Differences In Perfusion Values Research Articles

Evaluation of Brain Perfusion with Radionuclide Imaging in Dementia Patients

Objective: This study aims to evaluate the perfusion in the affected brain lobes with radionuclide imaging in patients with dementia and to contribute to the literature by determining the relationship between the degree of dementia. Methods: In this retrospective study, 44 adult patients were included. The mean age of the patients was 73 (57-87). Twenty-three (52.3%) of these were female. All patients underwent mini-mental state test, neurological examinations and radionuclide brain perfusion imaging. The areas of interest of the frontal, parietal, temporal, and occipital lobes and the cerebellum were drawn, respectively, and the cerebellum ratios of the relevant lobes were compared. In this way, brain perfusion index values of lobes were obtained. Results: Brain perfusion in group 1 was higher than in other groups. Groups were also compared in pairs. There was no significant difference in perfusion values in the occipital lobe. There was a significant difference in perfusion between groups 1 and 2 in lobes other than the occipital lobe. This was also the case for Groups 1 and 3. When group 2 with early dementia symptoms, and group 3 with moderate dementia were compared, there was a significant difference between the perfusion values of only the right and left frontal lobes. Conclusion: Early diagnosis is very important in progressive dementia. Clinical tests are successfully applied to categorize patients. Evaluation of brain perfusion and metabolism with functional radionuclide imaging is significant in guiding the treatment and evaluating the success of the treatment.

Evaluation of Hemodynamics Before and After Revascularization in Hemorrhagic Moyamoya Disease: A Computed Tomography Perfusion Imaging Case Study

To explore the feasibility of computed tomography perfusion imaging (CTP) for evaluating hemodynamics in hemorrhagic moyamoya disease (MMD). The retrospective analysis included 25 patients with hemorrhagic MMD who underwent brain CTP examination. Two experienced radiologists manually delineated regions of interest (ROIs) in the bilateral frontal lobe, temporal lobe, brain tissue adjacent to the hemorrhagic foci, and brainstem as a control region. The perfusion values for all ROIs were extracted, including cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time to peak (TTP). Subsequently, the differences in perfusion values for different brain tissues were compared between the hemorrhagic side and the nonhemorrhagic side. For patients who underwent revascularization surgery, differences in perfusion values from before to after surgery were determined in brain tissues on the ipsilateral side. CBF in the area around the hematoma and the lateral temporal lobe on the hemorrhage hemisphere was lower than that on the contralateral side, whereas TTP and MTT were higher. Among the 14 patients who underwent revascularization, CBF and CBV in the postoperative temporal lobes were higher than the preoperative values, whereas TTP and MTT were lower. CBF and CBV in the frontal lobe were higher after the operation. Hemorrhagic MMD results in cerebral ischemia, and CTP could be used to localize such ischemic brain tissue and objectively evaluate the changes in cerebral hemodynamics with revascularization.

Correlation between pathologic features and perfusion CT of renal cancer: a feasibility study

The computerized tomography with perfusion technique (pCT) has proved to have some potentialities in the oncologic field as a possible tool to identify neoangiogenesis in vivo. The purpose of the present job is to test the correlations existing between perfusion data and pathologic features in the evaluation of vascularization in kidney cancer. 6 patients with clinical diagnosis of renal tumor awaiting surgical treatment underwent preoperatively pCT scans. Axial images encompassing the greatest diameter of the cancer were compared with the respective histological sections. A correlation between tumor histological subtype and perfusion index was observed and shown. Moreover, clear cell RCC of different Fuhrman grades showed statistically significant differences in perfusion values (T test). Specifically, high perfusion indexes were associated with high density of microvessels with abnormal architecture at the microscopic evaluation of tumor specimen. Conversely, lower perfusion index were detected in tumors with lower microvascular density. pCT scans can provide significant data on tumor angiogenesis and, eventually, suggest tumor histological subtype. The possibility of identifying preoperatively tumor histotype can be of particular relevance in patients with small renal tumors, suitable for minimally-invasive surgery or active surveillance program.

