Perfusion computerized tomography can predict pancreatic necrosis in early stages of severe acute pancreatitis

Perfusion Computed Tomography for Assessing Pancreas Graft Volumetric Perfusion After Simultaneous Pancreas and Kidney Transplantation

Background: There is paucity of data in the available medical literature regarding the parameters of the volumetric perfusion of pancreas grafts. Methods: From 5 February 2016 to 23 December 2021, we performed perfusion computed tomography in 41 patients at different times after simultaneous pancreas and kidney transplantation. The study group consisted of 18 men (44%) and 23 women (56%) with a long history of type 1 diabetes mellitus complicated by terminal chronic renal failure. The results of the perfusion computed tomography of the pancreas graft were studied, and the effects of post-transplantation timing and graft revascularization peculiarities on volumetric perfusion parameters were evaluated. Results: The median arterial blood flow, arterial blood volume, and permeability of the pancreas graft were 115.1 [99.7;130.3] mL/100 mL/min, 46.7 [37.4;56.9] mL/min, and 8.6 [4.1;11.4] mL/100 mL/min, respectively. No statistically significant differences in the averaged perfusion values were found in the head, body, and tail of the pancreas graft. The post-transplantation timing and the number of arteries involved in graft revascularization did not have a significant effect on the volumetric perfusion of the graft. Conclusion: The volumetric perfusion results of the pancreas graft correspond to those obtained in the study of pancreatic perfusion in healthy participants.

The Role of CT Perfusion in Differentiating Benign Versus Malignant Focal Pulmonary Lesions

BACKGROUND

Contrast-enhanced CT scan is the standard imaging for the characterization and evaluation of focal parenchymal lung lesions. It relies on morphology and enhancement patterns for the characterization of lung lesions. However, there is significant overlap among imaging features of various malignant and benign lesions. Hence, it is often necessary to obtain tissue diagnosis with invasive percutaneous or endoscopic-guided tissue sampling. It is often desirable to have non-invasive techniques that can differentiate malignant and benign lung lesions. CT perfusion is an emerging CT technology that allows functional assessment of tissue vascularity through various parameters and can help in differentiating benign and malignant focal lung lesions.

OBJECTIVE

The purpose of this study was to assess the role of the CT perfusion technique in differentiating malignant and benign focal parenchymal lung lesions.

MATERIALS AND METHODS

In this prospective observational study, CT perfusion was performed on 41 patients with focal parenchymal lung lesions from December 2020 to June 2022. The four-dimensional range was planned to cover the entire craniocaudal extent of the lesion, followed by a volume perfusion CT (VPCT) of the lesion. A total of 27 dynamic datasets were acquired with a scan interval of 1.5 seconds and a total scan time of 42 seconds. CT perfusion parameters of blood flow (BF), blood volume (BV), and k-trans of the lesion were measured with mathematical algorithms available in the Syngo.via CT perfusion software (Siemens Healthcare, Erlangen, Germany).

RESULTS

The median BV in benign lesions was found to be 5.5 mL/100 g, with an interquartile range of 3.3-6.9 and a p-value < 0.001. The median BV in malignant lesions was found to be 11.35 mL/100 g, with an interquartile range of 9.57-13.21 and a p-value ≤ 0.001. The median BF for benign lesions was 45.5 mL/100 g/min, with an interquartile range of 33.8-48.5 and a p-value ≤ 0.001. The median BF for malignant lesion was 61.77 mL/100 g/min, with an interquartile range of 33.8-48.5 and a p-value ≤ 0.001. The median k-trans in the case of benign lesions was found to be 4.2 mL/100 g/min, with an interquartile range of 3.13-6.8 and a p-value ≤ 0.001. The median k-trans in the case of the malignant lesion was found to be 12.05 mL/100g/min, with an interquartile range of 7.20-33.42 and a p-value < 0.001. Our study has also shown BV to have an accuracy of 92.68%, sensitivity of 93.3%, and specificity of 90.01%.

CONCLUSION

Our study has shown that CT perfusion values of BV, BF, and k-trans can be used to differentiate between benign and malignant focal lung parenchymal lesions. K-trans is the most sensitive parameter while BV and BF have greater accuracy and specificity.

A Comprehensive Study on the Diagnostic Value of Multi-Slice Computed Tomography for Peripancreatic Infection in Elderly With Severe Acute Pancreatitis

BACKGROUND

This study investigated the diagnostic efficacy of multi-slice spiral computed tomography (MSCT) perfusion imaging in evaluating peripancreatic infection in elderly patients with severe acute pancreatitis (SAP).

METHODS

A retrospective analysis was conducted on the clinical data of 110 elderly SAP patients treated at our hospital from March 2018 to August 2019. The study correlated MSCT perfusion imaging characteristics with peripancreatic infection in elderly SAP patients. Additionally, receiver operating characteristic (ROC) curves were constructed to assess the diagnostic performance of MSCT perfusion imaging parameters in evaluating peripancreatic infection in elderly SAP patients.

RESULTS

The results indicated that among all 110 elderly SAP patients, the incidence rate of peripancreatic infection was 20.91%, with a mortality rate of 0.91%. MSCT perfusion imaging revealed that after peripancreatic infection in elderly SAP patients, there was a decrease in pancreatic density, local enlargement of the pancreas, blurring of the pancreatic margins, and associated ascites. Compression/narrowing/occlusion of the splenic vein was observed in 22 patients, compression/narrowing/occlusion of the superior mesenteric vein in 17 patients, thickening/thrombosis of the portal vein in 19 patients, and collateral circulation in 21 patients. Compared to elderly SAP patients without peripancreatic infection, those with the infection showed prolonged peak times, reduced peak heights, and decreased blood flow. ROC analysis indicated that the combination of the three parameters (peak time, peak height, and blood flow) had higher specificity and area under the curve (AUC) than single parameters, with no significant difference in sensitivity between the combination and single parameters.

CONCLUSIONS

In conclusion, combining the three key MSCT perfusion imaging parameters (peak time, peak height, and blood flow) can significantly enhance the predictive efficacy for the risk of peripancreatic infection in elderly SAP patients.

