“PERFUSION CT IN PREDICTING THE DEVELOPMENT OF PANCREATIC NECROSIS IN EARLY STAGE OF SEVERE ACUTE PANCREATITIS”

PURPOSE: To evaluate the role of perfusion CT (PCT) scan in predicting the development of pancreatic necrosis (PN) in early stage of severe acute pancreatitis (SAP). MATERIALS AND METHODS: A total of 20 adult patients with a clinical diagnosis of SAP presenting within 72 hours of onset of symptoms with a positive SIRS criteria were included in the study. All the patients underwent PCT on a 128 slice MDCT scannerusing 40 ml of non-ionic iodinated contrast followed by post processing using vendor provided CT perfusion software whereby perfusion parameters were calculated. Perfusion defect (PD) was dened as pancreatic BF and/or BV qualitatively less than hepatic BF and/or BV respectively on the color coded maps. A follow up CECT abdomen was done after 2 weeks as a 'gold standard' to assess whether PN developed in the corresponding region of PD. RESULTS: 8 out of 20 patients developed perfusion defect (PD) on the PCT, of which 6 patients developed PN on the follow up scan. Patients who did not show any PD on the PCT (12 out of 20) did not develop necrosis on the follow up CECT. The sensitivity, specicity, PPV, NPV and accuracy of PCT in predicting necrosis was 100%, 85.71%, 75%, 100% and 90% respectively. The cut off values of pancreatic BF and BV in predicting the development of PN were 34.87 ml/100ml/min and 11.70ml/100ml respectively based on the ROC curve. CONCLUSION: PCT is a useful technique that can predict development of PN in the early stage of SAP so that early aggressive management can be initiated.

Comparison of Spectral and Perfusion Computed Tomography Imaging in the Differential Diagnosis of Peripheral Lung Cancer and Focal Organizing Pneumonia

ObjectiveTo investigate the spectral and perfusion computed tomography (CT) findings of peripheral lung cancer (PLC) and focal organizing pneumonia (FOP) and to compare the accuracy of spectral and perfusion CT imaging in distinguishing PLC from FOP.Materials and MethodsPatients who were suspected of having lung tumor and underwent “one-stop” chest spectral and perfusion CT, with their diagnosis confirmed pathologically, were prospectively enrolled from September 2020 to March 2021. Patients who were suspected of having lung tumor and underwent “one-stop” chest spectral and perfusion CT, with their diagnosis confirmed pathologically, were prospectively enrolled from September 2020 to March 2021. A total of 57 and 35 patients with PLC and FOP were included, respectively. Spectral parameters (CT40keV, CT70keV, CT100keV, iodine concentration [IC], water concentration [WC], and effective atomic number [Zeff]) of the lesions in the arterial and venous phases were measured in both groups. The slope of the spectral curve (K70keV) was calculated. The perfusion parameters, including blood volume (BV), blood flow (BF), mean transit time (MTT), and permeability surface (PS), were measured simultaneously in both groups. The differences in the spectral and perfusion parameters between the groups were examined. Receiver operating characteristic (ROC) curves were generated to calculate and compare the area under the curve (AUC), sensitivity, specificity, and accuracy of both sets of parameters in both groups.ResultsThe patients’ demographic and clinical characteristics were similar in both groups (P > 0.05). In the arterial and venous phases, the values of spectral parameters (CT40keV, CT70keV, spectral curve K70keV, IC, and Zeff) were greater in the FOP group than in the PLC group (P < 0.05). In contrast, the values of the perfusion parameters (BV, BF, MTT, and PS) were smaller in the FOP group than in the PLC group (P < 0.05). The AUC of the combination of the spectral parameters was larger than that of the perfusion parameters. For the former imaging method, the AUC, sensitivity, and specificity were 0.89 (95% confidence interval [CI]: 0.82–0.96), 0.86, and 0.83, respectively. For the latter imaging method, the AUC, sensitivity, and specificity were 0.80 (95% CI: 0.70–0.90), 0.71, and 0.83, respectively. There was no significant difference in AUC between the two imaging methods (P > 0.05).ConclusionSpectral and perfusion CT both has the capability to differentiate PLC and FOP. However, compared to perfusion CT imaging, spectral CT imaging has higher diagnostic efficiency in distinguishing them.

