Role of pulmonary perfusion magnetic resonance imaging for the diagnosis of pulmonary hypertension:A review

Among five types of pulmonary hypertension,chronic thromboembolic pulmonary hypertension(CTEPH)is the only curable form,but prompt and accurate diagnosis can be challenging.Computed tomography and nuclear medicine-based techniques are standard imaging modalities to non-invasively diagnose CTEPH,however these are limited by radiation exposure,subjective qualitative bias,and lack of cardiac functional assessment.This review aims to assess the methodology,diagnostic accuracy of pulmonary perfusion imaging in the current literature and discuss its advantages,limitations and future research scope.

Quantification of angiogenesis by CT perfusion imaging in liver tumor of rabbit

BACKGROUND:Tumor angiogenesis is essential for primary and metastatic tumor growth.Computed tomography perfusion(CTP)is a new imaging method,made possible by the recent development of fast CT scanners and improved data analysis techniques,which allows measurement of the physiologic and hemodynamic properties of tissue vasculature.This study aimed to evaluate CTP in the quantification of angiogenesis and to assess the relationship between tissue perfusion parameters and microvascular density(MVD)and vascular endothelial growth factor(VEGF),attempting to detect the physiologic properties of angiogenesis.METHODS:Sixteen rabbits with VX2 liver tumors underwent multi-slice CT perfusion(MSCTP)on day 14 after tumor inoculation.CTP parameters included hepatic blood flow(HBF),hepatic blood volume(HBV),mean transit time(MTT),permeability of capillary vessel surface(PS),hepatic artery index(HAI),hepatic artery perfusion(HAP),and hepatic portal perfusion(HPP).The border of the tumor was stained with CD34 and VEGF immunohistochemical stains,and MVD was measured by anti-CD34.Then,CTP parameters were determined whether they were correlated with MVD and VEGF using Pearson’s correlation coefficient.RESULTS:The positive expression of MVD was different in the center and border of the tumor(P【0.01).There was a positive correlation between MVD and VEGF in the border(P【0.05).As more VEGF was expressed,the number of microvessels increased.Correlation analyses were also made between the perfusion parameters and MVD and VEGF in the border of the tumor.HBF,PS,HAI,and HAP values were positively correlated with MVD and VEGF(P【0.05),HPP was negatively correlated with MVD and VEGF(P【0.01),and HBV and MTT values were not correlated with MVD and VEGF(P】0.05).CONCLUSIONS:Significant correlations were found between perfusion parameters and MVD and VEGF.Therefore,MSCTP can be used to evaluate tumor angiogenesis in vivo.

Assessment of tumor vascularization with functional computed tomography perfusion imaging in patients with cirrhotic liver disease

BACKGROUND:Hepatocellular carcinoma(HCC)is a common malignant tumor in China,and early diagnosis is critical for patient outcome.In patients with HCC,it is mostly based on liver cirrhosis,developing from benign regenerative nodules and dysplastic nodules to HCC lesions,and a better understanding of its vascular supply and the hemodynamic changes may lead to early tumor detection.Angiogenesis is essential for the growth of primary and metastatic tumors due to changes in vascular perfusion,blood volume and permeability.These hemodynamic and physiological properties can be measured serially using functional computed tomography perfusion(CTP)imaging and can be used to assess the growth of HCC.This study aimed to clarify the physiological characteristics of tumor angiogenesis in cirrhotic liver disease by this fast imaging method. METHODS:CTP was performed in 30 volunteers without liver disease(control subjects)and 49 patients with liver disease (experimental subjects:27 with HCC and 22 with cirrhosis). All subjects were also evaluated by physical examination, laboratory screening and Doppler ultrasonography of the liver. The diagnosis of HCC was made according to the EASL criteria. All patients underwent contrast-enhanced ultrasonography, pre-and post-contrast triple-phase CT and CTP study.A mathematical deconvolution model was applied to provide hepatic blood flow(HBF),hepatic blood volume(HBV), mean transit time(MTT),permeability of capillary vessel surface(PS),hepatic arterial index(HAI),hepatic arterial perfusion(HAP)and hepatic portal perfusion(HPP)data. The Mann-Whitney U test was used to determine differences in perfusion parameters between the background cirrhotic liver parenchyma and HCC and between the cirrhotic liver parenchyma with HCC and that without HCC.RESULTS:In normal liver,the HAP/HVP ratio was about 1/4. HCC had significantly higher HAP and HAI and lower HPP than background liver parenchyma adjacent to the HCC.The value of HBF at the tumor rim was significantly higher than that in the controls.HBF,HBV,HAI,HAP and HPP,but not MTT and PS,were significantly higher in the cirrhotic liver parenchyma involved with HCC than those of the controls. Perfusion parameters were not significantly different between the controls and the cirrhotic liver parenchyma not involved with HCC. CONCLUSIONS:CTP can clearly distinguish tumor from cirrhotic liver parenchyma and controls and can provide quantitative information about tumor-related angiogenesis, which can be used to assess tumor vascularization in cirrhotic liver disease.

