Clinical experience of off-pump arch branches preferential reconstruction and whole brain perfusion in the treatment of type A / 中华胸心血管外科杂志

Objective:To introduce the early results of total aortic arch replacement (TAA) without cardiopulmonary bypass (CPB) and without interruption of cerebral blood supply, using the technique of arch branches preferential reconstruction and whole brain perfusion for brain protection.Methods:Between June 2020 and March 2021, a total of 9 Stanford type A aortic dissection patients we performed total arch replacement by using the technique of arch branches preferential reconstruction and whole brain perfusion without cardiopulmonary bypass and without interruption of blood supply to the brain. The method of this reconstruction technique is as follows: A 24F aortic cannula was inserted into the true lumen at the root of the transverse innominate artery (IA) to connect one end of the artery for cardiopulmonary bypass. The access was connected to 14F artery via Y-connector and inserted into IA cavity to maintain blood supply to brain. Without cardiopulmonary bypass, the 10 mm branch of the four branch artificial blood vessel was anastomosed with the innominate artery IA. The perfusion collateral was connected to the second end of the artery of CPB (single pump and double tubes) to continue to supply blood for IA. The left common carotid artery (LCA) and left subclavian artery (LSCA) were reconstructed by the same method. When IA and LCA were anastomosed, the distal blood supply was not interrupted. After the three branches of the aortic arch were anastomosed, we started to turn the machine, then cooled down and blocked the ascending aorta to further complete the operation of the aortic root and arch. During the period of lower body circulatory arrest, the whole brain was perfused with low flow.Results:No intraoperative death or perioperative complications occurred in all patients, and they were discharged smoothly. The cardiopulmonary bypass time was (192.4±58.1) min, the aortic clamping time was (128.3±52.4) min, the lower body circulatory arrest time was (29.1±1.3) min, and the postoperative awake time was (8.2±3.7) h.Conclusion:Off-pump arch branches preferential reconstruction can provide physiological whole brain perfusion, shorten the cardiopulmonary bypass time and aortic occlusion time, and the operation is safe and effective.

Associations between Brain Perfusion and Sleep Disturbance in Patients with Alzheimer's Disease

BACKGROUND AND PURPOSE: Although sleep disturbances are common and considered a major burden for patients with Alzheimer's disease (AD), the fundamental mechanisms underlying the development and maintenance of sleep disturbance in AD patients have yet to be elucidated. The aim of this study was to examine the correlation between regional cerebral blood flow (rCBF) and sleep disturbance in AD patients using technetium-99m hexamethylpropylene amine oxime single-photon emission computed tomography (SPECT). METHODS: A total of 140 AD patients were included in this cross-sectional study. Seventy patients were assigned to the AD with sleep loss (SL) group and the rest were assigned to the AD without SL group. SL was measured using the sleep subscale of the Neuropsychiatric Inventory. A whole-brain voxel-wise analysis of brain SPECT data was conducted to compare the rCBF between the two groups. RESULTS: The two groups did not differ in demographic characteristics, severity of dementia, general cognitive function, and neuropsychiatric symptoms, with the exception of sleep disturbances. The SPECT imaging analysis displayed decreased perfusion in the bilateral inferior frontal gyrus, bilateral temporal pole, and right precentral gyrus in the AD patients with SL group compared with the AD patients without SL group. It also revealed increased perfusion in the right precuneus, right occipital pole, and left middle occipital gyrus in the AD with SL group compared with the AD without SL group. CONCLUSIONS: The AD patients who experienced sleep disturbance had notably decreased perfusion in the frontal and temporal lobes and increased rCBF in the parietal and occipital regions. The findings of this study suggest that functional alterations in these brain areas may be the underlying neural correlates of sleep disturbance in AD patients.

