Computed Tomography Perfusion Examination Research Articles

Real-time model-based cerebral perfusion calculation for ischemic stroke

Background and ObjectivesClinical diagnosis of ischemic stroke commonly relies on examining cerebral perfusion changes by using computed tomography perfusion (CTP) techniques. However, the radiation dose in CTP is quite higher in comparison to computed tomography angiography (CTA), with associated costs and time. MethodsHence, this study established a lumped-parameter model (LPM) of brain tissue microcirculation (BTM) based on CTA, aiming to achieve real-time calculation of cerebral perfusion. After validation of calculated flow results with clinical data, the BTM-LPM model was used to examine the changes in cerebral perfusion following ischemic stroke, in which the effects of nine anatomical structures of the Circle of Willis (CoW) together with various distribution patterns of stenosis in the feeding arteries were considered. ResultsWhen compared the calculated flow results from BTM-LPM with the clinically measured data of literature, the mean squared error (MSE) value for the feeding arteries was 3.9 % and its total value for microcirculatory flow in each region was 0.1 %. Notably, the calculation time was 35.6 s. In the case of the CoW missing the left and right posterior communicating artery, a 60 % stenosis of the basilar artery is likely to cause ischemic damage to some temporal and occipital lobes of the right and left hemispheres. While in the case of the CoW missing the anterior communicating artery and the left posterior communicating artery, ischemic damage to the entire frontal lobe and parts of the temporal and parietal lobes of the left hemisphere was found when 80 % stenosis occurred in the left internal carotid artery. ConclusionsThe BTM-LPM proposed in this study could accurately calculate cerebral perfusion in real time and demonstrated the importance of CoW anatomy in different ischemic injuries to cerebral tissue. The calculated cerebral perfusion would be a reference value for early diagnosis and preoperative planning of different ischemic injuries to cerebral tissue, thereby the BTM-LPM holds great promising for replacing CTP examination.

Temporal Evolution of Perihematomal Blood-Brain Barrier Compromise and Edema Growth After Intracerebral Hemorrhage

PurposeThe aim of this study was to investigate the temporal evolution of perihematomal blood-brain barrier (BBB) compromise and edema growth and to determine the role of BBB compromise in edema growth.MethodsSpontaneous intracerebral hemorrhage patients who underwent computed tomography perfusion (CTP) were divided into five groups according to the time interval from symptom onset to CTP examination. Permeability-surface area product (PS) maps were generated using CTP source images. Ipsilateral and contralateral mean PS values were computed in the perihematomal and contralateral mirror regions. The relative PS (rPS) value was calculated as a ratio of ipsilateral to contralateral PS value. Hematoma and perihematomal edema volume were determined on non-contrast CT images.ResultsIn the total of 101 intracerebral hemorrhage patients, the ipsilateral mean PS value was significantly higher than that in contralateral region (z = −8.284, p < 0.001). The perihematomal BBB permeability showed a course of dynamic changes including an increase in the hyperacute and acute phases, a decrease in the early subacute phase and a second increase in the late subacute phase and chronic phase. Perihematomal edema increased gradually until the late subacute phase and then slightly increased. There was a relationship between rPS value and edema volume (β = 0.254, p = 0.006).ConclusionThe perihematomal BBB permeability is dynamic changes, and edema growth is gradually increased in patients following intracerebral hemorrhage. BBB compromise plays an essential role in edema growth. The quantitative assessment of BBB compromise may provide valuable information in therapeutic interventions of intracerebral hemorrhage patients.

Multiple Cerebrovascular Occlusion With Hypothyroidism: A Powerful Compensation

Cerebral vascular occlusion can often cause severe neurological deficits. This study aims to describe a case characterized by multiple large vessel occlusions with hypothyroidism and without clinical symptoms. The patient’s blood vessel condition, compensatory pathway and perfusion situation were understood through medical history inquiry, neurological physical examination, combined with blood lipid, blood glucose, electrocardiogram, transcranial Doppler (TCD), brain computed tomography (CT), cerebral angiography, cerebral perfusion imaging and other examinations. The main symptoms of the patient were dizziness and headache, with no symptoms of neurological function loss. Digital subtraction angiography (DSA) showed multiple large vessel occlusions in the head and neck: the initial part of the left internal carotid artery, the M1 segment of the left middle cerebral artery, the V2 segment of the right vertebral artery, and the V3 terminal segment of the left vertebral artery. According to CT perfusion (CTP) examination, the blood flow (BF) value of the left temporoparietal occipital lobe was lower than that of the contralateral side, the mean blood flow passage time value was increased, and the cerebral blood volume (BV) was slightly higher than that of the contralateral side. Cerebral vascular occlusion is affected by many factors, hypothyroidism can accelerate the process of atherosclerosis, and in severe cases multiple large vessel occlusions may occur. Powerful compensatory mechanisms can reduce the incidence of stroke. J Med Cases. 2019;10(6):158-163 doi: https://doi.org/10.14740/jmc3303