Hepatic abnormal perfusion visible by magnetic resonance imaging in acute pancreatitis

AIM:to study the prevalence and patterns of hepatic abnormal perfusion(HAP)visible by magnetic resonance imaging(MRI)in acute pancreatitis(AP).METHODS:Enhanced abdominal MRI was performed on 51 patients with AP.these patients were divided into two groups according to the MRI results:those with signs of gallstones,cholecystitis,common bile duct(CBD)stones or dilatation of the CBD on MRI and those without.the prevalence,shape and distribution of HAP in the two groups were analyzed and compared.the severity of AP was graded using the MR severity index(MRSI).the correlation between the MRSI and HAP was then analyzed.RESULTS:Of the 51 patients with AP,32(63%)showed at least one sign of gallbladder and CBD abnormalities on the MR images,while 19(37%)showed no sign of gallbladder or CBD abnormalities.Nineteen patients(37%)had HAP visible in the enhanced images,including strip-,wedge-or patch-shaped HAP distributed in the hepatic tissue adjacent to the gallbladder and left and right liver lobes.there were no significant differences in the prevalence of HAP(χ2=0.305,P=0.581>0.05)or HAP distribution in the liver(χ2=2.181,P=0.536>0.05)between patients with and without gallbladder and CBD abnormalities.there were no significant differences in the MRSI score between patients with and without HAP(t=0.559,P=0.552>0.05).HAP was not correlated with the MRSI score.CONCLUSION:HAP is common in patients with AP and appears strip-,patch-or wedge-shaped on MRI.HAP on MRI cannot be used to indicate the severity of AP.

Experimental Study of Multi-slice Spiral CT Perfusion Imaging in VX_ 2 Soft-tissue Tumor of Rabbits

An experimental animal model of malignant soft-tissue tumor was established to investigate the applied value of multi-slice spiral CT perfusion imaging preliminarily. Ten New Zealand white rabbits which were implanted with VX2 tumor in either proximal thigh were subjected to CT plain scan and perfusion scan two weeks later respectively, then the original perfusion images were transmitted to AW4.0 Workstation. The functional maps and perfusion parameters including blood flow （BF）, blood volume （BV）, mean transit time （MTT） and permeability surface （PS） were computed and analyzed. All the values of BF, BV and PS in VX2 soft-tissue tumors were obviously higher while the MTT-values were lower than those in the normal muscular tissues significantly. It was suggested that multi-slice spiral CT perfusion imaging is an accurate, convenient and relatively safe functional imaging technique, and can give a quantitative assessment to angiogenesis and blood perfusion of soft-tissue tumors.

Cerebral perfusion in corresponding blood supply areas of transient ischemic attack patients with intracranial stenosis Seven cases of diamox-perfusion verified by magnetic resonance-perfusion-weighted imaging