Feasibility of simultaneous PET-MR perfusion using a novel cardiac perfusion phantom

BackgroundPET-MR scanners are beginning to be employed for quantitative myocardial perfusion imaging. In order to examine simultaneous perfusion calculations, this work describes a feasibility study of simultaneous PET-MR of gadolinium-based contrast agent (GBCA) and PET radiotracer in a novel cardiac perfusion phantom.Results[18F]F− and GBCA were injected simultaneously into a cardiac phantom using a range of ground-truth myocardial perfusion rates of 1 to 5 ml/g/min. PET quantification of K1 (ml/g/min) was performed using a single tissue compartment model. MR perfusion was calculated using a model-independent signal deconvolution technique. PET and MR signal traces from the phantom aorta and myocardial sections show true simultaneous PET and MR arterial input functions (AIF) and myocardial uptake respectively at each perfusion rate. Calculation of perfusion parameters showed both K1 and h(t = 0) (PET and MR perfusion parameters respectively) to be linearly related with the ground truth perfusion rate (PT), and also linearly related to each other (R2 = 0.99). The highest difference in perfusion values between K1 and PT was 16% at 1 ml/g/min, and the mean difference for all other perfusion rates was <3%.ConclusionsThe perfusion phantom allows accurate and reproducible simulation of the myocardial kinetics for simultaneous PET-MR imaging, and may find use in protocol design and development of PET-MR based quantification techniques and direct comparison of quantification of the two modalities.

Interleaving cerebral CT perfusion with neck CT angiography part I. Proof of concept and accuracy of cerebral perfusion values

ObjectivesWe present a novel One-Step-Stroke protocol for wide-detector CT scanners that interleaves cerebral CTP with volumetric neck CTA (vCTA). We evaluate whether the resulting time gap in CTP affects the accuracy of CTP values.MethodsCerebral CTP maps were retrospectively obtained from 20 patients with suspicion of acute ischemic stroke and served as the reference standard. To simulate a 4 s gap for interleaving CTP with vCTA, we eliminated one acquisition at various time points of CTP starting from the bolus-arrival-time(BAT). Optimal timing of the vCTA was evaluated. At the time point with least errors, we evaluated elimination of a second time point (6 s gap).ResultsMean absolute percentage errors of all perfusion values remained below 10 % in all patients when eliminating any one time point in the CTP sequence starting from the BAT. Acquiring the vCTA 2 s after reaching a threshold of 70HU resulted in the lowest errors (mean <3.0 %). Eliminating a second time point still resulted in mean errors <3.5 %. CBF/CBV showed no significant differences in perfusion values except MTT. However, the percentage errors were always below 10 % compared to the original protocol.ConclusionInterleaving cerebral CTP with neck CTA is feasible with minor effects on the perfusion values.Key Points• Removing a single CTP acquisition has minor effects on calculated perfusion values• Calculated perfusion values errors depend on timing of skipping a CTP acquisition• Qualitative evaluation of CTP was not influenced by removing two time points• Neck CTA is optimally timed in the upslope of arterial enhancement

Two-Dimensional Perfusion Angiography of the Foot

Purpose: To report the feasibility, technical considerations, and initial results of 2-dimensional (2D) perfusion angiography of the foot before and after endovascular interventions. Methods: A retrospective single-center study involved 21 patients (mean age 73.4±10.5 years; 14 men) with severe peripheral vascular disease [Fontaine stage III (n=10) or IV (n=14)] who underwent lower limb digital subtraction angiography (DSA) prior to and following endovascular treatment of above- and/or below-knee lesions. A standardized contrast administration protocol (15 mL iodixanol 320 mg I/mL at 3 mL/s via a 5/6-F antegrade sheath) was applied during DSA using a 2D perfusion–enabled image intensifier. Representative hindfoot and forefoot regions of interest were analyzed, and representative numeric density values [time to peak (TTP), peak density value (PDV), and area under the (time-density) curve (AUC)] were calculated using 2D perfusion–enabled angiographic software to assess foot perfusion. Values were compared before and after angioplasty and by level of treatment (above or below knee). The parameters were correlated with disease severity (stenosis vs occlusion) and symptom level (Fontaine stage). Results: A clinically significant improvement (29.4%) in the AUC was noted following angioplasty, reaching statistical significance within the hindfoot (p=0.03). No significant change in TTP or PDV was detected following angioplasty. Foot movement remained problematic when measuring time-density values. No statistical difference in perfusion values was appreciable between above- and below-knee angioplasty. Conclusion: Two-dimensional perfusion angiography of the foot allows quantitative evaluation using various density values with potential benefit for treatment planning and technical outcome analysis. Methodical restrictions currently remain, mainly regarding patient movement.