Multiple Cerebrovascular Occlusion With Hypothyroidism: A Powerful Compensation

Cerebral vascular occlusion can often cause severe neurological deficits. This study aims to describe a case characterized by multiple large vessel occlusions with hypothyroidism and without clinical symptoms. The patient’s blood vessel condition, compensatory pathway and perfusion situation were understood through medical history inquiry, neurological physical examination, combined with blood lipid, blood glucose, electrocardiogram, transcranial Doppler (TCD), brain computed tomography (CT), cerebral angiography, cerebral perfusion imaging and other examinations. The main symptoms of the patient were dizziness and headache, with no symptoms of neurological function loss. Digital subtraction angiography (DSA) showed multiple large vessel occlusions in the head and neck: the initial part of the left internal carotid artery, the M1 segment of the left middle cerebral artery, the V2 segment of the right vertebral artery, and the V3 terminal segment of the left vertebral artery. According to CT perfusion (CTP) examination, the blood flow (BF) value of the left temporoparietal occipital lobe was lower than that of the contralateral side, the mean blood flow passage time value was increased, and the cerebral blood volume (BV) was slightly higher than that of the contralateral side. Cerebral vascular occlusion is affected by many factors, hypothyroidism can accelerate the process of atherosclerosis, and in severe cases multiple large vessel occlusions may occur. Powerful compensatory mechanisms can reduce the incidence of stroke. J Med Cases. 2019;10(6):158-163 doi: https://doi.org/10.14740/jmc3303

Repetitive Computed Tomography Perfusion for Detection of Cerebral Vasospasm–Related Hypoperfusion in Aneurysmal Subarachnoid Hemorrhage

Delayed cerebral infarction after aneurysmal subarachnoid hemorrhage (aSAH) still remains the leading cause of disability in patients that survive the initial ictus. It has been shown that computed tomography perfusion (CTP) imaging can detect hypoperfused brain areas. The aim of this study was to evaluate if a single acute CTP examination at time of neurologic deterioration is sufficient or if an additional baseline CTP increases diagnostic accuracy. Retrospective analysis of acute and baseline (within 24 hours after aneurysm treatment) CTP examinations of patients with neurologic deterioration because of vasospasm-related hypoperfusion. Patients without clinical deterioration during the vasospasm period served as control subjects. The following CTP parameters were analyzed for predefined brain regions: time to drain (TTD), mean transit time, time to peak, cerebral blood flow, and volume. Thirty-three patients with and 23 without neurologic deterioration were included. Baseline CTP examination did not ameliorate diagnostic accuracy of the acute CTP examination in symptomatic patients. The same was true for interhemispheric comparison of perfusion parameters of the acute examination. The CTP parameter with the highest diagnostic yield was TTD of the symptomatic brain region (threshold value, 4.7 seconds; sensitivity, 97%; specificity, 96%). Acute CTP examination in case of suspected vasospasm-induced neurologic deterioration after aSAH has the highest diagnostic accuracy to detect misery perfusion. Additional baseline CTP is not needed. The most sensitive parameter to detect critically perfused brain areas is TTD.

Feasibility of dual-low scheme combined with iterative reconstruction technique in acute cerebral infarction volume CT whole brain perfusion imaging.

The feasibility of application of low-concentration contrast agent and low tube voltage combined with iterative reconstruction in whole brain computed tomography perfusion (CTP) imaging of patients with acute cerebral infarction was investigated. Fifty-nine patients who underwent whole brain CTP examination and diagnosed with acute cerebral infarction from September 2014 to March 2016 were selected. Patients were randomly divided into groups A and B. There were 28 cases in group A [tube voltage, 100 kV; contrast agent, iohexol (350 mg I/ml), reconstructed by filtered back projection] and 31 cases in group B [tube voltage, 80 kV; contrast agent, iodixanol (270 mg I/ml), reconstructed by algebraic reconstruction technique]. The artery CT value, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), dose length product, effective dose (ED) of radiation and brain iodine intake of both groups were measured and statistically analyzed. Two physicians carried out kappa (κ) analysis on the consistency of image quality evaluation. The difference in subjective image quality evaluation between the groups was tested by χ2. The differences in CT value, SNR, CNR, CTP and CT angiography subjective image quality evaluation between both groups were not statistically significant (P>0.05); the diagnosis rate of the acute infarcts between the two groups was not significantly different; while the ED and iodine intake in group B (dual low-dose group) were lower than group A. In conclusion, combination of low tube voltage and iterative reconstruction technique, and application of low-concentration contrast agent (270 mg I/ml) in whole brain CTP examination reduced ED and iodine intake without compromising image quality, thereby reducing the risk of contrast-induced nephropathy.