BACKGROUND： Due to collateral circulation and cerebrovascular reserve, arterial stenosis and reduced cerebral blood flow may not necessarily indicate impaired cerebral peffusion. Therefore, according to degree of stenosis and clinical symptoms, interventional surgery to relieve arterial stenosis in transient ischemic attack （TIA） patients with major intracranial stenosis is imprudent. Rather, cerebral perfusion and reserve capacity are direct indicators for the assessment of degree and presence of cerebral ischemia. OBJECTIVE： To evaluate cerebral perfusion and reserve in TIA patients with major intracranial stenosis or occlusion using magnetic resonance-perfusion-weighted imaging （MR-PWl） data prior to and following diamox administration. DESIGN, TIME AND SETTING： A self-comparative, neuroimaging observation was performed at the Neurological Department and Radiological Center of the First Affiliated Hospital of Jinan University between December 2007 and April 2009. PARTICIPANTS： Seven acute TIA patients, who were admitted to the Neurological Department of the First Affiliated Hospital of Jinan University between December 2007 and April 2009, were enrolled in the present study. Magnetic resonance imaging confirmed that no acute cerebral infarction happened, nor did bleeding exist. Magnetic resonance angiography, transcranial Doppler ultrasound, and/or digital subtraction angiography confirmed the presence of major intracranial arterial stenosis. Clinical symptoms corresponded to blood supplying regions of the arterial stenosis. METHODS： Baseline MR-PWI was performed on seven patients with intracranial stenosis or occlusion. Two grams of acetazolamide （diamox） were orally administered after 2 days. A second PWl was performed after 2 hours to compare cerebral perfusion parameters prior to and following diamox administration. MAIN OUTCOME MEASURES： PWI results of cerebral perfusion prior to and following diamox administration. RESULTS： The baseline PWl from five patients indicated decreased cerebral perfusion areas. Following oral administration of diamox, cerebral perfusion significantly decreased in those areas. Moreover, new areas of decreased cerebral perfusion were observed in two out of the five patients. In one patient, no significant decrease in cerebral perfusion was found. In another patient, baseline PWl indicated decreased cerebral perfusion in the left hemisphere. However, normal perfusion was observed in both cerebral lobes following diamox administration. CONCLUSION： TIA patients with intracranial stenosis, who are diagnosed by PWI and exhibited decreased cerebral perfusion and reserve, might require further treatment such as intervention by angioptasty.

EVALUATION OF CIRRHOTIC LIVER WITH PERFUSION-WEIGHTED MAGNETIC RESONANCE IMAGING:A PRELIMINARY EXPERIMENTAL STUDY IN ANIMAL MODELS WITH HALF-LIVER CIRRHOSIS

Objective To investigate the role of peffusion-weighted magnetic resonance imaging （MRI） in evaluation of cirrhotic fiver. Methods With a 4F catheter, 1% diluted carbon tetrachloride （ 1 ml/kg） was selectively injected into fight or left hepatic artery of 12 dogs fortnightly. The half fiver into which carbon tetrachloride was injected was called as study side （SS）, while the other half fiver without carbon tetrachloride injection was called as study control side （SCS）. Conventional and peffusion-weighted MRI were performed in every 4 weeks. Via a 4F catheter, 5ml gadolinium diethylentriamine pentaaceti acid （Gd-DTPA） dilution was injected into superior mesenteric artery at the 5th scan. The signal intensity-thne curves of SS, SCS, and portal vein were completed in MR workstation. The maximal relative signal increase （ MRSI）, peak time （ tp）, and slope of the curves were measured. Results On conventional MR images, no abnormalities of externality and signal intensity were observed in both SS and SCS of fiver at each stage. The mean tp, MP, SI, and slope of intensity-time curves in normal fiver were 10. 56 seconds, 1.01, and 10. 23 arbitrary unit （au）/s, respectively. Three parameters of curves didn＇t show obvious change in SCS of fiver at every stage. Abnormal perfusion curves occurred in SS of fiver at the 12th week after the 1st injection. The abnormality of perfusion curve in SS was more and more serious as the times of injection increased. The mean tp, IVlRSI, and slope intensity-time curves in SS of fiver were 19.45 seconds, 0. 43, and 3. 60 au/s respectively at the 24th week. Conclusion Perfusion-weighted imaging can potentially provide information about portal peffusion of hepatic parenchyma, and to some degree, reflect the severity of cirrhosis.

Value of MR perfusion imaging after intervention treatment of hepatic cancer

Objective： To investigate the value of MR perfusion imaging in evaluating the curative effect of intervention treatment of hepatic cancer. Methods： 36 patients underwent MR perfusion imaging after intervention treatment. The quantization results were differed between carcinoma residue and benign tissue. And the diagnosis accuracy was judged, Results： There was a significant difference in mean MSI between residue tumor after surgery and the benign enhancement area. The timeintension curve of residue tumor was observed to ascend rapidly to reach the peak, whereas that of the enhancement tissue ascended slowly to reach the peak. The sensitivity and specificity of PWl on detection of residuary or recurrent tumor were 0.89 and 0.73 respectively. Conclusion： PWl is a very sensitive imaging technique that can be used to distinguish liver tissue condition after surgery. PWI contributed to early stage diagnosis and dynamic monitoring following HCC surgery.