Noninvasive Assessment of Foot Perfusion in a Rabbit Model of Atherosclerosis Using Dynamic Volume Perfusion CT with an Upslope Method

Objectives: To evaluate the feasibility of foot dynamic volume CT with the upslope method and to demonstrate macrovascular reactivity and microvascular perfusion during cuff-induced reactive hyperemia state in a rabbit model of atherosclerosis.Materials and Methods: 30 New Zealand male rabbits were divided into 2 groups: dietary hypercholesterolemia induced atherosclerosis (n=10) and normal diet control (n=20). To measure for macrovascular reactivity, perfusion parameters of the left posterior tibial artery was measured at baseline and at reactive hyperemia state. For the evaluation of microvascular perfusion, color-coded perfusion map of the plantar dermis was generated for perfusion CT scan by an in-house dedicated analysis software based on upslope method. Dermal perfusion values were measured and analyzed before and after cuff-induced reactive hyperemia.Results: Foot dynamic volume CT with the upslope method demonstrated significant impairment of both macrovascular reactivity and microvascular perfusion in atherosclerotic rabbits during cuff-induced reactive hyperemia (CRH) state. Arterial time-to-peak of cholesterol-fed rabbits failed to show acceleration while healthy rabbits showed significant decrease in time. Microvascular perfusion calculated by perfusion value (P<0.01) and perfusion ratio (P=.014) showed decreased microvascular perfusion in cholesterol fed rabbits compared to healthy rabbits during CRH state. Post-CT pathologic examination revealed decreased endothelial cell density in cholesterol-fed rabbits (P<0.001).Conclusions: Foot perfusion CT using upslope method provides perfusion parameters for large arteries and a perfusion map of the foot during cuff-induced reactive hyperemia in rabbit models of atherosclerosis. It may be a useful tool for the quantitative and functional evaluation of atherosclerotic peripheral arterial disease.

Hemispheric cerebral blood flow predicts outcome in acute small subcortical infarcts

The association between baseline perfusion measures and clinical outcomes in patients with acute small subcortical infarcts (SSIs) has not been studied in detail. Post-processed acute perfusion CT and follow-up diffusion-weighted imaging of 71 patients with SSIs were accurately co-registered. Relative perfusion values were calculated from the perfusion values of the infarct lesion divided by those of the mirrored contralateral area. The association between perfusion measures with clinical outcomes and the interaction with intravenous thrombolysis were studied. Additionally, the perfusion measures for patients having perfusion CT before and after thrombolysis were compared. Higher contralateral hemispheric cerebral blood flow (CBF) was the only independent predictor of an excellent clinical outcome (modified Rankin Scale of 0-1) at 3 months (OR = 1.3, 95% CI 1.1–1.4, P = 0.001) amongst all the perfusion parameters, and had a significant interaction with thrombolysis (P = 0.04). Patients who had perfusion CT after thrombolysis demonstrated a better perfusion profile (relative CBF ≥1) than those who had perfusion CT before thrombolysis (After:45.5%, Before:21.1%, P = 0.03). This study implies that for patients with SSIs, hemispheric CBF is a predictor of clinical outcome and has an influence on the effect of intravenous thrombolysis.

Value of Perfusion CT in the Prediction of Intracerebral Hemorrhage after Endovascular Treatment

Background. Intracerebral hemorrhage (ICH) is a serious complication of endovascular treatment (EVT) in stroke patients with large vessel occlusion (LVO) and associated with increased morbidity and mortality. Aims. Identification of radiological predictors is highly relevant. We investigated the predictive power of computed tomography perfusion (CTP) parameters concerning ICH in patients receiving EVT. Methods. 392 patients with anterior circulation LVO with multimodal CT imaging who underwent EVT were analyzed. CTP parameters were visually evaluated for modified ASPECTS regions and compared between patients without ICH, those with hemorrhagic infarction (HI), and those with parenchymal hematoma (PH) according to the ECASS criteria at follow-up imaging and broken down by ASPECTS regions. Results. 168 received intravenous thrombolysis (IV-rtPA), and 115 developed subsequent ICH (29.3%), of which 74 were classified as HI and 41 as PH. Patients with HI and PH had lower ASPECTS than patients without ICH and worse functional outcome after 90 days ( p < 0.05 ). In 102 of the 115 patients with ICH, the deep middle cerebral artery (MCA) territory was affected with differences between patients without ICH, those with HI, and those with PH regarding cerebral blood volume (CBV) and blood-brain barrier permeability measured as flow extraction product (FED) relative to the contralateral hemisphere ( p < 0.05 ). Patients with PH showed larger perfusion CT infarct core than patients without ICH ( p < 0.01 ). Conclusion. None of the examined CTP parameters was found to be a strong predictor of subsequent ICH. ASPECTS and initial CTP core volume were more reliable and may be useful and even so more practicable to assess the risk of subsequent ICH after EVT.