Computed tomographic evaluation of pancreatic perfusion in 10 dogs with acute pancreatitis

Severe canine acute pancreatitis can be fatal; imaging features that can predict the clinical course of disease are useful for clinicians. On computed tomography (CT), both pancreatic heterogeneous contrast enhancement and portal vein thrombosis have been correlated with poorer outcome. Perfusion CT is used in human medicine to evaluate pancreatic microcirculation to predict the future development of severe sequela to pancreatitis; this technology has yet to be explored in dogs with acute pancreatitis. The objective of this prospective, case-control study is to evaluate pancreatic perfusion using contrast-enhanced CT in dogs with acute pancreatitis and compare it with previously established values obtained in healthy dogs. Ten client-owned dogs preliminarily diagnosed with acute pancreatitis received a full abdominal ultrasound, specific canine pancreatic lipase (Spec cPL), and perfusion CT. Computer software calculated pancreatic perfusion, peak enhancement index, time to peak enhancement, and blood volume for 3-mm and reformatted 6-mm slices. The data was analyzed using Shapiro-Wilk test, linear mixed model, and Spearman's rho. Values for 3-mm slices were similar to 6-mm slices (all P < 0.05). Dogs with acute pancreatitis had a faster time to peak enhancement than healthy dogs (P = 0.04-0.06). Dogs with acute pancreatitis and homogeneous pancreatic enhancement had higher perfusion, faster time to peak enhancement, and greater blood volume compared to healthy dogs and dogs with acute pancreatitis and heterogeneous pancreatic enhancement (all P = / < 0.05). Pancreatic perfusion decreased with increased pancreatitis severity. No correlation was identified between Spec cPL and pancreatic perfusion (all P > 0.05). These findings preliminarily support perfusion CT in dogs with acute pancreatitis.

Pancreatic CT perfusion: quantitative meta-analysis of disease discrimination, protocol development, and effect of CT parameters

BACKGROUND

This study provides a quantitative meta-analysis of pancreatic CT perfusion studies, investigating choice of study parameters, ability for quantitative discrimination of pancreatic diseases, and influence of acquisition and reconstruction parameters on reported results.

METHODS

Based on a PubMed search with key terms 'pancreas' or 'pancreatic,' 'dynamic' or 'perfusion,' and 'computed tomography' or 'CT,' 491 articles published between 1982 and 2020 were screened for inclusion in the study. Inclusion criteria were: reported original data, human subjects, five or more datasets, measurements of pancreas or pancreatic pathologies, and reported quantitative perfusion parameters. Study parameters and reported quantitative measurements were extracted, and heterogeneity of study parameters and trends over time are analyzed. Pooled data were tested with weighted ANOVA and ANCOVA models for differences in perfusion results between normal pancreas, pancreatitis, PDAC (pancreatic ductal adenocarcinoma), and non-PDAC (e.g., neuroendocrine tumors, insulinomas) and based on study parameters.

RESULTS

Reported acquisition parameters were heterogeneous, except for contrast agent amount and injection rate. Tube potential and slice thickness decreased, whereas tube current time product and scan coverage increased over time. Blood flow and blood volume showed significant differences between pathologies (both p < 0.001), unlike permeability (p = 0.11). Study parameters showed a significant effect on reported quantitative measurements (p < 0.05).

CONCLUSIONS

Significant differences in perfusion measurements between pathologies could be shown for pooled data despite observed heterogeneity in study parameters. Statistical analysis indicates most influential parameters for future optimization and standardization of acquisition protocols.

CRITICAL RELEVANCE STATEMENT

Quantitative CT perfusion enables differentiation of pancreatic pathologies despite the heterogeneity of study parameters in current clinical practice.

Efficacy of Contrast-Enhanced Endoscopic Ultrasonography for the Diagnosis of Pancreatic Tumors

Endoscopic ultrasound can be useful for obtaining detailed diagnostic images for pancreatic disease. Contrast-enhanced harmonic endoscopic ultrasound has allowed to demonstrate not only microvasculature but also real perfusion imaging using second-generation contrast agents. Furthermore, endoscopic ultrasound fine-needle aspiration cytology and histology have become more ubiquitous; however, the risk of dissemination caused by paracentesis has yet to be resolved, and the application of less invasive contrast-enhanced endoscopic ultrasound for the differential diagnosis of pancreatic tumors has been anticipated. Contrast-enhanced harmonic endoscopic ultrasound can contribute to the differential diagnosis of pancreatic tumors.

Comparative analysis of two mathematical algorithms for the calculation of computed tomography perfusion parameters in the healthy and diseased pancreas

BACKGROUND

The maximum slope (MS) and deconvolution (DC) algorithms are commonly used to post-process computed tomography perfusion (CTP) data. This study aims to analyze the differences between MS and DC algorithms for the calculation of pancreatic CTP parameters.

METHODS

The pancreatic CTP data of 57 patients were analyzed using MS and DC algorithms. Two blinded radiologists calculated pancreatic blood volume (BV) and blood flow (BF). Interobserver correlation coefficients were used to evaluate the consistency between two radiologists. Paired t-tests, Pearson linear correlation analysis, and Bland-Altman analysis were performed to evaluate the correlation and consistency of the CTP parameters between the two algorithms.

RESULTS

Among the 30 subjects with normal pancreas, the BV values in the three pancreatic regions were higher in the case of the MS algorithm than in the case of the DC algorithm (t = 39.35, p < 0.001), and the BF values in the three pancreatic regions were slightly higher for the MS algorithm than for the DC algorithm (t = 2.19, p = 0.031). Similarly, among the 27 patients with acute pancreatitis, the BV values obtained using the MS methods were higher than those obtained using the DC methods (t = 54.14, p < 0.001). Furthermore, the BF values were higher with the MS methods than the DC methods (t = 8.45, p < 0.001). Besides, Pearson linear correlation and Bland-Altman analysis showed that the BF and BV values showed a good correlation and a bad consistency between the two algorithms.

CONCLUSIONS

The BF and BV values measured using MS and DC algorithms had a good correlation but were not consistent.

The value of a dual-energy spectral CT quantitative analysis technique in acute pancreatitis

AIM

To explore the value of dual-energy spectral computed tomography (DESCT) in evaluating the clinical severity of acute pancreatitis.