Application of T2~*-weighted first-pass perfusion imaging in the diagnosis of breast tumors

Objective:To study the diagnostic value of T2*-weighted first-pass perfusion imaging in breast tumors.Methods: We analyzed the magnetic resonance imaging(MRI)information along with the pathological and immunohistochemistry re- sults.Magnetic resonance imaging was performed in 28 patients with breast tumor.The time to signal intensity curves were generated according to the T2*-weighted first-pass perfusion imaging.The curve’s maximal signal intensity drop rate and maximal signal intensity decrease time were analyzed and compared with the pathological diagnoses after surgery.Results: Malignant breast lesions showed higher maximal signal intensity drop rate(44.69%±17.07 vs.17.22%±7.49,P<0.001) than benign lesions,but there was no significant difference of maximal signal decrease time between those two lesions(23.94 s±4.92 vs.20.02 s±6.83,P>0.05).Conclusion:The T2*-weighted first-pass perfusion imaging has enough sensitivity and specificity in breast tumor diagnosis.

A Controlled Study on Comparing Differences in CT Perfusion Imaging between Rabbits inoculated with VX2 Lung Tumor and Patients with Squamous Cell Carcinoma of the Lung

OBJECTIVE By analysis and evaluation of the perfusion images and perfusion parameters of the rabbits with VX2 lung tumor, the association between the perfusion parameters and tumor angiogenesis of patients with squamous cell carcinoma of the lung has been studied in order to establish a non-invasive and effective way to detect tumor blood supply, which is be able to exhibit hemodynamic data in tumors during cancer treatments. METHODS Fifteen Netherlands rabbits inoculated with VX2 lung tumor （rabbit group） and 25 patients with squamous cell carcinoma of the lung （patient group） received a multi-slice spiral CT perfusion imaging test using the Netherlands PHILIPS Brilliance 16-slice spiral CT and a U.S. MEDRAD binocular highpressure syringe. Image postprocessing was done using the special perfusion software and EBW 4.0 Workstation. Perfusion volume （PV）, peak enhanced increment （PEI）, transit time peak （TTP）, and blood volume （BV） were measured and analyzed. RESULTS In the rabbit group, the values of the PV, PEI, TTP, and BV of the tumor margin were （53.89 ± 13.38） mL/（min.mL）, （45.71 ± 15.52） Hu, （39.29 ± 10.10） sec, and （31.45 ± 18.19） mL/100 g, respectively; these values of the tumor center were （36.57 ± 14.17） mL/（min.mL）, （28.64 ± 11.74） Hu, （39.00 ＋ 9.78） sec, and （19.76 ± 13.95） mL/100 g, respectively; the values of the muscles were （12.45± 4.38） mL/（min.mL）, （10.98 ± 5.03） Hu, （38.86 ± 10.04） sec, and （5.38 ±2.87） mL/100 g, respectively. The values of the relative perfusion volume （RPV）, relative peak enhanced increment （RPEI）, and relative blood volume （RBV） of the tumor margin were 4.38 ± 1.45, 3.96± 1.45, 9.99 ± 11.7, respectively; these values of the tumor center were 2.14 ± 1.08, 1.83±1.45, 4.17 ±3.39, respectively. The values of the PV, PEL BV of the tumor margin vs. the values of the muscles developed t-values, which were 15.028, 10.79, and 5.88, respectively （P ≤ 0.01）, with statistical significance; the values of the PV, PEI, BV of the tumor center vs. the values of the muscles produced t-values, which were 8.67, 7.49, and 4.55, respectively （P 〈 0.01）, with statistical significance. The values of the TTP of the tumor margin vs. TTP values of the muscles, and the TTP values of the tumor center vs. TTP values of the muscles developed t-values, which were 1.7 and 0.806, respectively （P ≥ 0.05）, without statistical significance. In the patient group, the values of the PV, PE, TTP, and BV of the tumor margin were （88.95 ± 30.89） mL/（min.mL）, （61.87 ± 27.31） Hu, （37.72 ± 12.53） sec, and （18.38 ± 7.2） mL/100 g, respectively; these values of the tumor center were （39.77 ± 18.29） mL/（min.mL）, （14.57 ± 8.1） Hu, （35.64 ± 12.41） sec, and （11.22 ± 6.02） mL/100 g, respectively; these values of the muscles were （12.45 ± 6.5） mL/（min.mL）, （6.14 ± 2.66） Hu, （35.68± 12.35） sec, and （2.23 ± 1.11） mL/100 g, respectively. The values of the RPV, RPEI, and RBV of the tumor margin were 8.05 ± 5.04, 8.87 ± 4.32, and 12.16 ± 8.49, respectively; these values of the tumor center were 2.39 ± 1.68, 2.97 ± 2.1, 3.53 ± 2.82, respectively. The values of the PV, PEI, BV of the tumor margin in the patient group vs. the values of the muscles produced t-values, which were 13.8, 10.85, and 12.22, respectively （P 〈 0.01）, with significant differences; these values of the tumor center vs. the values of the muscles developed t-values, which were 9.158, 6.26, 8.654, respectively （P 〈 0.01）, with significant differences. The TTP value of the tumor margin vs. that of the muscles produced t-value, which was 0.371, and the TTP value of the tumor center vs. that of the muscles developed t-value, which was 1 （P 〉 0.05）, without statistical difference. CONCLUSION CT perfusion imaging technics demonstrates directly dynamic changes of blood flow to tumors, which assists in identifying tumor growth and necrosis, therefore, this research provides an evidence-based guidelines for the treatment of human lung squamous cell carcinoma and has far-reaching clinical significance.