Acute CT perfusion changes in seizure patients presenting to the emergency department with stroke-like symptoms: correlation with clinical and electroencephalography findings

To determine acute computed tomography perfusion (CTP) changes in seizure patients presenting with stroke-like symptoms and to correlate those changes with clinical presentation and electroencephalography (EEG). The medical records of all patients who presented to the emergency department with acute stroke-like symptoms and underwent CTP (n=1085) over a 5.5-year period were reviewed. Patients were included who had primary seizure as the final diagnosis, and underwent CTP within 3 hours of symptom onset. A subset of patients had a follow-up EEG within 7 days. The perfusion changes and EEG findings were compared between different clinical presentations. Eighteen of 1085 patients (1.7%) who underwent CTP following an acute stroke-like presentation were included. The abnormality on CTP was usually focal, unilateral hyperperfusion - increased relative cerebral blood flow (rCBF) and volume (rCBV) (n=14/18), which most often affected the temporal lobe. Those patients who presented with a motor or speech deficit (n=12) had a higher temporal lobe rCBV, and rCBF, and lower relative mean transit time (rMTT) compared to those with non-focal neurological deficit at presentation. Early EEG was available in 13 patients; a sharp-spike epileptiform EEG discharge pattern (n=5) was associated with higher temporal lobe ipsilateral rCBF and rCBV, and lower rMTT on admission CTP examination. Seizure patients who present with a unilateral motor or speech deficit most commonly have contralateral hyperperfusion in the corresponding eloquent brain regions on the acute-stage CTP examination. In such patients, epileptiform discharges on the early follow-up EEG are associated with ipsilateral hyperperfusion on the admission CTP.

CT perfusion in the characterisation of renal lesions: an added value to multiphasic CT.

Objective. To prospectively evaluate if computed tomography perfusion (CTp) could be a useful tool in addition to multiphasic CT in renal lesion characterisation. Materials and Methods. Fifty-eight patients that were scheduled for surgical resection of a renal mass with a suspicion of renal cell carcinoma (RCC) were enrolled. Forty-one out of 58 patients underwent total or partial nephrectomy after CTp examination, and a pathological analysis was obtained for a total of 49 renal lesions. Perfusion parameters and attenuation values at multiphasic CT for both lesion and normal cortex were analysed. All the results were compared with the histological data obtained following surgery. Results. PS and MTT values were significantly lower in malignant lesions than in the normal cortex (P < 0.001 and P = 0.011, resp.); PS, MTT, and BF values were also statistically different between oncocytomas and malignant lesions. According to ROC analysis, the accuracy, sensitivity, and specificity to predict RCC were 95.92%, 100%, and 66.7%, respectively, for CTp whereas they were 89.80%, 93.35%, and 50%, respectively, for multiphasic CT. Conclusion. A significant difference between renal cortex and tumour CTp parameter values may suggest a malignant renal lesion. CTp could represent an added value to multiphasic CT in differentiating renal cells carcinoma from oncocytoma.

Combined PET/CT-perfusion in patients with head and neck cancers

Computed tomography perfusion (CTP) can provide information about angiogenesis and blood-flow characteristics in tumours. [18F]Fluoro-2-deoxy-D-glucose-positron emission tomography/computed tomography (FDG-PET/CT) is one of the major oncological imaging techniques which provides information about viability of the tumour cell and partly also about its aggressiveness. The aim of the study was to investigate the relationship between FDG and CTP data in patients with head and neck cancers. Forty-one patients with a clinically suspected head and neck cancer were prospectively included. All patients underwent a combined PET/CT with an integrated CTP examination in the area of the head and neck tumour. CTP data (BF, BV and MTT) and PET data (SUVmax, SUVmean, TLG, PETvol) were compared between tumours and (1) healthy contralateral tissue, (2) inflammatory lesions, (3) metastatic lymph nodes, and CTP data and PET data were correlated in tumours. Thirty-five patients had a head and neck cancer. All CTP data were statistically different between tumours, inflammatory lesions, healthy tissue and metastatic lymph nodes; PET/CT data were in part significantly different. CTP and PET parameters were not significantly correlated. CTP and PET parameters were not significantly correlated; thus, the additional CTP values provide additional insights into tumour behaviour and their glycolytic status.