Cerebral Perfusion Changes after Acetyl-L-Carnitine Treatment in Early Alzheimer's Disease Using Single Photon Emission Computed Tomography

BACKGROUND AND PURPOSE: Although acetyl-L-carnitine (ALC) treatment may have beneficial effects on Alzheimer's disease (AD), its underlying neural correlates remain unclear. The purpose of this study was to investigate cerebral perfusion changes after ALC treatment in AD patients using technetium-99m hexamethylpropylene amine oxime single photon emission computed tomography (SPECT). METHODS: A total of 18 patients with early AD were prospectively recruited and treated with ALC at 1.5 g/day for 1.4±0.3 years. At baseline and follow-up, brain SPECT, Mini-Mental State Examination (MMSE), Clinical Dementia Rating (CDR), Global Deterioration Scale (GDS), and Neuropsychiatric Inventory (NPI) were used to assess participants. After ALC administration, changes in brain perfusion, severity of dementia, cognitive performance, and neuropsychiatric disturbances were examined. RESULTS: After ALC administration, changes in scores of MMSE, CDR, GDS, and NPI were not statistically significant (p>0.05). Voxel-wise whole-brain image analysis revealed that perfusion was significantly (p<0.001) increased in the right precuneus whereas perfusion was reduced in the left inferior temporal gyrus (p<0.001), the right middle frontal gyrus (p<0.001), and the right insular cortex (p=0.001) at follow-up. CONCLUSIONS: Although previous studies have suggested that AD patients generally demonstrate progressive deterioration in brain perfusion and clinical symptoms, this study reveals that the perfusion of the precuneus is increased in AD patients after ALC administration and their cognitive and neuropsychiatric symptoms are not aggravated. Further studies are warranted to determine the potential association between perfusion increase in the precuneus and clinical symptoms after ALC treatment in AD patients.

Normal Magnetic Resonance Perfusion Imaging and Atypical Posterior Reversible Encephalopathy Syndrome in Chronic Kidney Disease

BACKGROUND: Posterior reversible encephalopathy syndrome (PRES) is classically characterized by symmetric vasogenic edema in the parietooccipital areas, but may occur at other sites with varying imaging appearances. CASE REPORT: A 55-year old female with chronic kidney disease (CKD) was admitted to the emergency room, presenting with nausea, vomiting and seizure. The initial blood pressure was 145/90 mmHg. Fluid attenuated inversion recovery demonstrated diffuse vasogenic edema in the bilateral cortical and subcortical white matters involving the frontal lobes. Perfusion magnetic resonance imaging (MRP) showed no hyper- or hypoperfusion at blood pressure levels of 140/50 mmHg. A follow-up magnetic resonance imaging at 3 weeks later demonstrated complete resolution of previous lesions. CONCLUSIONS: Earlier reports have demonstrated that PRES can occur in cases of atypical distributions, and features of imaging findings and normotensive settings. It is important to note that PRES is a dynamic process. As a result, we suggest that MRP must be considered in the appropriate temporal framework, to avoid misinterpretation of the other diseases, especially in CKD patients.

Long-Term Efficacy of Memantine in Parkinson' Disease Dementia: An 18-Month Prospective Perfusion Single Photon Emission Computed Tomography Preliminary Study

BACKGROUND AND PURPOSE: Although the treatment efficacy of memantine in Parkinson's disease dementia (PDD) has been reported after several weeks of administration, the long-term effects on brain perfusion and clinical symptoms remain unclear. The current study aimed to follow-up PDD patients after 18 months of memantine treatment using (99m)Tc hexamethylpropylene amine oxime single photon emission computed tomography (SPECT). METHODS: A total of 15 patients with PDD and 11 healthy participants were recruited into this study and they were assessed with brain SPECT, Mini-Mental State Examination (MMSE), Clinical Dementia Rating (CDR), Global Deterioration Scale (GDS), and Neuropsychiatric Inventory (NPI). Differences in regional cerebral blood flow (rCBF) between the two groups were evaluated at baseline. After 18 months of memantine administration, changes in brain perfusion, severity of dementia, cognition, and neuropsychiatric disturbances were examined in the patients with PDD. RESULTS: The PDD group showed hypoperfusion in most of the cortical, subcortical, and cerebellar areas compared to healthy controls at baseline. At the follow-up, changes in rCBF, CDR (p=0.32), sum of box of CDR (p=0.49), MMSE (p=0.61), GDS (p=0.79), and NPI (p=0.23) were not significant in the PDD patients. CONCLUSIONS: Our findings implicate that memantine may delay the progression of brain perfusion deficits and clinical symptoms of PDD in the long term.

