Neuronal dysfunction and hemodynamic disturbance due to venous congestion in dural arteriovenous fistula revealed by 123I-iomazenil SPECT.

OBJECTIVE: Retrograde leptomeningeal venous drainage (RLVD) of a dural arteriovenous fistula (dAVF) is associated with neurological morbidity and unfavorable outcomes. However, the direct damage to cortical neurons by dAVF with RLVD has not been elucidated. 123I-iomazenil (123I-IMZ) SPECT can reveal cerebral blood flow and cortical neuronal damage in early and late images, respectively. This study aimed to assess the cerebral venous congestive encephalopathy caused by dAVF using 123I-IMZ SPECT. METHODS: Based on the pre- and posttreatment MRI findings, patients were divided into three groups: a normal group, an edema group, and an infarction group. Radioactive counts in the early and late images of 123I-IMZ SPECT were investigated using the affected-to-contralateral side asymmetry ratio (ACR). RESULTS: None of the patients in the normal group showed any symptoms related to venous congestion. In contrast, all the patients in the edema and infarction groups developed neurological symptoms. The ACR in early images in the edema group was significantly lower than that in the normal group and significantly higher than that in the infarction group. The ACR in the late images of the infarction group was significantly lower than those of the normal and edema groups. After treatment, the neurological signs disappeared in the edema group, but only partial improvement was observed in the infarction group. The ACR in early images significantly improved after treatment in the edema group, but the ACR in late images did not change in any groups. CONCLUSIONS: 123I-IMZ SPECT is useful for evaluating hemodynamic disturbances and neuronal damage in dAVFs. The reduction in early images was correlated with the severity of venous congestive encephalopathy, and the significant reduction in late images is a reliable indicator of irreversible venous infarction caused by RLVD.

Neuroimaging, genetic, and enzymatic study in a Japanese family with a GBA gross deletion.

INTRODUCTION: Glucocerebrosidase gene (GBA) variants are associated with Parkinson's disease (PD) and dementia with Lewy bodies (DLB). The molecular mechanisms underlying these diseases with GBA variants, however, are not well understood. In order to determine the effect of a deletion mutation in GBA, we performed a neuroimaging, genetic, and enzymatic study in a Japanese family with a gross deletion of exons 3 to 11 in GBA. METHODS: We performed [123I] FP-CIT SPECT and [123I] N-isopropyl-p-iodoamphetamine SPECT (IMP-SPECT), and determined GBA expression and glucocerebrosidase (GCase) activity in leukocytes in two GBA-associated PD patients and nine unaffected individuals (including four mutation carriers) in a Japanese family with a heterozygous gross deletion mutation in the GBA gene. RESULTS: The two PD patients and two of the four clinically unaffected carriers showed decreased [123I] FP-CIT uptake. IMP-SPECT showed a pattern like that in DLB in one patient. When we compared PD patients with GBA mutations with clinically unaffected carriers, there was a poor correlation between the development of PD and the expression level of GBA or GCase activity. CONCLUSION: We confirmed the gross deletion mutation in the GBA gene, which appeared to be associated with the PD or reduced [123I] FP-CIT in this family. However, since we cannot conclude whether a reduction of GCase activity is directly correlated with the pathogenesis of PD or not, longitudinal follow-up of this family is needed.

Cerebral hemodynamic disturbance in dural arteriovenous fistula with retrograde leptomeningeal venous drainage: a prospective study using (123)I-iodoamphetamine single photon emission computed tomography.