Repeatability, Reproducibility and Standardisation of a Laser Doppler Imaging Technique for the Evaluation of Normal Mouse Hindlimb Perfusion

BackgroundPreclinical perfusion studies are useful for the improvement of diagnosis and therapy in dermatologic, cardiovascular and rheumatic human diseases. The Laser Doppler Perfusion Imaging (LDPI) technique has been used to evaluate superficial alterations of the skin microcirculation in surgically induced murine hindlimb ischemia. We assessed the reproducibility and the accuracy of LDPI acquisitions and identified several critical factors that could affect LDPI measurements in mice.MethodsTwenty mice were analysed. Statistical standardisation and a repeatability and reproducibility analysis were performed on mouse perfusion signals with respect to differences in body temperature, the presence or absence of hair, the type of anaesthesia used for LDPI measurements and the position of the mouse body.ResultsWe found excellent correlations among measurements made by the same operator (i.e., repeatability) under the same experimental conditions and by two different operators (i.e., reproducibility). A Bland-Altman analysis showed the absence of bias in repeatability (p = 0.29) or reproducibility (p = 0.89). The limits of agreement for repeatability were –0.357 and –0.033, and for reproducibility, they were –0.270 and 0.238. Significant differences in perfusion values were observed in different experimental groups.ConclusionsDifferent experimental conditions must be considered as a starting point for the evaluation of new drugs and strategic therapies.

Assessment of Tumor Vascularization in Pancreatic Adenocarcinoma Using 128-Slice Perfusion Computed Tomography Imaging

Computed tomography (CT) perfusion studies can provide valuable information regarding tumor vascularization. We report on a study assessing CT perfusion characteristics in the normal pancreas and in patients with pancreatic adenocarcinoma. Twenty healthy subjects and 20 patients with histologically confirmed pancreatic adenocarcinoma were included in the study after written informed consent and approval by our institutional review board. All subjects underwent perfusion CT imaging of the pancreas using 128-slice dual-source CT. The scanning sequence included 18 scans. Parametric maps of blood volume (BV), blood flow (BF), and permeability surface area product (PS) were generated and compared with density measurements. In normal pancreas, no significant difference in perfusion values was observed between head, body, and tail of the pancreas. Mean organ values were 76.76 (SD, 15.6) mL/100 g/min, 15.80 (SD, 2.40) mL/100 g, and 27.74 (SD, 16.8) mL/100 g/min for BF, BV, and PS, respectively. Compared with the normal pancreas, a 60% reduction in BF and BV was observed in the tumor tissue. Perfusion values gradually increased toward the tumor rim. Necrotic tumor areas were identified in 25% of patients. No significant differences were observed when comparing normal pancreas and healthy pancreatic tissue in adenocarcinoma patients. The feasibility of whole-tumor perfusion imaging using 128-slice CT was demonstrated in patients with pancreatic adenocarcinoma. Perfusion CT provides additional information compared with image assessment based on density measurements (Hounsfield units) and allows noninvasive assessment of vascularization in the tumor tissue.

Correlation between pathologic features and perfusion CT of renal cancer: A feasibility study

Objectives The computerized tomography with perfusion technique (pCT) has proved to have some potentialities in the oncologic field as a possible tool to identify neoangiogenesis in vivo. The purpose of the present job is to test the correlations existing between perfusion data and pathologic features in the evaluation of vascularization in kidney cancer. Methods 6 patients with clinical diagnosis of renal tumor awaiting surgical treatment underwent preoperatively pCT scans. Axial images encompassing the greatest diameter of the cancer were compared with the respective histological sections. Results A correlation between tumor histological subtype and perfusion index was observed and shown. Moreover, clear cell RCC of different Fuhrman grades showed statistically significant differences in perfusion values (T test). Specifically, high perfusion indexes were associated with high density of microvessels with abnormal architecture at the microscopic evaluation of tumor specimen. Conversely, lower perfusion index were detected in tumors with lower microvascular density. Conclusions pCT scans can provide significant data on tumor angiogenesis and, eventually, suggest tumor histological subtype. The possibility of identifying preoperatively tumor histotype can be of particular relevance in patients with small renal tumors, suitable for minimally-invasive surgery or active surveillance program.