MATERIALS AND METHODS

Seventy patients with acute pancreatitis (AP) confirmed by clinical examination were included in this study. All patients underwent unenhanced/double-phase enhanced CT in spectral imaging mode. Iodine concentration and normalised iodine concentration (NIC) were measured retrospectively with a spectral imaging viewer (GSI Viewer). All data were analysed by analysis of variance. Receiver operating characteristic (ROC) curves were constructed to determine the optimal threshold for predicting the clinical severity of AP.

RESULTS

Seventy patients were included in the study comprising 30 mild, 22 moderate, and 18 severe cases of AP. The CT attenuation value, iodine concentration, and NIC were decreased with increasing clinical severity. Moreover, there were significant differences between the mild group and the severe group (p<0.05), as well as between the moderate group and the severe group (p<0.05). The area under the ROC curve AUC of each value was larger in arterial phase than in portal venous phase. The most sensitive value between the mild and severe groups in AP was the NIC (arterial phase: 0.19 ± 0.06; portal venous phase: 0.45 ± 0.09).

CONCLUSION

DESCT can provide multiple parameters to determine the severity of AP.

Effect of slice thickness on computed tomographic perfusion analysis of the pancreas in healthy dogs

OBJECTIVE

To evaluate the effect of slice thickness on CT perfusion analysis of the pancreas in healthy dogs.

ANIMALS

12 healthy Beagles.

PROCEDURES

After precontrast CT scans, CT perfusion scans of the pancreatic body were performed every second for 30 seconds by sequential CT scanning after injection of contrast medium (iohexol; 300 mg of 1/kg) at a rate of 3 mL/s. Each dog underwent CT perfusion scans twice in a crossover-design study with 2 different slice thicknesses (2.4 and 4.8 mm). Computed tomographic pancreatic perfusion variables, including blood flow, blood volume determined with the maximum slope model, times to the start of enhancement and peak enhancement, permeability, and blood volume determined by Patlak plot analysis, were measured independently by 2 reviewers. The CT perfusion variables were compared between slice thicknesses. Interoperator reproducibility was determined by ICC calculation.

RESULTS

Interoperator reproducibility of CT perfusion variable measurements was excellent on 2.4-mm (mean ± SD ICC, 0.81 ± 0.17) and 4.8-mm (0.90 ± 0.07) slice thicknesses, except for time to peak pancreatic enhancement on 2.4-mm-thick slices, which had moderate reproducibility (intraclass correlation coefficient, 0.473). There was no significant difference in measurements of blood flow, blood volume by either method, times to the start and peak of pancreatic enhancement, or permeability between slice thicknesses.

CONCLUSIONS AND CLINICAL RELEVANCE

Results supported that a thin slice thickness of 2.4 mm can be used for assessment of pancreatic perfusion variables in healthy dogs.

Pancreatic perfusion imaging method that reduces radiation dose and maintains image quality by combining volumetric perfusion CT with multiphasic contrast enhanced-CT

OBJECTIVES

The aim of this study is to propose and evaluate a new method of volumetric perfusion computed tomography (PCT) incorporated into pancreatic multiphasic contrast enhanced (CE)-CT in the clinical setting.

METHODS

In this ethically approved study, PCT was incorporated into our existing scanning protocol in 17 patients and effective doses related to PCT were evaluated. CT values and signal-to-noise ratio (SNR) of anatomical structure were compared in diagnostic images that were acquired using 320-detector volumetric scan mode and 64-detector helical scan mode. In addition, focal lesion depiction was qualitatively assessed in the two groups. Perfusion parameters in normal pancreas were measured by two radiologists and the interobserver-reliability was assessed.

RESULTS

The effective dose of PCT was 5.1 ± 0.3 mSv. The actual effective dose (AED) including the dose used in volumetric scans for diagnostic imaging was 22.8 ± 5.3 mSv and the putative effective dose (PED) was 21.9 ± 9.1 mSv on average. There was no significant difference between AED and PED (p = 0.404). Compared with conventional helical scans, volumetric scans did not decrease CT values or SNR, but rather significantly increased those of the aorta in the arterial phase. Both groups had acceptable qualitatively assessed image quality with no significant difference in the depiction of each structure. There was almost perfect interobserver agreement in the measurement of perfusion parameters (mean ICCs > 0.9).

CONCLUSIONS

Our scanning protocol for pancreatic perfusion CT provides high-quality images while requiring lower radiation doses than conventional methods.

Continuous regional arterial infusion versus intravenous administration of the protease inhibitor nafamostat mesilate for predicted severe acute pancreatitis: a multicenter, randomized, open-label, phase 2 trial

BACKGROUND

Continuous regional arterial infusion (CRAI) of protease inhibitor nafamostat mesilate (NM) is used in the context of predicted severe acute pancreatitis (SAP) to prevent the development of pancreatic necrosis. Although this therapy is well known in Japan, its efficacy and safety remain unclear.

METHODS

This investigator-initiated and -driven, multicenter, open-label, randomized, controlled trial (UMIN000020868) enrolled 39 patients with predicted SAP and low enhancement of the pancreatic parenchyma on computed tomography (CT). Twenty patients were assigned to the CRAI group, while 19 served as controls and were administered NM at the same dose intravenously (IV group). The primary endpoint was the development of pancreatic necrosis as determined by CT on Day 14, judged by blinded central review.

RESULTS

There was no difference between the CRAI and IV groups regarding the percentages of participants who developed pancreatic necrosis (more than 1/3 of the pancreas: 25.0%, range 8.7-49.1% vs. 15.8%, range 3.4-39.6%, respectively, P = 0.694; more than 2/3 of the pancreas: 20%, range 5.7-43.7% vs. 5.3%, range 0.1-26.0%, respectively, P = 0.341). The early analgesic effect was evaluated based on 24-h cumulative fentanyl consumption and additional administration by intravenous patient-controlled analgesia. The results showed that the CRAI group used significantly less analgesic. There were two adverse events related to CRAI, namely bleeding and splenic infarction.

CONCLUSIONS

CRAI with NM did not inhibit the development of pancreatic necrosis although early analgesic effect of CRAI was superior to that of IV. Less-invasive IV therapy can be considered a viable alternative to CRAI therapy.

Can Disturbed Liver Perfusion Revealed in p-CT on the First Day of Acute Pancreatitis Provide Information about the Expected Severity of the Disease?