CT Perfusion Imaging Predicts One-Month Outcome in Patients with Acute Spontaneous Hypertensive Intracerebral Hemorrhage

Purpose: Little is known about the relationship between perihematomal perfusion parameters in acute spontaneous hypertensive intracerebral hemorrhage patients and recent outcome. The purpose of this study was to evaluate the relationship between the perfusion parameters of the perihematomal brain tissue and the recent prognosis of patients with acute spontaneous hypertensive intracerebral hemorrhage (shICH) using CT perfusion (CTP) imaging. Methods: Twenty-six patients with clinical and CT diagnosed supratentorial shICH received CTP scanning within 8 - 19 h after symptom onset. At the maximum levels of the hematoma, cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) of perihematomal area (isodense within 1cm rim of perilesion area on plain CT) and contralateral mirrored hemisphere were measured, and rCBF, rCBV, rMTT were calculated (ipsilateral/contralateral). The one-month follow-up in accordance with daily living table (Barthel index, BI) by telephone was recorded. Results: The CBV, CBF, and MTT values of perihematoma area were (1.61 ± 1.53) ml·100 g-1, (16.48 ± 12.58) ml·100 g-1·min-1, and (9.12 ± 2.57) s, respectively. (For more information,please refer to the PDF)

MR perfusion and diffusion imaging for the diagnosis of benign and malignant bone tumors

Objective： MR-PWI and MR-DWI were supplementary functional methods to differentiate benign from malignant bone tumors. The aim of this study was to assess the diagnostic potential of MR-PWI conjunction with MR-DWI in differentiating benign from malignant bone tumors. Methods： MR-PWI and MR-DWI were performed on 39 patients by using a 1.5 T MR imager. Perfusion imaging was started with GRE-EPI sequence as soon as the bolus administration commenced. With b value as 300 s/mm^2, diffusion imaging was performed with SE-EPI sequence. Type of TIC, peak enhancement, steepest slope, signal difference between 2 baselines and ADC were compared between benign and malignant bone tumors. The data were analyzed with soft-ware （SPSS, version 13.0）. Subjective overall performance of two techniques was evaluated with Receiver Operating Characteristic （ROC） analysis. Results： 1. MR-PWI： （1） The Patterns of TIC of most benign bone tumors （17/21） were type Ⅰ and Ⅱ, and all malignant bone tumors were type Ⅲ and Ⅳ. （2） There were significant differences in peak enhancement （17.52 ± 2.37 vs. 52.42 ± 5.74） %, steepest slope （4.69 ± 2.84 vs. 9.63 ± 4.05）%/s and signal difference between 2 baselines （6.87 ±3.34 vs. 31.75 ± 11.09） % between benign and malignant groups. And their diagnosis accuracy was 82.1%, 79.5% and 87.2%, respectively. （3）. 4 highly vascularized benign bone tumors were mistaken in diagnosis as malignant ones according to their perfusion characteristics. 2. MR-DWI： There was significant difference between ADC of benign and malignant groups [（1.86 ± 0.38） vs. （1.44± 0.26）] ×10^-3 mm^2/s when b value was 300 s/mm^2. The diagnosis accuracy was 79.5% when ADC value less than 1.63 × 10^-3 mm^2/s was considered as malignant ones. 3. The diagnosis accuracy of M R-PWI and MR-DWI were 89.7% and 79.5%, respectively. Conclusion： MR-PWI is the better valuable technique than MR-DWI in differentiation benign from malignant bone tumors. To suspicious highly vascularized bone tumors, MR-PWI combining with MR-DWI lead to higher diagnosis accuracy.