OBJECT: The severity of cerebral hemodynamic disturbance caused by retrograde leptomeningeal venous drainage (RLVD) of a dural arteriovenous fistula (dAVF) is related to neurological morbidity and unfavorable outcome. However, the cerebral hemodynamics of this disorder have not been elucidated well. The aim of this study was to assess the relationship between the cerebral venous congestive encephalopathy represented as a high-intensity area (HIA) on T2-weighted MR images and the cerebral hemodynamics examined by (123)I-iodoamphetamine (IMP) single photon emission computed tomography (SPECT), as well as the predictive value of (123)I-IMP SPECT for the development and reversibility of venous congestion encephalopathy. METHODS: Based on the pre- and posttreatment T2 HIAs associated with venous congestion encephalopathy, patients were divided into 3 groups: a normal group, an edema group, and an infarction group. The regional cerebral blood flow (rCBF) at the region with RLVD was analyzed by (123)I-IMP SPECT, and the results were compared among the groups. RESULTS: There were 11, 6, and 3 patients in the normal, edema, and infarction groups, respectively. No patients in the normal group showed any symptoms related to venous congestion. In contrast, all patients in the edema and infarction groups developed neurological symptoms. The rCBF in the edema group was significantly lower than that in the normal group, and significantly higher than that in the infarction group. The cerebral vascular reactivity (CVR) of the infarction group was significantly lower than that of the normal and edema groups. After treatment, the neurological signs disappeared in the edema group, but only partial improvement was seen in the infarction group. The rCBF also significantly increased in the normal and edema groups, but not in the infarction group. CONCLUSIONS: Quantitative rCBF measurement is useful for evaluating hemodynamic disturbance in dAVF with RLVD. The reduction of rCBF was strongly correlated with the severity of venous congestive encephalopathy, and loss of CVR is a reliable indicator of irreversible venous infarction caused by RLVD.

[The association of age and tracer clearance determined radionuclide cisternography].

We aimed to study tracer kinetics in radioisotope (RI) cisternography. For this purpose, we analyzed the RI images of 36 individuals in whom absence of cerebrospinal fluid (CSF) leakage was confirmed. For the semiquantitative assessment of tracer clearance, the geometric mean of the RI count in the anterior and posterior images was obtained for the entire head as well as for the whole spinal axis. After correcting for the radioactive decay of the tracer, tracer clearance was expressed as a ratio of the count in the range of the whole CSF space at different time points to that at the time of tracer delivery. Tracer clearance from the CSF space was not related to the degree of cranial transport of the tracer in 1 hour, but was significantly related with the age of the patients. At 24 hours after the injection, tracer clearance was significantly faster in the younger patients (Group I: age < 40 years) than in the older patients (Group II: age > or = 40 years). The cranial transport of the tracer appeared to be rapid in group I; however, the difference between these 2 groups was not significant. These results indicate that age should be taken in account while establishing the reference values for tracer kinetics in normal individuals.

Patulous Eustachian tube in spontaneous intracranial hypotension syndrome.

A 48-year-old slender woman presented with a rare case of spontaneous intracranial hypotension syndrome manifesting as patulous Eustachian tube. The patient complained of sudden onset of ear fullness and nasal voice as well as typical orthostatic headache. Patulous Eustachian tube was identified by observation of synchronous movement of the tympanic membrane with respiration and swallowing. The diagnosis of spontaneous intracranial hypotension was confirmed by negative cerebrospinal fluid pressure, and typical magnetic resonance imaging and radioisotope cisternography findings. All symptoms completely resolved within a few days after epidural blood patch treatment. Changes in the venous blood distribution led by collapse of the dural sac of the cervical spine in the standing position presumably caused decreased size of the pterygoid venous plexus around the Eustachian tube.

Unsuccessful tracer injection in radionuclide cisternography revisited.

Since cerebrospinal fluid (CSF) leakage is highlighted as a cause of persistent headache, radionuclide cisternography has been increasingly performed in Japan to confirm the disorder, although the limited ability of the examination should be recognized. We present 3 cases in which failure of a tracer injection was strongly suspected. In 2 cases with chronic symptoms, the tracer appeared to be injected into the epidural space, because of irregular initial accumulation of the tracer and lack of diffusion along the CSF cavity. Another is a case with spontaneous CSF leakage confirmed by MRI, and the tracer was thought to be injected into the leaked fluid accumulated in the spinal epidural space. Tracer in the CSF space rapidly disappeared within several hours in all cases. As such cisternographic images may be misdiagnosed as severe CSF leakage, careful interpretation of images in patients especially with no typical MR findings of CSF leakage is necessary. Excessive tracer clearance from the body suggests such technical failure.

[Semi-quantiative RI cisternographic patterns in patients with chronic headache: a resemblance to those of intracranial hypotension syndrome].

Semi-quantitative radionuclide cisternography was performed to evaluate CSF leakage for patients with long-lasting headache and/or neck pain or refractory dizziness which appeared to be related to posture as well as patients with spontaneous intracranial hypotension (SIH). Radioactivity in the whole CSF space was counted and was plotted against time. SIH cases showed rapid decrease of radioactivity in the CSF space. Chronic headache patients were divided into Group I (rapid decrease of activity similarly to those in patients with SIH, to less than 80% at 5h and 40% at 24h), Group II (gradual decrease to less than 40% at 24h), and Group III (activity remained more than 80% at 5h and 40% at 24h). Of 16 patients in Group I, epidural blood patch was attempted in 14, and improvement of symptoms was obtained in 10. In 3 patients who underwent post-treatment RI study, tracer kinetics was normalized. These findings may indicate that some of patients with chronic headache actually have CSF leakage that can be treated with epidural blood patch.