Background

The aim of the study was to evaluate the prognostic properties of perfusion parameters of liver parenchyma based on computed tomography (CT) of patients with acute pancreatitis (AP) made on the first day of onset of symptoms, to assess their usefulness in identifying patients with increased risk of the development of severe AP.

Methods

79 patients with clinical symptoms and biochemical criteria indicative of AP underwent perfusion computed tomography (p-CT) within 24 hours after onset of the symptoms. Perfusion parameters in 41 people who developed a severe form of AP were compared with parameters in 38 patients in whom the course of AP was mild.

Results

Statistical differences in the liver perfusion parameters between the group of patients with mild and severe AP were shown. The permeability-surface area product was significantly lower, and the hepatic arterial fraction was significantly higher in the group of patients with progression of AP.

Conclusions

Based on the results, it seems that p-CT performed on the first day from the onset of AP is a method that, by revealing disturbances in hepatic perfusion, can help in identifying patients with increased risk of the development of severe AP.

Predictive factors for the mortality of acute pancreatitis on admission

Background and aims

The revised Atlanta classification is widely used for the evaluation of acute pancreatitis (AP) severity. However, this classification cannot be used within 48 hours of AP onset. The aim of this study was to investigate the predictive factors of mortality in patients with AP on admission.

Methods

We evaluated the association between AP mortality and clinical parameters at the time of admission in patients with AP from April 2013 to December 2017 at one university hospital and one tertiary care referral center.

Results

A total of 203 consecutive patients were enrolled. Nine patients (4.4%) died despite multidisciplinary treatment. In a multivariable analysis, hematocrit ≥ 40% (odds ratio [OR], 1.07; 95% confidence interval [CI], 1.01–1.13; P = 0.021), blood urea nitrogen (BUN) ≥ 40 mg/dL (OR, 1.26; 95% CI, 1.11–1.42; P < 0.001), base excess < -3.0 mmol/L (OR, 1.15; 95% CI, 1.04–1.26; P = 0.004), and inflammation extending to the rectovesical excavation (OR, 1.19; 95% CI, 1.10–1.30; P < 0.001) on admission were significantly associated with mortality.

Conclusion

Among the imaging findings, inflammation extending to the rectovesical excavation was the only independent predictive factor for mortality in AP. This simple finding, obtained on computed tomography without contrast agent on admission, might be a promising prognostic factor for AP.

Weight-adapted ultra-low-dose pancreatic perfusion CT: radiation dose, image quality, and perfusion parameters

PURPOSE

We evaluate the reliability and feasibility of weight-adapted ultra-low-dose pancreatic perfusion CT.

METHODS

A total of 100 (47 men, 53 women) patients were enrolled prospectively and were assigned to five groups (A, B, C, D, and E) with different combination of tube voltage and tube current according to their body weight. Radiation dose parameters including volume CT dose index (CTDI) and dose-length product (DLP) were recorded. Image quality was evaluated both subjectively and objectively (noise, signal-to-noise ratio, contrast-to-noise ratio). Perfusion parameters including blood flow (BF), blood volume (BV), and permeability (PMB) were measured. The dose, image quality measurements, and perfusion parameters were compared between the five groups using one-way analysis of variance (ANOVA).

RESULTS

Radiation dose reached 8.7 mSv in patients under 50 kg and was 18.9 mSv in patients above 80 kg. The mean subjective image quality score was above 4.45 on a 5-point scale with good agreement between two radiologists. Groups A-D had equivalent performance on objective image quality (P > 0.05), while Group E performed even better (P < 0.05). No significant differences emerged in comparison with perfusion parameters (BF, BV, PMB) of normal pancreas parenchyma between the five groups.

CONCLUSION

Weight-adapted ultra-low-dose pancreatic perfusion CT can effectively reduce radiation dose without prejudice to image quality, and the perfusion parameters of normal parenchyma are accurate and reliable.

The Accuracy of Pancreatic Perfusion Computed Tomography and Angiography in Predicting Necrotizing Pancreatitis: A Systematic Review

Early prediction of necrotizing pancreatitis is important for tailoring treatment, but current scoring systems have moderate accuracy and can be calculated only 24 to 48 hours after disease onset. Evaluation of (micro)circulatory changes in acute pancreatitis at admission by perfusion computed tomography (PCT) or angiography could predict necrosis earlier. Our aim was to systematically review the evidence for angiographic and PCT prediction of necrotizing pancreatitis. We performed a systematic review and searched MEDLINE and Embase. We included cohort studies addressing pancreatic perfusion for prognostication of severity of acute pancreatitis and assessed study quality with a tool specific for diagnostic accuracy studies. Six prospective cohorts with 334 patients were included. Sensitivity of PCT for predicting necrosis ranged from 71% to 100% and specificity from 74% to 100%. The only study directly comparing PCT and angiography found a similar sensitivity (100%) but higher specificity for PCT (90% vs 72%). The included studies had moderate quality. Current studies consistently demonstrate excellent sensitivity and specificity of PCT for early prediction of necrosis. The performance found in our review should be confirmed in larger prospective cohorts as published studies have moderate quality. Furthermore, it should be investigated whether early PCT improves disease course.

Advances in Pancreatic CT Imaging

OBJECTIVE

The purpose of this article is to discuss the advances in CT acquisition and image postprocessing as they apply to imaging the pancreas and to conceptualize the role of radiogenomics and machine learning in pancreatic imaging.

CONCLUSION

CT is the preferred imaging modality for assessment of pancreatic diseases. Recent advances in CT (dual-energy CT, CT perfusion, CT volumetry, and radiogenomics) and emerging computational algorithms (machine learning) have the potential to further increase the value of CT in pancreatic imaging.

Computed Tomographic Angiography of the Pancreas in Cats with Chronic Diabetes Mellitus Compared to Normal Cats

Background

Diabetes mellitus (DM) is a common endocrinopathy in cats. No known diagnostic test or patient characteristic at the time of diagnosis can predict likely disease course, unlike in people in whom computed tomographic angiography (CTA) is used. No published data exist regarding the CTA appearance of the pancreas in cats with DM, and thus, it is unknown what if any CTA variables should be further assessed for associations with pancreatic endocrine function.

Hypothesis/Objectives

A significant difference in pancreatic attenuation, volume, and size will be identified between normal cats and those with chronic DM on CTA.

Animals

Ten healthy control cats and 15 cats with naturally occurring DM present for >12 months.