Three-dimensional arterial spin labeling and diffusion kurtosis imaging in evaluating perfusion and infarct area size in acute cerebral ischemia

BACKGROUND Early thrombolytic therapy is crucial to treat acute cerebral infarction,especially since the onset of thrombolytic therapy takes 1-6 h.Therefore,early diagnosis and evaluation of cerebral infarction is important.AIM To investigate the diagnostic value of magnetic resonance multi-delay threedimensional arterial spin labeling(3DASL)and diffusion kurtosis imaging(DKI)in evaluating the perfusion and infarct area size in patients with acute cerebral ischemia.METHODS Eighty-four patients who experienced acute cerebral ischemia from March 2019 to February 2021 were included.All patients in the acute stage underwent magnetic resonance-based examination,and the data were processed by the system’s own software.The apparent diffusion coefficient(ADC),average diffusion coefficient(MD),axial diffusion(AD),radial diffusion(RD),average kurtosis(MK),radial kurtosis(fairly RK),axial kurtosis(AK),and perfusion parameters post-labeling delays(PLD)in the focal area and its corresponding area were compared.The correlation between the lesion area of cerebral infarction under MK and MD and T2-weighted imaging(T2WI)was analyzed.RESULTS The DKI parameters of focal and control areas in the study subjects were compared.The ADC,MD,AD,and RD values in the lesion area were significantly lower than those in the control area.The MK,RK,and AK values in the lesion area were significantly higher than those in the control area.The MK/MD value in the infarct lesions was used to determine the matching situation.MK/MD<5 mm was considered matching and MK/MD≥5 mm was considered mismatching.PLD1.5s and PLD2.5s perfusion parameters in the central,peripheral,and control areas of the infarct lesions in MK/MD-matched and-unmatched patients were not significantly different.PLD1.5s and PLD2.5s perfusion parameter values in the central area of the infarct lesions in MK/MD-matched and-unmatched patients were significantly lower than those in peripheral and control areas.The MK and MD maps showed a lesion area of 20.08±5.74 cm^(2) and 22.09±5.58 cm^(2),respectively.T2WI showed a lesion area of 19.76±5.02 cm^(2).There were no significant differences in the cerebral infarction lesion areas measured using the three methods.MK,MD,and T2WI showed a good correlation.CONCLUSION DKI parameters showed significant difference between the focal and control areas in patients with acute ischemic cerebral infarction.3DASL can effectively determine the changes in perfusion levels in the lesion area.There was a high correlation between the area of the infarct lesions diagnosed by DKI and T2WI.

Magnetic Resonance Perfusion Imaging in the Diagnosis of High-Grade Glioma Progression and Treatment-Related Changes: A Systematic Review

In patients with high grade gliomas (HGGs), progression after treatment can be difficult to diagnose due to treatment-related effects, which overlap in appearance with tumour progression on conventional magnetic resonance imaging (MRI) sequences. Specialised imaging methods have been studied for this purpose, though most institutions currently use histopathology or clinicoradiological follow-up for diagnosis. This publication aims to review the evidence for perfusion MRI techniques. The databases of Pubmed, MEDLINE, EMBASE and Scopus were searched using combinations of the subject headings high grade glioma and MRI perfusion. 41 articles fulfilled the inclusion criteria. Dynamic Susceptibility Contrast (DSC) MRI was the most extensively studied, with several studies achieving high sensitivities and specificities. Other techniques exhibiting potential include Dynamic Contrast Enhanced (DCE) MRI, Arterial Spin Labelling (ASL). However, these techniques are not widely used or available for clinical practice. Composite measures combining results from multiple techniques tended to achieve higher accuracies. Some publications compared processing software used or looked at machine learning with relative success. An issue common to the literature is the lack of standardisation in the reference standard and acquisition/processing methods. Furthermore, many had small sample sizes, and further consideration needs to be given with regards to timing of imaging, and treatment regimens received in such studies.