Hemodynamic Significance of Internal Carotid or Middle Cerebral Artery Stenosis Detected on Magnetic Resonance Angiography

PURPOSE: We evaluated hemodynamic significance of stenosis on magnetic resonance angiography (MRA) using acetazolamide perfusion single photon emission computed tomography (SPECT). MATERIALS AND METHODS: Of 171 patients, stenosis in internal carotid artery (ICA) and middle cerebral artery (MCA) (ICA-MCA) on MRA and cerebrovascular reserve (CVR) of MCA territory on SPECT was measured using quantification and a 3-grade system. Stenosis and CVR grades were compared with each other, and their prognostic value for subsequent stroke was evaluated. RESULTS: Of 342 ICA-MCA, 151 (44%) presented stenosis on MRA; grade 1 in 69 (20%) and grade 2 in 82 (24%) cases. Decreased CVR was observed in 9% of grade 0 stenosis, 25% of grade 1, and 35% of grade 2. The average CVR of grade 0 was significantly different from grade 1 (p<0.001) and grade 2 stenosis (p=0.007). In quantitative analysis, average CVR index was -0.56+/-7.91 in grade 0, -1.81+/-6.66 in grade 1 and -1.18+/-5.88 in grade 2 stenosis. Agreement between stenosis and CVR grades was fair in patients with lateralizing and non-lateralizing symptoms (kappa=0.230 and 0.346). Of the factors tested, both MRA and CVR were not significant prognostic factors (p=0.104 and 0.988, respectively), whereas hypertension and renal disease were significant factors (p<0.05, respectively). CONCLUSION: A considerable proportion of ICA-MCA stenosis detected on MRA does not cause CVR impairment despite a fair correlation between them. Thus, hemodynamic state needs to be assessed for evaluating significance of stenosis, particularly in asymptomatic patients.

The feasibility study of CT perfusion imaging of rabbit brain with 70 kV tube voltage / 中华放射医学与防护杂志

Objective To evaluate the feasibility of low dose CT perfusion imaging of brain using the tube voltage of 70 kV.Methods Twenty New Zealand white rabbits underwent cerebral CT perfusion imaging with tube voltage 70 and 80 kV separately,and the interval between two scans was 24 h.The effective dosage (E),cerebral perfusion parameters (CBF,CBV,MTT) and image quality indicator (SNR) of middle cerebral artery of each protocol were acquired and compared statistically.Results The effective dosage of70 kV group was 1.91 mSv,34.8％ lower than that of 80 kV group with the dose of 2.93 mSv.There were no significant differences between the cerebral perfusion parameters acquired at different corresponding ROI.SNR of 70 kV group and 80 kV group were (23.15 ± 5.98) and (21.23 ±9.18) with no significantly statistical difference.Conclusions The effective dosage of 70 kV cerebral CT perfusion imaging could be dramatically reduced with no significant influence on the results of perfusion parameters and image quality.

Application of whole-brain CT perfusion combined with ankle-brachial index in acute cerebral ischemia / 第二军医大学学报

Objective To investigate the clinical value of whole-brain CT perfusion combined with ankle-brachial index (ABI) in patients with acute cerebral ischemia. Methods A total of 105 patients who were suspected of having cerebral ischemia were selected in this study,including 33 patients in the abnormalABI group and 72 patients in normal ABI group. Examination by a 320-detectorrow whole-brain computed tomography (CT) scan with CT angiography (CTA) and CT perfusion was given to all the patientswith stable symptoms. The perfusion parameters,including cerebral blood flow (CBF),cerebral blood volume (CBV),mean transit time (MTT),time to peak (TTP) and delay time,were obtained. The brain perfusion images wereevaluated by two experienced physicians,andthen the positive predictive value,negative predictive value,sensitivity and specificity of ABI in predicting brain CT perfusion abnormalities were calculated. Results Sixty-eight patients showed brain CT perfusion abnormalities,manifested as prolonged MTT and TTP,increased,normal or reduced CBV,and normal or reduced CBF. The 68 patients included 25 with abnormal ABI and 43 with normal ABI. The rate of positive CT perfusion in the abnormal ABI group (75. 8%,25/33) was significantly higher than that in the normal ABI group (59. 7%,43/72; P = 0. 039); the relative MTT and the relative TTP in the abnormal ABI group were also significantly longer than those in the normal ABI group (P<0. 05). The positive predictive value,negative predictive value,sensitivity,and specificity of ABI predicted brain CT perfusion abnormalities were 75. 8%,40. 3%,36. 8%,and 78. 4%,respectively. Conclusion Whole-brain CT perfusion can accurately evaluate the hemodynamic changes at an early stage; simple ABI examination has certain predictive value for brain perfusion abnormalities; and the combination of them may facilitate the earlier detection and treatment of cerebral ischemia.