Methods

Prospective cross‐sectional study comparing pancreatic attenuation, enhancement pattern, size, volume, pancreatic volume‐to‐body weight ratio (V:BW), pancreatic arterial: portal phase ratio (A:P), time‐to‐arterial enhancement, and time‐to‐peak portal enhancement on CTA between sedated healthy control cats and those with chronic DM.

Results

The pancreas in cats with chronic DM was significantly larger, had higher volume, higher V:BW, and shorter time‐to‐peak portal enhancement on CTA when compared to normal cats.

Conclusions and Clinical Importance

Peak portal enhancement time, pancreatic size, pancreatic volume, and V:BW can be used to differentiate normal sedated cats from those with chronic DM by CTA. These variables warrant further investigation to identify possible associations with endocrine function.

Perfusion computed tomographic measurements of cerebral blood flow variables in live Holstein calves

OBJECTIVE To measure cerebral blood flow (CBF) and cerebral blood volume (CBV) by means of perfusion CT in clinically normal Holstein calves. ANIMALS 9 Holstein calves. PROCEDURES Each of the 9 calves (mean age, 20.2 days) was anesthetized and received an injection of iodinated contrast medium into the right jugular vein at a rate of 4.0 mL/s. Dynamic CT scanning of the head at a level that included the mandibular condyle was initiated at the time of the contrast medium injection and continued for 100 seconds. A deconvolution method was used as an analytic algorithm. RESULTS Among the 9 calves, the mean ± SD CBF in the cerebral cortex, white matter, and thalamus was 44.3 ± 10.3 mL/100 g/min, 36.1 ± 7.5 mL/100 g/min, and 40.3 ± 7.5 mL/100 g/min, respectively. The CBF in white matter was significantly lower than that in the cerebral cortex or thalamus. The mean CBV in the cerebral cortex, white matter, and thalamus was 6.8 ± 1.0 mL/100 g, 5.2 ± 1.0 mL/100 g, and 5.7 ± 0.7 mL/100 g, respectively. The CBV in the cerebral cortex was significantly higher than that in the white matter or thalamus. CONCLUSIONS AND CLINICAL RELEVANCE Measurement of CBF and CBV in clinically normal calves by means of perfusion CT was feasible. The data obtained may be useful as baseline values for use in future research or for comparison with findings from calves with CNS diseases. Investigations to determine the lower limit of blood flow at which brain function can still be restored are warranted.

Early diagnosis of pancreatic necrosis based on perfusion CT to predict the severity of acute pancreatitis

BACKGROUND

Perfusion CT can diagnose pancreatic necrosis in early stage of severe acute pancreatitis, accurately. However, no study to date has examined whether early diagnosis of pancreatic necrosis is useful in predicting persistent organ failure (POF).

METHODS

We performed a multi-center prospective observational cohort study to investigate whether perfusion CT can predict the development of POF in the early stage of AP, based on early diagnosis of the development of pancreatic necrosis (PN). From 2009 to 2012, we examined patients showing potential early signs of severe AP (n = 78) on admission. Diagnoses for the development of PN were made prospectively by on-site physicians on the admission based on perfusion CT (diagnosis 1). Blinded retrospective reviews were performed by radiologists A and B, having 8 and 13 years of experience as radiologists (diagnosis 2 and 3), respectively. Positive diagnosis for the development of PN were assumed equivalent to positive predictions for the development of POF. We then calculated the area under the curve (AUC) of the receiver operating characteristic for POF predictions.

RESULTS

Fourteen (17.9%) and 23 patients (29.5%) developed PN and POF, respectively. For diagnoses 1, 2, and 3, AUCs for POF predictions were 74, 68, and 73, respectively.

CONCLUSIONS

Perfusion CT diagnoses pancreatic necrosis and on that basis predicts the development of POF; http://www.umin.ac.jp/ctr/index-j.htm,UMIN000001926 .

Perfusion CT - Can it resolve the pancreatic carcinoma versus mass forming chronic pancreatitis conundrum?

OBJECTIVES

To evaluate the utility of perfusion CT (PCT) in differentiating pancreatic adenocarcinoma from mass forming chronic pancreatitis (MFCP).

METHODS

In this ethically approved study, PCT was performed in 122 patients with pancreatic masses of which 42 patients had pancreatic adenocarcinoma and 13 had MFCP on histopathology. Perfusion parameters studied included blood flow (BF), blood volume (BV), permeability surface area product (PS), time to peak (TTP), peak enhancement intensity (PEI) and mean transit time (MTT). Twenty five controls with no pancreatic pathology were also studied.

RESULTS

Amongst the perfusion parameters BF and BV were found to be the most reliable for differentiating between adenocarcinoma and mass forming pancreatitis. Although they were reduced in both pancreatic adenocarcinoma (BF- 16.6 ± 13.1 ml/100 ml/min and BV- 5 ± 3.5 ml/100 ml) and MFCP (BF- 30.4 ± 8.7 ml/100 ml/min and BV- 8.9 ± 3.1 ml/100 ml) as compared to normal controls (BF- 94.1 ± 24 ml/100 ml/min and BV- 36 ± 10.7 ml/100 ml) but the extent of reduction was greater in pancreatic adenocarcinoma than in MFCP. Based on ROC analysis cut off values of 19.1 ml/100 ml/min for BF and 5 ml/100 ml for BV yielded optimal sensitivity and specificity for differentiating pancreatic adenocarcinoma from MFCP.

CONCLUSIONS

PCT may serve as an additional paradigm for differentiating pancreatic adenocarcinoma from mass forming chronic pancreatitis and a useful tool for detecting masses which are isodense on conventional CT.

Unrecognized necrosis at same admission cholecystectomy for pancreatitis increases organ failure and infected necrosis

BACKGROUND AND AIMS

Guidelines recommend same admission cholecystectomy (SAC) in the management of mild acute gallstone pancreatitis (AGP) with a recent randomized trial supporting this recommendation. However, the push for early cholecystectomy will lead a subset of patients with evolving, unrecognized necrotizing pancreatitis (NP) to undergo laparoscopic cholecystectomy (LC) with unknown consequences. With concerns about potentially serious outcomes, we studied the outcomes in patients with unrecognized NP who underwent SAC and identified predictors of unrecognized NP at the time of SAC.