Dynamic Contrast-Enhanced Perfusion MR Imaging Measurements of Endothelial Permeability: Differentiation between Atypical and Typical Meningiomas

BACKGROUND: AND PURPOSE: The measurement of relative cerebral blood volume (rCBV) and the volume transfer constant (K(trans)) by means of dynamic contrast-enhanced (DCE) perfusion MR imaging (pMRI) can be useful in characterizing brain tumors. The purpose of our study was to evaluate the utility of these measurements in differentiating typical meningiomas and atypical meningiomas. METHODS: Fifteen patients with pathologically confirmed typical meningiomas and seven with atypical meningiomas underwent conventional imaging and DCE pMRI before resection.rCBV measurements were calculated by using standard intravascular

Erythropoietin reduces apoptosis of brain tissue cells in rats after cerebral ischemia/reperfusion injury:a characteristic analysis using magnetic resonance imaging

Some in vitro experiments have shown that erythropoietin （EPO） increases resistance to apoptosis and facilitates neuronal survival follow- ing cerebral ischemia. However, results from in vivo studies are rarely reported. Perfusion-weighted imaging （PWI） and diffusion-weighted imaging （DWI） have been applied successfully to distinguish acute cerebral ischemic necrosis and penumbra in living animals; therefore, we hypothesized that PWI and DWI could be used to provide imaging evidence in vivo for the conclusion that EPO could reduce apoptosis in brain areas injured by cerebral ischemia/reperfusion. To validate this hypothesis, we established a rat model of focal cerebral ischemia/ reperfusion injury, and treated with intra-cerebroventricular injection of EPO （5,000 U/kg） 20 minutes before injury. Brain tissue in the ischemic injury zone was sampled using MRI-guided localization. The relative area of abnormal tissue, changes in PWI and DWI in the ischemic injury zone, and the number of apoptotic cells based on TdT-mediated dUTP-biotin nick end-labeling （TUNEL） were assessed. Our findings demonstrate that EPO reduces the relative area of abnormally high signal in PWI and DWI, increases cerebral blood volume, and decreases the number of apoptotic cells positive for TUNEL in the area injured by cerebral ischemia/reperfusion. The experiment pro- vides imaging evidence in vivo for EPO treating cerebral ischemia/reperfusion injury.

Revascularization and outcomes in Veterans with moderate to severe ischemia on myocardial perfusion imaging

Background： The prevalence of ischemia on nuclear myocardial perfusion imaging （MPI） has been decreasing. Recent research has questioned the benefit of invasive revascularization for patients with moderate to severe ischemia. We hypothesized that patients with moderate to severe ischemia could routinely undergo successful revascularization. Methods： We analyzed data from 544 patients who underwent an MPI at a single academic Veterans Affairs Medical Center. Patients with moderate to severe ischemia, defined as a summed difference score （SDS） 8 or greater, were compared to the rest of the cohort. Results： Of the total cohort （n=544）, 39 patients had MPI studies with resultant moderate to severe ischemia. Patients with ischemia were more likely to develop coronary artery disease （74.4% versus 38.8%, P〈0.0001） and have successful revascularization （38.5% versus 4.0%, P〈0.0001） during the following year. Revascularization was attempted in 31 patients with moderate to severe ischemia, though only 15（47%） of these attempts were successful, Ischemia was predictive of myocardial infarction （5.1% versus 0.8%, P=0.01） within I year. Conclusion： Moderate to severe ischemia is an uncommon finding in a contemporary nuclear laboratory. Among patients with ischemia, revascularization is typically attempted but is frequently unsuccessful. Trial registration： This trial does not appear on a registry as it is neither randomized nor prospective.