Brain SPECT in mesial temporal lobe epilepsy: comparison between visual analysis and SPM / SPECT cerebral na epilepsia de lobo temporal mesial: comparação entre análise visual e SPM

OBJECTIVE: To compare the accuracy of SPM and visual analysis of brain SPECT in patients with mesial temporal lobe epilepsy (MTLE). METHOD: Interictal and ictal SPECTs of 22 patients with MTLE were performed. Visual analysis were performed in interictal (VISUAL(inter)) and ictal (VISUAL(ictal/inter)) studies. SPM analysis consisted of comparing interictal (SPM(inter)) and ictal SPECTs (SPM(ictal)) of each patient to control group and by comparing perfusion of temporal lobes in ictal and interictal studies among themselves (SPM(ictal/inter)). RESULTS: For detection of the epileptogenic focus, the sensitivities were as follows: VISUAL(inter)=68 percent; VISUAL(ictal/inter)=100 percent; SPM(inter)=45 percent; SPM(ictal)=64 percent and SPM(ictal/inter)=77 percent. SPM was able to detect more areas of hyperperfusion and hypoperfusion. CONCLUSION: SPM did not improve the sensitivity to detect epileptogenic focus. However, SPM detected different regions of hypoperfusion and hyperperfusion and is therefore a helpful tool for better understand pathophysiology of seizures in MTLE.

OBJETIVO: Comparar a acurácia do SPM com a análise visual na detecção do foco epileptogênico e alterações perfusionais à distância no SPECT cerebral. MÉTODO: Foram realizados os SPECTs ictal e interictal de 22 pacientes com epilepsia de lobo temporal mesial (ELTM). A análise visual foi realizada nos estudos interictal (VISUAL(inter)) e ictal (VISUAL(ictal/inter)). Na análise com SPM foi comparado o estudo interictal (SPM(inter)) e ictal (SPM(ictal)) de cada paciente com o grupo controle e comparou-se a perfusão dos lobos temporais entre os estudos ictal e interictal (SPM(ictal/inter)). RESULTADOS: Para a detecção do foco epileptogênico, as sensibilidades foram as seguintes: VISUAL(inter)=68 por cento; VISUAL(ictal/inter)=100 por cento; SPM(inter)=45 por cento; SPM(ictal)=64 por cento and SPM(ictal/inter)=77 por cento. O SPM foi capaz de detectar mais áreas de hiperperfusão e hipoperfusão. CONCLUSÃO: O SPM não aumentou a sensibilidade na detecção do foco epileptogênico. Entretanto, o SPM detectou diferentes regiões de hipoperfusão e hiperperfusão e portanto, ele pode ser uma ferramenta de ajuda para se melhor entender a patofisiologia das crises na ELTM.

Comparison of clinical application of different brain perfusion imaging techniques / 中国介入影像与治疗学

In the past few years, many techniques were used to study brain perfusion imaging;each of them has its own advantages and disadvantages. The principle, specification, clinical application, contradistinction and the current research situation of these techniques were reviewed in this article.

Application of contrast-enhanced ultrasound in brain perfusion / 中国医学影像技术

Ultrasound brain perfusion imaging can evaluate brain perfusion in normal and pathological conditions. After basilar stent implantation, contrast-enhanced ultrasound (CEUS) can show normal visualization of color flow within the stent and provide essential functional information by evaluation of blood flow velocities. Furthermore, CEUS can estimate the volume of brain hemorrhage and readily identify residual tumor. CEUS can be used in thrombolysis, and will be applied in cerebral trauma. The value of CEUS in brain perfusion imaging was reviewed in this article.