METHODS

Retrospective study of patients who appeared to have mild AGP but subsequently discovered to have unrecognized NP after SAC (study group). Outcomes were compared to a similar cohort with necrotizing AGP who did not undergo SAC (control group 1). Predictors for unrecognized NP at the time of SAC were identified through logistic regression using a second control group with truly mild AGP undergoing SAC.

RESULTS

Patients in the study group (N = 46) undergoing SAC demonstrated higher rates of persistent organ failure (p = 0.0003), infected necrosis (p = 0.02), and length of hospital stay (p = 0.049) compared to a similar group (N = 48) with necrotizing AGP who did not undergo SAC. Persistent SIRS (p < 0.0001) and WBC >12 × 10⁹/L (p < 0.0001) on the day of cholecystectomy were associated with evolving/unrecognized NP.

CONCLUSIONS

Unrecognized NP at the time of SAC is associated with increased rates of subsequent persistent organ failure, infected necrosis, and length of hospital stay. Persistent leukocytosis and SIRS at the time of proposed cholecystectomy are predictive of unrecognized NP and should prompt contrast enhanced CT prior to proceeding with LC.

Acute pancreatitis as a complication of childhood cancer treatment

Acute pancreatitis (AP) is now well recognized as a possible complication of childhood cancer treatment, interrupting the chemotherapy regimen, and requiring prolonged hospitalization, possibly with intensive care and surgical intervention, thereby compromising the effect of chemotherapy and the remission of the underlying malignant disease. This review summarizes the current literature and presents the various etiological factors for AP during chemotherapy as well as modern trends in the diagnosis and therapy of AP in children.

Perfusion-CT--Can We Predict Acute Pancreatitis Outcome within the First 24 Hours from the Onset of Symptoms?

PURPOSE

Severe acute pancreatitis (AP) is still a significant clinical problem which is associated with a highly mortality. The aim of this study was the evaluation of prognostic value of CT regional perfusion measurement performed on the first day of onset of symptoms of AP, in assessing the risk of developing severe form of acute pancreatitis.

MATERIAL AND METHODS

79 patients with clinical symptoms and biochemical criteria indicative of acute pancreatitis (acute upper abdominal pain, elevated levels of serum amylase and lipase) underwent perfusion CT within 24 hours after onset of symptoms. The follow-up examinations were performed after 4-6 days to detect progression of the disease. Perfusion parameters were compared in 41 people who developed severe form of AP (pancreatic and/or peripancreatic tissue necrosis) with parameters in 38 consecutive patients in whom course of AP was mild. Blood flow, blood volume, mean transit time and permeability surface area product were calculated in the three anatomic pancreatic subdivisions (head, body and tail). At the same time the patient's clinical status was assessed by APACHE II score and laboratory parameters such as CRP, serum lipase and amylase, AST, ALT, GGT, ALP and bilirubin were compared.

RESULTS

Statistical differences in the perfusion parameters between the group of patients with mild and severe AP were shown. Blood flow, blood volume and mean transit time were significantly lower and permeability surface area product was significantly higher in patients who develop severe acute pancreatitis and presence of pancreatic and/or peripancreatic necrosis due to pancreatic ischemia. There were no statistically significant differences between the two groups in terms of evaluated on admission severity of pancreatitis assessed using APACHE II score and laboratory tests.

CONCLUSIONS

CT perfusion is a very useful indicator for prediction and selection patients in early stages of acute pancreatitis who are at risk of developing pancreatic and/or peripancreatic necrosis already on the first day of the onset of symptoms and can be used for treatment planning and monitoring of therapy of acute pancreatitis. Early suspicion of possible pancreatic necrosis both on the basis of scores based on clinical status and laboratory tests have low predictive value.

Epidural anesthesia improves pancreatic perfusion and decreases the severity of acute pancreatitis

AIM: To study the safety of epidural anesthesia (EA), its effect on pancreatic perfusion and the outcome of patients with acute pancreatitis (AP).

METHODS: From 2005 to August 2010, patients with predicted severe AP [Ranson score ≥ 2, C-reactive protein > 100 or necrosis on computed tomography (CT)] were prospectively randomized to either a group receiving EA or a control group treated by patient controlled intravenous analgesia. Pain management was evaluated in the two groups every eight hours using the visual analog pain scale (VAS). Parameters for clinical severity such as length of hospital stay, use of antibiotics, admission to the intensive care unit, radiological/clinical complications and the need for surgical necrosectomy including biochemical data were recorded. A CT scan using a perfusion protocol was performed on admission and at 72 h to evaluate pancreatic blood flow. A significant variation in blood flow was defined as a 20% difference in pancreatic perfusion between admission and 72 h and was measured in the head, body and tail of the pancreas.

RESULTS: We enrolled 35 patients. Thirteen were randomized to the EA group and 22 to the control group. There were no differences in demographic characteristics between the two groups. The Balthazar radiological severity score on admission was higher in the EA group than in the control group (mean score 4.15 ± 2.54 vs 3.38 ± 1.75, respectively, P = 0.347) and the median Ranson scores were 3.4 and 2.7 respectively (P = NS). The median duration of EA was 5.7 d, and no complications of the epidural procedure were reported. An improvement in perfusion of the pancreas was observed in 13/30 (43%) of measurements in the EA group vs 2/27 (7%) in the control group (P = 0.0025). Necrosectomy was performed in 1/13 patients in the EA group vs 4/22 patients in the control group (P = 0.63). The VAS improved during the first ten days in the EA group compared to the control group (0.2 vs 2.33, P = 0.034 at 10 d). Length of stay and mortality were not statistically different between the 2 groups (26 d vs 30 d, P = 0.65, and 0% for both respectively).

CONCLUSION: Our study demonstrates that EA increases arterial perfusion of the pancreas and improves the clinical outcome of patients with AP.

Acute Pancreatitis-Progress and Challenges: A Report on an International Symposium

An international symposium entitled "Acute pancreatitis: progress and challenges" was held on November 5, 2014 at the Hapuna Beach Hotel, Big Island, Hawaii, as part of the 45th Anniversary Meeting of the American Pancreatic Association and the Japanese Pancreas Society. The course was organized and directed by Drs. Stephen Pandol, Tooru Shimosegawa, Robert Sutton, Bechien Wu, and Santhi Swaroop Vege. The symposium objectives were to: (1) highlight current issues in management of acute pancreatitis, (2) discuss promising treatments, (3) consider development of quality indicators and improved measures of disease activity, and (4) present a framework for international collaboration for development of new therapies. This article represents a compilation and adaptation of brief summaries prepared by speakers at the symposium with the purpose of broadly disseminating information and initiatives.