Assessment of perihematomal hypoperfusion injury in subacute and chronic intracerebral hemorrhage by CT perfusion imaging

Objective: To study alterations of perihematomal cerebral perfusion associated to subacute and chronic intracerebral hemorrhage (ICH) by means of computed tomography perfusion (CTP) imaging.Methods: Non-enhanced CT scan and CTP examination were performed in 12 patients with subacute and chronic supratentorial ICH. The hematoma volume was measured, and the regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV), mean transit time (MTT) and time-to-peak (TTP) adjacent to hematoma were measured in 11 of 12 cases.Results: Eleven patients with mean age of 58·1 years were finally analysed. Mean time interval from symptom onset to initial CTP scanning was 18·4 days; mean hematoma volume was 26·8 ml. The gradient of hypoperfusion around the hematoma was revealed by rCBF maps in 11 cases, and by rCBV maps in ten cases. The areas of delayed TTP and MTT were showed in 11 and ten cases, respectively. The degree of reduction in rCBV correlated strongly with the hematoma volume (rinner=0·764, p=0·006;router=0·703, p=0·016). There was no correlation between the changes in rCBF, rCBV, MTT and TTP and the time interval from symptom onset to initial CTP examination.Conclusion: We have concluded that the gradient of hypoperfusion surrounding the hematoma may still exist during the subacute and chronic phases after ICH. The alterations in rCBV correlate with the hematoma volume. We believe that the reperfusion injury marked by increased rCBV contributes to the perilesional brain injury. The quantitative CT perfusion measurements can provide valuable information in individual management and prognostic evaluation of ICH.

Perfusion computed tomography evaluation of angiogenesis in liver cancer

To investigate the value of computed tomography (CT) perfusion imaging for assessment of angiogenesis in liver cancer. Twenty-one patients with histologically proven liver cancer underwent CT perfusion examination. We compared the following perfusion parameters in the tumour area versus the non-tumour area: total blood flow (TBF), hepatic arterial perfusion (HAP), hepatic portal perfusion (HPP) and hepatic arterial perfusion index (HAPI). Slices of postoperative specimen were stained with haematoxylin-eosin and anti-CD34 immunohistochemistry. The slices were evaluated with emphasis on the CD34-positive neovasculature in the tumour parenchyma. Tumour microvascular density (MVD) was calculated according to the Weidner method. Pearson correlation was used to detect correlations between tumour MVD and tumour perfusion parameters. TBF and HPP in the tumour area were lower than in the non-tumour area (P < 0.05). HAP and HAPI in the tumour area were higher than those of the non-tumour area (P < 0.05). TBF and HAP in the tumour area correlated with MVD in the tumour (P < 0.05), with correlation coefficients of 0.849 and 0.829, respectively. CT perfusion imaging can quantitatively assess the blood supply and its distribution in liver cancer. TBF or HAP may be a useful parameter in assessing angiogenesis of liver cancer.

Computed tomography perfusion in living donor liver transplantation: an initial study of normal hemodynamic changes in liver grafts

Hepatic hemodynamic changes in grafts after living donor liver transplantation (LDLT) are complicated. In this study, computed tomography (CT) perfusion parameter values, especially portal vein perfusion (PVP), was retrospectively analyzed in recipients both with and without small-for-size syndrome (SFSS). PVP was significantly higher in non-SFSS recipients on post-operative day (POD) 14 or 28 than in normal donors before donation (p < 0.001 and p = 0.008, respectively), but it significantly decreased between 14 and 28 days post-operatively (p = 0.007). There was a significant inverse correlation between graft-to-recipient spleen size ratio and PVP on POD 14 in non-SFSS group (r = -0.545, p = 0.002). Furthermore, PVP in the SFSS group was significantly greater than in the non-SFSS group on POD 14 (p = 0.042). In conclusion, we successfully evaluated normal hemodynamic changes in grafts without SFSS by CT perfusion examination. To our knowledge, this is the first study on hemodynamic changes of living donor liver grafts using CT technique.