Characteristics of Brain Perfusion in Patients of Parkinson's Disease / 핵의학분자영상

PURPOSE: It was well known that cerebral blood perfusion is normal or diffusely decreased in the majority of patients with Parkinson's disease (PD). Actually we interpreted brain perfusion SPECT images of PD patients in the clinical situation, we observed various cerebral perfusion patterns in patients with PD. So we performed brain perfusion SPECT to know the brain perfusion patterns of PD patients and the difference of perfusion patterns according to the sex and the age. Also we classified PD patients into small groups based on the brain perfusion pattern. METHODS AND MATERIALS: Two hundred nineteen patients (M: 70, F: 149, mean age: 62.9+/-6.9 y/o) who were diagnosed as PD without dementia clinically and 55 patients (M: 15, F: 40, mean age: 61.4+/-9.2 y/o) as normal controls who had no past illness history were performed (99m)Tc-HMPAO brain perfusion SPECT and neuropsychological test. RESULTS: At first, we compared all patients with PD and normal controls. Brain perfusion in left inferior frontal gyrus, left insula, left transverse temporal gyrus, left inferior parietal lobule, left superior parietal lobule, right precuneus, right caudate tail were lower in patients with PD than normal controls. Secondly, we compared male and female patients with PD and normal controls, respectively. Brain perfusion SPECT showed more decreased cerebral perfusion in left hemisphere than right side in both male and female patients compared to normal controls. And there was larger hypoperfusion area in female patients compared with male. Thirdly, we classified patients with PD and normal controls into 4 groups according to the age and compared brain perfusion respectively. In patient below fifties, brain perfusion in both occipitoparietal and left temporal lobe were lower in PD group. As the patients with PD grew older, hypoperfusion area were shown in both frontal, temporal and limbic lobes. Fourthly, We were able to divide patients into small groups based on cerebral perfusion pattern. There was normal cerebral blood perfusion in 32 (14.7%) of 219 patients with PD, decreased perfusion on the frontal lobe in 45 patients (20.6%), the temporal lobe in 38 patients (17.4%), the parietal lobe in 39 patients (17.9%), the occipital lobe in 40 patients (18.3%), diffuse area in 14 patients (6.4%) and unclassified in 10 patients (4.6%). Fifthly, we compared the results of the neuropsychological test and cerebral perfusion pattern. There was no correlation between two tests except visuospatial function. CONCLUSION: Various perfusion state were found in patients with PD according to the age and sex. Also we were able to classify perfusion state into several groups and compare the neuropsychological test with cerebral perfusion.

Imaging of the Ischemic Penumbra in Acute Stroke

One of the main reasons for the soaring interest in acute ischemic stroke among radiologists is the advent of new magnetic resonance techniques such as diffusion-weighted imaging. This new modality has prompted us to seek a better understanding of the pathophysiologic mechanisms of cerebral ischemia/infarction. The ischemic penumbra is an important concept and tissue region because this is the target of various recanalization treatments during the acute phase of stroke. In this context, it is high time for a thorough review of the concept, especially from the imaging point of view.

Assessment of Tissue Viability Using Diffusion- and Perfusion-Weighted MRI in Hyperacute Stroke