Evaluation of Tumor-associated Stroma and Its Relationship with Tumor Hypoxia Using Dynamic Contrast-enhanced CT and (18)F Misonidazole PET in Murine Tumor Models

PURPOSE

To determine the relationship between the fractional interstitial volume (Fis), as calculated at dynamic contrast material-enhanced (DCE) computed tomography (CT), and tumor-associated stroma and to analyze its spatial relationship with tumor hypoxia in several xenograft tumor models.

MATERIALS AND METHODS

All animal experiments were approved by the animal research committee. Mice with three different xenograft tumors (U251, CFPAC-1, and BxPC-3; n = 6, n = 8, and n = 6, respectively) underwent DCE CT then hypoxia imaging with fluorine 18 ((18)F) fluoromisonidazole (FMISO) positron emission tomography (PET) within 24 hours. Immunohistochemical analysis was performed in harvested tumors to detect hypoxia markers and to quantify microvascular and stromal density. Two DCE CT parameters (amount of interstitial space associated with the amount of stroma [Fis] and flow velocity [Fv]) were identified and quantitatively validated by using immunohistochemistry. FMISO uptake within the tumor was also assessed in relation to DCE CT parameters. Imaging and immunohistochemical parameters were assessed by using the Kruskal-Wallis test, Wilcoxon rank-sum test with Bonferroni correction, and Pearson correlation coefficient.

RESULTS

Almost no α-smooth muscle actin-positive cells were found in the U251 xenograft, while abundant stroma was found in the entire BxPC-3 xenograft and in the periphery of the CFPAC-1 xenograft. Quantitative analysis showed a significant correlation (R = 0.83, P < .0001) between Fis and stromal density. FMISO uptake had a negative correlation with Fis (R = -0.58, P < .0001) and Fv (R = -0.53, P < .0001).

CONCLUSION

DCE CT can be used to quantify parameters associated with tumor-associated stroma. Tumor hypoxia was Complementarily localized in tumor-associated stroma in these models.

Treating acute pancreatitis: what's new?

The medical treatment of acute pancreatitis continues to focus on supportive care, including fluid therapy, nutrition, and antibiotics, all of which will be critically reviewed. Pharmacologic agents that were previously studied were found to be ineffective likely due to a combination of their targets and flaws in trial design. Potential future pharmacologic agents, particularly those that target intracellular calcium signaling, as well as considerations for trial design will be discussed. As the incidence of acute pancreatitis continues to increase, greater efforts will be needed to prevent hospitalization, readmission and excessive imaging in order to reduce overall healthcare costs. Primary prevention continues to focus on post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis and secondary prevention on cholecystectomy for biliary pancreatitis as well as alcohol and smoking abstinence.

Perfusion CT: can it predict the development of pancreatic necrosis in early stage of severe acute pancreatitis?

PURPOSE

Pancreatic necrosis is an important determinant of patient outcome in severe acute pancreatitis (SAP). This prospective study was conducted to evaluate if perfusion CT (PCT) can predict the development of necrosis at an early stage in SAP.

METHODS

PCT was performed within 72 h of abdominal pain in 57 consecutive admitted patients of acute pancreatitis, out of which four patients were excluded. Thirty-two patients were classified as SAP and 21 as mild acute pancreatitis (MAP) on the basis of APACHE II or SIRS criteria or presence of organ failure. All patients underwent a follow-up CECT at 3 weeks to look for pancreatic necrosis.

RESULTS

Out of 32 patients of SAP, 14 patients showed perfusion defects. The mean blood flow (BF) in these areas was 11.47 ± 5.56 mL/100 mL/min and median blood volume (BV) was 3.92 mL/100 mL (0.5-8.49 mL/100 mL). All these patients developed necrosis on follow-up scan. Two patients who did not show perfusion defects also developed necrosis. Remaining 37 patients (16 SAP and 21 MAP) did not show perfusion defect and did not develop necrosis on follow-up. All regions showing BF less than ≤23.45 mL/100 mL/min and BV ≤8.49 mL/100 mL developed pancreatic necrosis. The values of perfusion parameters may vary with the scanner, mathematical model and protocol used. The sensitivity and specificity of PCT for predicting pancreatic necrosis were 87.5% and 100%, respectively. The cut off values of BF and BV for predicting the development of pancreatic necrosis were 27.29 mL/100 mL/min and 8.96 mL/100 mL, respectively, based on ROC curve. PCT is a reliable tool for early prediction of pancreatic necrosis, which may open new avenues to prevent this ominous complication.

Pancreatic perfusion data and post-pancreaticoduodenectomy outcomes

BACKGROUND

Precise risk assessment for postoperative pancreatic fistula (POPF) after pancreaticoduodenectomy (PD) may be facilitated using imaging modalities. Computed tomography perfusion (CTP) of the pancreas may represent histologic findings. This study aimed to evaluate the utility of CTP data for the risk of POPF after PD, in relation to histologic findings.

METHODS

Twenty patients who underwent preoperative pancreatic CTP measurement using 320-detector row CT before PD were investigated. Clinicopathologic findings, including CTP data, were analyzed to assess the occurrence of POPF. In addition, the correlation between CTP data and histologic findings was evaluated.

RESULTS

POPF occurred in 11 cases (grade A, 6; grade B, 5; and grade C, 0). In CTP data, both high arterial flow (AF) and short mean transit time (MTT) were related to POPF occurrence (P = 0.001, P = 0.001). AF was negatively correlated with fibrosis in the pancreatic parenchyma (r = -0.680), whereas MTT was positively correlated with fibrosis (r = 0.725). AF >80 mL/min/100 mL and MTT <16 s showed high sensitivity, specificity, positive predictive value, and negative predictive value (80.0%, 100.0%, 100.0%, and 83.3%, respectively) for the occurrence of POPF.