Jugular compression and radionuclide cisternographic patterns in patients with chronic headache.

OBJECTIVE: We investigated the value of the jugular compression test (JCT) in screening patients with chronic headache attributable to persistent cerebrospinal fluid (CSF) leakage. METHODS: Clinical records of 35 consecutive patients who underwent both 111In-diethylenetriamine pentaacetic acid radioisotope (RI) cisternography and JCT were retrospectively analyzed. RESULTS: A strong correlation was seen between JCT and RI cisternographic findings. Most patients who reported a feeling of fullness in the ear, hearing loss or headache during JCT had positive findings on RI cisternograms indicative of CSF leakage. In contrast, no RI study abnormalities were seen in patients reporting no symptoms in JCT. CONCLUSIONS: Among patients complaining of refractory headache and other miscellaneous symptoms, JCT may represent a simple, economic, and reliable technique in the screening of candidates for RI cisternography to evaluate CSF leakage. A subgroup of patients with chronic headache may have persistent CSF leakage.

[Radionuclide cisternography for patients suspected of having intracranial hypotension].

We evaluated radionuclide cisternography for the diagnosis of intracranial hypotension in terms of the rate of appearance of abnormal findings in 23 patients, their correlation with therapy, and the most suitable scanning method and timing for visualization of leakage. During the first hour after injection, dynamic lumbar images or consecutively repeated whole-body images were acquired. Whole body images then were acquired at 1, 5, and 24 hours. Until 5 hours after injection, patients were kept in bed resting. Visualization of the leakage (direct finding) and that of the bladder (indirect finding) were observed in 78.3% (18/23) and 60.9% (14/23), respectively. Leakage was visualized most frequently at 5 hours after injection. There were three cases in which the leakage was only visualized at 24 hours. Therefore, there must be cases that show intermittent CSF leakage. To avoid overlooking these cases, a 24-hour whole-body image is also important. The appropriate procedure of radionuclide cisternography is very important to detect CSF leakage, and our procedure proved to be more effective for detecting the abnormal findings.

Perfusion CT investigation of chronic internal carotid artery occlusion: comparison with SPECT.

This study investigated the usefulness of perfusion computed tomography (CT) for the evaluation of patients with chronic internal carotid artery (ICA) occlusion by comparing the findings with those of iodine-123 iodoamphetamine ([(123)I]IMP) single photon emission computed tomography (SPECT). Twenty five patients with chronic ICA occlusion were investigated on the same day by perfusion CT to measure the cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transient time (MTT), and [(123)I]IMP SPECT to measure the regional CBF, significant correlations were observed between regional CBF measured by SPECT and CBF measured by perfusion CT (r = 0.659, R(2) = 0.434, p < 0.001), regional CBF and CBV (r = -0.406, R(2) = 0.165, p < 0.001) and regional CBF and MTT (r = -0.592, R(2) = 0.350, p < 0.001). Significant correlations were also observed between CBF and CBV (r = -0.153, R(2) = 0.023, p < 0.001), CBF and MTT (r = -0.580, R(2) = 0.337, p < 0.001) and MTT and CBV (r = 0.763, R(2) = 0.582, p < 0.001). Perfusion CT is useful to evaluate the hemodynamic state of patients with chronic major cerebral artery occlusive disorders.

Optimal inversion time for acquiring flow-sensitive alternating inversion recovery images to quantify regional cerebral blood flow.

The purpose of this study was to correlate regional cerebral blood flow (rCBF) measured by I-123-IMP and flow-sensitive alternating inversion recovery (FAIR) studies with different inversion time (TI) values to find out the optimum TI that gives comparable rCBF and images on FAIR study. Nine patients with symptoms and signs of internal carotid or major cerebral arterial stenosis were enrolled in this study. Both I-123-IMP single photon emission computed tomography (SPECT) and FAIR images were acquired in all patients. Single-slice FAIR images (with different TI values) were acquired using a 1.5-T MRI unit. The rCBF was calculated from all I-123-IMP and FAIR images. Receiver operating characteristics (ROC) analysis was performed to detect hypoperfused segments on FAIR images. The rCBF calculated from FAIR and I-123-IMP studies were compared and correlated with each other. The ROC analysis showed no significant differences among the readers or TI values, but a trend of higher sensitivity, specificity, and accuracy was observed with TI of 1400 ms. The rCBF values of FAIR and I-123-IMP studies significantly correlated with each other. The FAIR images with TI value of 1400 ms gave more comparable CBF. A TI value of 1400 ms might be optimum for 1.5-T MR strength to get high quality FAIR images and comparable CBF.