OBJECTIVE: The aim of this study was to investigate the relationship between the diffusion and perfusion parameters in hyperacute infarction, and we wanted to determine the viability threshold for the ischemic penumbra using diffusion- and perfusion-weighted imaging (DWI and PWI, respectively). MATERIALS AND METHODS: Both DWI and PWI were performed within six hours from the onset of symptoms for 12 patients who had suffered from acute stroke. Three regions of interest (ROIs) were identified: ROI 1 was the initial lesion on DWI; ROI 2 was the DWI/PWI mismatch area (the penumbra) that progressed onward to the infarct; and ROI 3 was the mismatch area that recovered to normal on the follow-up scans. The ratios of apparent diffusion coefficient (ADC), the relative cerebral blood volume (rCBV), and the time to peak (TTP) were calculated as the lesions' ROIs divided by the contralateral mirror ROIs, and these values were then correlated with each other. The viability threshold was determined by using the receiver operating characteristic (ROC) curves. RESULTS: For all three ROIs, the ADC ratios had significant linear correlation with the TTP ratios (p < 0.001), but not with the rCBV ratios (p = 0.280). There was no significant difference for the ADC and rCBV ratios within the ROIs. The mean TTP ratio/TTP delay between the penumbras' two ROIs showed a significant statistical difference (p < 0.001). The cutoff value between ROI 2 and ROI 3, as the viability threshold, was a TTP ratio of 1.29 (with a sensitivity and specificity of 86% and 73%, respectively) and a TTP delay of 7.8 sec (with a sensitivity and specificity of 84% and 72%, respectively). CONCLUSION: Determining the viability thresholds for the TTP ratio/delay on the PWI may be helpful for selecting those patients who would benefit from the various therapeutic interventions that can be used during the acute phase of ischemic stroke.

Development of PC-based Software to Analyze Dynamic Cerebral Perfusion CT Quantitatively and to Reformat Perfusion Maps

PURPOSE: The purpose of this study was to develop PC-based perfusion software using Microsoft Windows. This software was developed to reformat perfusion maps including CBV (Cerebral Blood Volume), MTT (Mean Transit Time), and CBF (Cerebral Blood Flow) maps and to analyze perfusion quantitatively. MATERIALS AND METHODS: Windows-based perfusion software was developed using IDL (Interactive Data Language) as the development tool. The perfusion software was written to load the source image from dynamic first-pass cerebral perfusion CT and to reformat perfusion maps. Mean perfusion values in gray matter and white matter were calculated and compared to previously calculated data reported in literature. RESULTS: This software reformatted first pass perfusion maps in a user-friendly PC and calculated CBV, MTT, and CBF values. The values were within the normal range of the mean values when compared to previous studies. CONCLUSION: CT perfusion maps and perfusion values can be obtained by using the newly developed PC-based perfusion software. Further study is needed to achieve more precise values. However, we believe that in the future, this program may be used in various clinical settings.

Usefulness of CT Perfusion Imaging in Adult Moyamoya Disease

PURPOSE: The purpose of this study was to evaluate the role of perfusion CT in adult moyamoya disease. MATERIALS AND METHODS: The study population consisted of 13 adult moyamoya patients (10 women and 3 men, mean age: 40.4 years) and 11 age-matched normal controls (5 men and 6 women, mean age: 43 years). We retrospectively assessed the perfusion CT scan both visually and by a quantitative regional analysis, and we assessed the relationship between the perfusion CT scan findings and the angiographic findings. RESULTS: The mean relative cerebral blood volume (rCBV) values in moyamoya patients were 8.0% for the MCA area, 6.4% for the PCA area, and 7.7% for the basal ganglia. The rCBV values in the patients were higher than those in the control group with statistical significance (p<0.0001). The time to peak enhancement (TTP) values of the MCA area and the basal ganglia were delayed more than those in the controls; this was statistically significant (p<0.05). Moderate correlation was found between the rCBV in the basal ganglia area and angiographic stage of the basal moyamoya vessels. CONCLUSION:Perfusion CT demonstrates a statistically significant increase in rCBV in the MCA, PCA and basal ganglia areas and the TTP in the MCA and basal ganglia areas in patients with moyamoya disease. The visual brain perfusion patterns correlate with the extent and severity of the basal moyamoya vessels.