Magnetic resonance perfusion imaging evaluation in perfusion abnormalities of the cerebellum after supratentorial unilateral hyperacute cerebral infarction

Magnetic resonance imaging （MRI） data of 10 patients with hyperacute cerebral infarction （≤6 hours） were retrospectively analyzed.Six patients exhibited perfusion defects on negative enhancement integral maps,four patients exhibited perfusion differences in pseudo-color on mean time to enhance maps,and three patients exhibited perfusion differences in pseudo-color on time to minimum maps.Dynamic susceptibility contrast-enhanced perfusion weighted imaging revealed a significant increase in region negative enhancement integral in the affected hemisphere of patients with cerebral infarction.The results suggest that dynamic susceptibility contrast-enhanced perfusion weighted imaging can clearly detect perfusion abnormalities in the cerebellum after unilateral hyperacute cerebral infarction.

Myocardial perfusion imaging in patients with a recent, normal exercise test

AIM: To investigate the added value of myocardial perfusion scintigraphy imaging (MPI) in consecutive patients with suspected coronary artery disease (CAD) and a recent, normal exercise electrocardiography (ECG). METHODS: This study was a retrospective analysis of consecutive patients referred for MPI during a 2-year period from 2006-2007 at one clinic. All eligible patients were suspected of suffering from CAD, and had performed a satisfactory bicycle exercise test (i.e. , peak heart rate > 85% of the expected, age-predicted maximum) within 6 mo of referral, their exercise ECG was had no signs of ischemia, there was no exercise-limiting angina, and no cardiac events occurred between the exercise test and referral. The patients subsequently underwent a standard 2-d, stress-rest exercise MPI. Ischemia was defined based on visual scoring supported by quantitative segmental analysis (i.e. , sum of stress score > 3). The results of cardiac catheterizationwere analyzed, and clinical follow up was performed by review of electronic medical files. RESULTS: A total of 56 patients fulfilled the eligibility criteria. Most patients had a low or intermediate ATPⅢ pretest risk of CAD (6 patients had a high pre-test risk). The referral exercise test showed a mean Duke score of 5 (range: 2 to 11), which translated to a low postexercise risk in 66% and intermediate risk in 34%. A total of seven patients were reported with ischemia by MPI. Three of these patients had high ATPⅢ pre-test risk scores. Six of these seven patients underwent cardiac catheterization, which showed significant stenosis in one patient with a high pre-test risk of CAD, and indeterminate lesions in three patients (two of whom had high pre-test risk scores). With MPI as a gate keeper for catheterization, no significant, epicardial stenosis was observed in any of the 50 patients (0%, 95% confidence interval 0.0 to 7.1) with low to intermediate pre-test risk of CAD and a negative exercise test. No cardiac events occurred in any patients within a median follow up period of > 1200 d. CONCLUSION: The added diagnostic value of MPI in patients with low or intermediate risk of CAD and a recent, normal exercise test is marginal.

Contrast investigation of multi-slice spiral CT perfusion imaging and pathological findings in VX2 soft-tissue tumor of rabbits

Objective: To perform a contrast investigation of multi-slice spiral CT (MSCT) perfusion imaging and pathological findings in VX2 soft-tissue tumor of rabbits, and discuss the applicative value of multi-slice spiral CT perfusion imaging in soft-tissue tumors. Methods: 8 Newzealand white rabbits were implanted with 0.1 ml VX2 tumor tissue suspension in bilateral proximal thighs. 14 days and 21 days later, CT plain scan and perfusion scan were performed on these rabbits respectively, then the images were transmitted to AW4.0 workstation, the functional maps and perfusion parameters including blood flow (BF), blood volume (BV), mean transit time (MTT) and permeability surface (PS) were computed and analyzed. Subsequently, the rabbits were sacrificed, the tumors of which were taken out for pathological examination. The correlation between MSCT functional parametric images and pathological findings was analyzed. Results: All the values of BF, BV and PS of VX2 soft-tissue tumors were obviously higher while the MTT-values were lower than those of the normal muscular tissues significantly (P<0.001). Conclusion: Multi-slice spiral CT perfusion imaging is an accurate, convenient and relatively safe functional imaging technique, which can give a quantitative assessment to blood perfusion and angiogenesis of soft-tissue tumors.