases, subtotal occlusion in 8 cases. In one case of basilar-tip aneurysm, a mild coil compaction occurred 6 months after embolization. Distal emboli were recognized on CT after embolization in 3 cases, however, only one case was symptomatic (minor stroke). No intra-operative bleeding and no obvious hemorrhage after coil embolization occurred in any case. From our experiences, treatment for poor-grade ruptured aneurysm is still difficult, but intraaneurysmal embolization for cerebral aneurysms using detachable coils is possible and a useful alternative, especially for surgically difficult aneurysms. The results of treatment of aneurysm with GDC are much better than those with IDC, so the indications for intra-aneurysmal embolization with GDC might increase in the future.

[Functional MRI employing diazepam; a proposal of neuropharmacological fMRI].

Employing the active benzodiazepine receptor (BZR) ligands, we have used BOLD fMRI to elucidate the effects of these drugs on brain function. The sequential MRI was performed with a 1.5T clinical scanner (Philips GYROSCAN) using a FLASH sequence with the following parameters: TR/TE, 100/45 msec; flip angle, 25 degrees; matrix size, 128*128; 2 averages; for 64 image acquisitions in 32 min. First, 2 mg of diazepam was administrated intravenously at the beginning of the 5th, 15th, 25th, and 35th acquisitions. Then, flumazenil was administrated at the beginning of the 45th (0.2 mg) and 55th (0.3 mg) acquisitions in order to reverse the effect of diazepam. Data processing was made employing Akaike Information Criterion to detect if there were intensity changes after the medication among the trends of intensity changes. Diazepam administration decreased the intensity for a while and flumazenil increased one. In the case of the left frontal glioma with focal epileptogenicity, intensity changes were detected around the tumor. Since the neuronal function consists of the trans-neuronal communications employing neurotransmitters, the result on the modulation of this passage depends on the neuronal function related to the transmitter: gamma-amino butyric acid (GABA) in this instance for the effects of these medications to epilepsy. The change in the local blood flow is the result of the local neuronal activity. Therefore, we speculate that this neuropharmacological functional MR image may reflect the neuronal function related to the GABAegic neurotransmitter system. In addition to elucidating basic neurotransmitter function mechanisms, we believe this technique may have clinical utility in the pre-surgical evaluation of patients with intractable seizure disorders. In this respect, this paper presents a new spectrum of fMRI that is capable to study a part of neurotransmitter function employing the BZR ligands, reversing the effect of the agonist with the competitive antagonist, for the first experience, to propose the neuropharmacological functional MR images to have clinical utility in patients with intractable epilepsy in the interictal state.

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.

The evaluation of preoperative embolization of meningioma.

SUMMARY: To evaluate the efficacy of preoperative embolization of meningioma, we examined the correlation between the angiographic disappearance of the tumor blush after the embolization and the volume of blood loss and transfusion intraoperatively. Preoperative embolization of meningioma with intravascular neurosurgery was attempted for 42 trials, 41 cases from July 1989 to December 1995. There were no major complications attributed to the embolization procedure. As a subjective assessment in 23 cases the information from the surgeon following the operation was obtained. The angiographic disappearance of the tumor blush and reducing of the bleeding from tumor could be considered to be statiscally significant (p < 0.05). As an objective assessment in 37 cases following operation, the volume of both intraoperative blood loss and blood transfusion was examined. The angiographic disappearance of the tumor blush and reduced intraoperative blood transfusion could be also considered to be statiscally significant (p < 0.05), otherwise reduced intraoperative blood loss failed to reach the significance level. 1n this study the efficacy of preoperative embolization of meningioma has been especially shown to reduce intraoperative blood transfusion significantly, therefore it is very useful to increase the chance of complete tumor removal with more safely and less invasively.