Relationship between vasospasm, cerebral perfusion, and delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

IntroductionVasospasm after aneurysmal subarachnoid hemorrhage (SAH) is thought to cause ischemia. To evaluate the contribution of vasospasm to delayed cerebral ischemia (DCI), we investigated the effect of vasospasm on cerebral perfusion and the relationship of vasospasm with DCI.MethodsWe studied 37 consecutive SAH patients with CT angiography (CTA) and CT perfusion (CTP) on admission and within 14 days after admission or at time of clinical deterioration. CTP values (cerebral blood volume, cerebral blood flow (CBF) and mean transit time), degree of vasospasm on CTA, and occurrence of DCI were recorded. Vasospasm was categorized as follows: no spasm (0–25% decrease in vessel diameter), moderate spasm (25–50% decrease), and severe spasm (>50% decrease). The correspondence of the flow territory of the most spastic vessel with the least perfused region was evaluated, and differences in perfusion values and occurrence of DCI between degrees of vasospasm were calculated with 95% confidence intervals (95% CI).ResultsFourteen patients had no vasospasm, 16 were moderate, and seven were severe. In 65% of patients with spasm, the flow territory of the most spastic vessel corresponded with the least perfused region. There was significant CBF (milliliters per 100 g per minute) difference (−21.3; 95% CI, −37 ↔ −5.3) between flow territories of severe and no vasospasm. Four of seven patients with severe, six of 16 with moderate, and three of 14 patients with no vasospasm had DCI.ConclusionVasospasm decreases cerebral perfusion, but corresponds with the least perfused region in only two thirds of our patients. Furthermore, almost half of patients with severe vasospasm do not have DCI. Thus, although severe vasospasm can decrease perfusion, it may not result in DCI.

Pattern of regional cerebral blood-flow changes induced by acute heroin administration – a perfusion MRI study

Purpose Although both the subjective and physiological effects of abused psychotropic substances have been characterized, less is known about their effects on brain function. We examined the actions of intravenous diacetylmorphine (heroin), the most widely abused opioid, on regional cerebral blood flow (rCBF), as assessed by perfusion-weighted MR imaging (PWI) in a double-blind and placebo-controlled setting. Material and Methods Eight male subjects dependent of diacetylmorphine (mean age 36 years, range: 26 to 44 years), who had participated in a clinical diacetylmorphine maintenance program, underwent PWI with gadolinium injection. At two sessions separated by 2–7 days, the participants were examined 80 s after intravenous administration of either diacetylmorphine or saline. rCBF in four regions of interest (amygdala, vermis of the cerebellum, anterior cingulated cortex and thalamus) was compared with heroin versus placebo. Results In the cerebellum, thalamus and cingulated cortex, there were no significant differences in perfusion values between diacetylmorphine and placebo. In the amygdala, perfusion values were 0.8 ± 0.4 and 0.5 ± 0.2 on the left, and 0.9 ± 0.4 and 0.6 ± 0.3 on the right, with diacetylmorphine and with placebo, respectively ( t-test results were P = 0.044 and P = 0.033 on the left and right sides, respectively). Other differences in perfusion values between the drug and placebo did not reach statistical significance. Conclusion Perfusion MRI demonstrated differences in brain hemodynamics induced by drug intake.