Acute Cerebral Infarction in a Rabbit Model: Perfusion and Diffusion MR Imaging

PURPOSE: The present study was undertaken to evaluate the usefulness of cerebral diffusion (DWI) and perfusion MR imaging (PWI) in rabbit models with hyperacute cerebral ischemic infarction. MATERIALS AND METHODS: Experimental cerebral infarction were induced by direct injection of mixture of Histoacryl glue, lipiodol, and tungsten powder into the internal cerebral artery of 6 New-Zealand white rabbits, and they underwent conventional T1 and T2 weighted MR imaging, DWI, and PWI within 1 hour after the occlusion of internal cerebral artery. The PWI scan for each rabbit was obtained at the level of lateral ventricle and 1cm cranial to the basal ganglia. By postprocessing using special imaging software, perfusion images including cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) maps were obtained. The detection of infarcted lesion were evaluated on both perfusion maps and DWI. MTT difference time were measured in the perfusion defect lesion and symmetric contralateral normal cerebral hemisphere. RESULTS: In all rabbits, there was no abnormal signal intensity on T2WI. But on DWI, abnormal high signal intensity, suggesting cerebral infarction, were detected in all rabbits. PWI (rCBV, CBF, and MTT map) also showed perfusion defect in all rabbits. In four rabbits, the calculated square of perfusion defect in MTT map is larger than that of CBF map and in two rabbits, the calculated size of perfusion defect in MTT map and CBF map is same. Any rabbits do not show larger perfusion defect on CBF map than MTT map. In comparison between CBF map and DWI, 3 rabbits show larger square of lesion on CBF map than on DWI. The others shows same square of lesion on both technique. The size of lesion shown in 6 MTT map were larger than DWI. In three cases, the size of lesion shown in CBF map is equal to DWI. But these were smaller than MTT map. The calculated square of lesion in CBF map, equal to that of DWI and smaller than MTT map was three. And in one case, the calculated square of perfusion defect in MTT map was largest, and that of DWI was smallest. CONCLUSION: DWI and PWI may be useful in diagnosing hyperacute cerebral ischemic infarction and in evaluating the cerebral hemodynamics in the rabbits.

Perfusion MR Imaging: Clinical Utility for the Differential Diagnosis of Various Brain Tumors

OBJECTIVE: To determine the utility of perfusion MR imaging in the differential diagnosis of brain tumors. MATERIALS AND METHODS: Fifty-seven patients with pathologically proven brain tumors (21 high-grade gliomas, 8 low-grade gliomas, 8 lymphomas, 6 hemangioblastomas, 7 metastases, and 7 various other tumors) were included in this study. Relative cerebral blood volume (rCBV) and time-to-peak (TTP) ratios were quantitatively analyzed and the rCBV grade of each tumor was also visually assessed on an rCBV map. RESULTS: The highest rCBV ratios were seen in hemangioblastomas, followed by high-grade gliomas, metastases, low-grade gliomas, and lymphomas. There was no significant difference in TTP ratios between each tumor group (p<0.05). At visual assessment, rCBV was high in 17 (81%) of 21 high-grade gliomas and in 4 (50%) of 8 low-grade gliomas. Hemangioblastomas showed the highest rCBV and lymphomas the lowest. CONCLUSION: Perfusion MR imaging may be helpful in the differentiation of thevarious solid tumors found in the brain, and in assessing the grade of the various glial tumors occurring there.

Perfusion MR Imaging of Cerebral Gliomas: Comparison with Histologic Tumor Grade

PURPOSE: Our purpose was to compare maximum relative cerebral blood volume (rCBV) with histologic grade of cerebral gliomas. MATERIALS AND METHODS: First-pass perfusion MR imaging was performed preoperatively in 16 patients with pathologically proven cerebral gliomas (7 glioblastoma, 2 anaplastic astrocytoma, 1 anaplastic oligo-dendroglioma, 5 low-grade astrocytoma, and 1 low-grade oligodendroglioma). Maximum rCBV was com-pared with histologic diagnosis and grade of the tumor. RESULTS: Maximum rCBVs of glioblastomas were in the range of 433%-1330% (average, 790%), as compared with those of contra-lateral normal white matters. Maximum rCBVs of two non-enhancing anaplastic astrocytomas were 66% and 284%, respectively. Maximum rCBV of one well-enhancing anaplastic oligodendroglioma was 502%. Maximum rCBVs of low-grade astrocytomas were in the range of 80%-369% (average, 202%). Maximum rCBV of one low-grade oligodendroglioma was 1450%, even higher than those of glioblastomas. CONCLUSION: Maximum rCBV was higher in glioblastoma than in low-grade astrocytoma without overlap-ping. However, there was no difference of maximum rCBV between non-enhancing anaplastic astrocytoma and low-grade astrocftoma.