Velocity-coded colour magnetic resonance angiography and perfusion-weighted magnetic resonance imaging for the evaluation of extracranial-to-intracranial arterial bypass surgery.

BACKGROUND AND PURPOSE: Velocity-coded colour magnetic resonance angiography (VCCMRA) and perfusion magnetic resonance imaging (pMRI) were evaluated as methods for investigating the efficacy of extracranial-to-intracranial arterial bypass (EC-IC bypass) by comparing the findings of VCCMRA and those of cerebral angiography and by measuring the improvement ratio after EC-IC bypass by pMRI compared to that by single photon emission computed tomography (SPECT) using the autoradiographic technique. METHODS: Thirteen patients who underwent VCCMRA, angiography, SPECT, and pMRI before and after surgery were analyzed. Findings of VCCMRA were compared to those of angiography. Improvement ratio was calculated compared to the cerebellum for cerebral blood volume, mean transit time (MTT), and regional cerebral blood flow (rCBF) as measured by pMRI and quantitative SPECT. RESULTS: Findings of VCCMRA were in good agreement with those of angiography and clearly showed the direction of bypass flow. No statistically significant correlation was observed between the improvement ratios in CBF in the hemisphere and middle cerebral artery territory on the surgical and non-surgical sides and in rCBF in the same regions of interest (ROIs) (r=-0.574, 0.09). However, a statistically significant correlation was observed between the cerebrovascular reserve capacity (CVRC) in the hemisphere on the surgical side and in MTT in the same ROIs (r=0.955, P<0.001). CONCLUSION: VCCMRA may clearly show the direction of flow in the EC-IC bypass. MIT measured by pMRI may indicate the postoperative state of CVRC. These techniques could replace angiography and positron emission tomography or SPECT in patients undergoing EC-IC bypass.

Quantitative measurement of regional cerebral blood flow with flow-sensitive alternating inversion recovery imaging: comparison with [iodine 123]-iodoamphetamin single photon emission CT.

BACKGROUND AND PURPOSE: Flow-sensitive alternating inversion recovery (FAIR) MR imaging is a technique for depicting cerebral perfusion without contrast enhancement. Our purpose was to determine whether quantification at FAIR imaging can be used to assess regional cerebral blood flow (rCBF) in a manner similar to [iodine 123]-iodoamphetamin ((123)I-IMP) single photon emission CT (SPECT). METHODS: Nine patients with internal carotid or major cerebral arterial stenosis underwent (123)I-IMP SPECT and FAIR imaging (single section, different TIs, 1.5 T) at rest and after acetazolamide (Diamox) stress. FAIR and (123)I-IMP rCBF values were compared and correlated. Receiver operating characteristic analysis was conducted to detect hypoperfused segments on FAIR images. RESULTS: rCBF values of normally perfused segments were 41.53 and 51.91 mL/100 g/min for pre- and post-acetazolamide (123)I-IMP studies, respectively. Corresponding values for pre- and post-acetazolamide FAIR images, respectively, were 46.64 and 59.60 mL/100 g/min with a TI of 1200 milliseconds and 53.23 and 68.17 mL/100 g/min with a TI of 1400 milliseconds. (123)I-IMP and FAIR results were significantly correlated, with both pre- and post-acetazolamide images. Sensitivity (86%) in detecting hypoperfused segments was significantly higher with post-acetazolamide images (TI, 1400 milliseconds), and specificity (82-85%) and accuracy (80-82%) were higher with all pre- and post-acetazolamide images (all TIs). CONCLUSIONS: The significant correlation, high specificity and accuracy in detecting hypoperfused segments, similar increases in flow on both post-acetazolamide images, and absence of the need for contrast enhancement suggest that FAIR imaging, like nuclear medicine study, is complementary to routine MR imaging in the assessment of cerebral perfusion.