Assessment of Tissue Viability in Hyperacute Infarction with Using the Diffusion- and Perfusion-weighted Images

Purpose: The presence of a perfusion-diffusion mismatch is a useful indicator for predicting the progression of acute cerebral infarction. However, not all the area of the perfusion-diffusion mismatch progresses to infarction and a large proportion survives with hypoperfusion. The purpose of this study was to assess 1) whether tissue viability can be predicted using quantitative perfusion values and 2) whether there is correlation between the perfusion value and the time that elapsed after the onset of symptoms. Materials and Methods: Twenty-two patients with acute infarction in the middle cerebral artery territory within 12 hours after symptom onset were included in this study. We excluded those patients in whom thrombolysis was attempted or the lesion volume was less than 5 mL. Patients without perfusion-diffusion mismatch on the mean transit time (MTT) map were also excluded. We categorized the ischemic lesions into 3 areas: 1) the initial infarction, 2) the area that progressed to infarction, and 3) the hypoperfused but surviving area, based on the initial and follow up diffusion-weighted images and initial mean transit time (MTT) map. We obtained the relative cerebral blood volume (rCBV), the cerebral blood flow (rCBF) and the MTT in each area by comparing to the contralateral normal area. Statistical analysis was performed using one-way ANOVA to test whether there was a difference in perfusion values between each area. The threshold value was calculated between areas 2 and 3 using the receiver operating characteristics curve. We analyzed the correlation between the perfusion values of each area and the time that elapsed after the inset of symptoms. Results: The perfusion values among each region were significantly different on the rCBV, rCBF and MTT maps. Between regions 2 and 3, the rCBV and rCBF maps showed a significant difference (Bonferroni post hoc analysis), but in case of rCBV, the mean perfusion values in each region approached to the normal level and it was difficult to differentiate between the two regions on the rCBV map. The rCBF in the regions 1, 2 and 3 was 0.40, 0.64, and 0.84, respectively. The difference of the threshold values of the rCBF between regions 2 and 3 was 0.75. There was no significant correlation between the time that elapsed after symptom onset and the perfusion values of each region on the rCBV, rCBF and MTT map. Conclusion: The perfusion values between the area of the initial infarction, the area that progressed to infarction and the hypoperfused but surviving area showed significant differences. The rCBF was the most useful parameter in differentiating between areas that progressed to infarction and the surviving areas. Quantitative measurement of the perfusion values may have a role in selecting the candidates for thrombolysis after they have suffered hyperacute stroke.

Cerebral bloodflow in and around spontaneous malignant gliomas.

Knowledge of the cerebral bloodflow (CBF) in and around malignant gliomas is of crucial importance in developing strategies for hyperthermia-, radiation-, and chemo-therapy of these difficult to cure lesions. To gather data regarding this important physiological variable, the perfusion distributions of 26 patients who had either a glioblastoma multiforme or an anaplastic astrocytoma were determined using stable xenon computed tomography (XeCT). Perfusion values were determined for each of the following anatomical regions: low density tumour core, the enhancing active ring of the tumour, the low density peripheral region of edema, an ipsilateral region of normal brain adjacent to the tumour, and a region of remote normal tissue on the contralateral side of the brain. A multiple regression analysis of the logs of the CBF values was used to analyse: (1) the differences in blood perfusion between the anatomical regions; and (2) the association of blood perfusion with various patient and tumour characteristics. Statistically significant differences in perfusion values were found between all of the anatomically outlined regions with the exceptions that the active tumour and edematous regions do not differ significantly from the ipsilateral normal brain tissue. The ipsilateral normal brain tissue adjacent to the tumour was found to have a relative perfusion (relative to the contra-lateral normal brain tissue perfusion) of 0.84, the edematous tissue had a relative perfusion of 0.52, the active tumour 0.78, and the core 0.39. Significant blood flow was present in the low density tumour core, contradicting the frequent assumption that there is zero or minimal blood flow in such regions. Multiple regression analysis was used to look for other variables that might be associated with blood flow after adjusting for the differences between anatomical regions. This analysis found a significant negative correlation between tumour blood-flow and tumour volume. It also estimated that blood flow in GMB tumours was approximately 67% of that in lower grade tumours. Variables that were found not to be significantly correlated with blood flow were: patient sex, multiple lobe involvement, hemisphere involved, treatment status (initial vs recurrent disease), Karnofsky performance status, age and, lobe involved.