CONCLUSIONS

CTP data for the pancreas were found to be correlated with the occurrence of POPF after PD. Alterations in the blood flow to the remnant pancreas may reflect histological changes, including fibrosis in the pancreatic stump, and influence the outcome after PD. CTP may thus facilitate objective and quantitative risk assessment of POPF after PD.

Perfusion in the tissue surrounding pancreatic cancer and the patient's prognosis

OBJECTIVE

The objective was to investigate the relationship between prognosis in case of pancreatic cancer and perfusion in tissue surrounding pancreatic cancer using perfusion CT.

METHODS

We enrolled 17 patients diagnosed with inoperable pancreatic adenocarcinoma. All patients were examined by perfusion CT and then underwent chemotherapy using gemcitabine. The time density curve (TDC) of each CT pixel was analyzed to calculate area under the curve (AUC) and blood flow (BF) using a mathematical algorithm based on the single-compartment model. To measure the AUC and BF of tumor (AUCT and BFT) and peritumoral tissue (AUCPTT and BFPTT), regions of interest were manually placed on the cancer and in pancreatic tissue within 10 mm of proximal pancreatic parenchyma. Survival days from the date of perfusion CT were recorded. Correlation between AUC or BF and survival days was assessed.

RESULTS

We found a significant correlation between AUCPTT or BFPTT and survival days (P = 0.04 or 0.0005). Higher AUCPTT or BFPTT values were associated with shorter survival. We found no significant correlation between AUCT or BFT and survival.

CONCLUSIONS

Our results suggest that assessments of perfusion in pancreatic tissue within 10 mm of proximal pancreatic parenchyma may be useful in predicting prognosis.

Elevation of intra-abdominal pressure by pneumoperitoneum decreases pancreatic perfusion in an in vivo porcine model

BACKGROUND

The goal of this study is to examine changes in pancreatic perfusion due to pneumoperitoneum using perfusion CT in vivo.

METHODS

Three pigs were studied. Under general anesthesia, pneumoperitoneum was induced to 16 mm Hg. Perfusion CT scans were acquired at a rate of 1 image per 2 seconds for 60 seconds. Scans were repeated 5 days later without pneumoperitoneum using the same protocol, in the same animals. The time density curve, color map, peak enhancement, time to peak, blood flow, blood volume, and permeability were evaluated.

RESULTS

In the presence of pneumoperitoneum, peak enhancement in radiodensity was decreased and time to peak was increased, and both blood flow and blood volume decreased. However, there was no consistent change in permeability observed.

CONCLUSION

This study demonstrates that pneumoperitoneum quantitatively results in decreased blood flow and blood volume to the pancreas in an in vivo animal model.

Whole-organ CT perfusion of the pancreas: impact of iterative reconstruction on image quality, perfusion parameters and radiation dose in 256-slice CT-preliminary findings

Background

This study was performed to assess whether iterative reconstruction can reduce radiation dose while maintaining acceptable image quality, and to investigate whether perfusion parameters vary from conventional filtered back projection (FBP) at the low-tube-voltage (80-kVp) during whole-pancreas perfusion examination using a 256-slice CT.

Methods

76 patients with known or suspected pancreatic mass underwent whole-pancreas perfusion by a 256-slice CT. High- and low-tube-voltage CT images were acquired. 120-kVp image data (protocol A) and 80-kVp image data (protocol B) were reconstructed with conventional FBP, and 80-kVp image data were reconstructed with iDose⁴ (protocol C) iterative reconstruction. The image noise; contrast-to-noise ratio (CNR) relative to muscle for the pancreas, liver, and aorta; and radiation dose of each protocol were assessed quantitatively. Overall image quality was assessed qualitatively. Among 76 patients, 23 were eventually proven to have a normal pancreas. Perfusion parameters of normal pancreas in each protocol including blood volume, blood flow, and permeability-surface area product were measured.

Results

In the quantitative study, protocol C reduced image noise by 36.8% compared to protocol B (P<0.001). Protocol C yielded significantly higher CNR relative to muscle for the aorta, pancreas and liver compared to protocol B (P<0.001), and offered no significant difference compared to protocol A. In the qualitative study, protocols C and A gained similar scores and protocol B gained the lowest score for overall image quality (P<0.001). Mean effective doses were 23.37 mSv for protocol A and 10.81 mSv for protocols B and C. There were no significant differences in the normal pancreas perfusion values among three different protocols.

Conclusion

Low-tube-voltage and iDose⁴ iterative reconstruction can dramatically decrease the radiation dose with acceptable image quality during whole-pancreas CT perfusion and have no significant impact on the perfusion parameters of normal pancreas compared to the conventional FBP reconstruction using a 256-slice CT scanner.

Predictors of adverse outcomes in acute pancreatitis: new horizons

Acute pancreatitis (AP) continues to be a clinical challenge. The mortality of patients with AP with adverse outcomes like organ failure and infected necrosis can be as high as 43 %. Highly accurate predictors of adverse outcomes are necessary to identify the high-risk patients so that they can be meticulously monitored and managed. However, there are no ideal predictors till date. Over the past several years, a number of single- and multi-parameter predictors have been identified and tested for prediction of adverse outcomes in AP. Out of the different tools tested, blood urea nitrogen and the harmless acute pancreatitis score appears to be useful and feasible in the management of AP under Indian conditions. Other single-parameter predictors like serum creatinine, hematocrit, erythrocyte sedimentation rate, C-reactive protein, and D-dimer need to be put to further tests in high-quality prospective studies with large sample size at the community level. Multi-parameter prediction tools like the bedside index of severity of acute pancreatitis may not be appealing in day-to-day clinical practice.

Early detection of low enhanced pancreatic parenchyma by contrast-enhanced computed tomography predicts poor prognosis of patients with acute pancreatitis

OBJECTIVES

The usefulness of early severity assessment of acute pancreatitis (AP) by contrast-enhanced computed tomography (CECT) was investigated.

METHODS

Data were obtained from a 2007 nationwide survey in Japan. Clinical data of 983 patients with AP were analyzed. All were examined by CECT on the day of admission.

RESULTS

Early findings of CECT demonstrated that low enhanced pancreatic parenchyma (LEPP) was associated with the incidence of organ failure (OF), multiple OF, and infectious complications as well as mortality (P < 0.0001). Next, patients were further divided into 4 groups according to the CECT findings, which focused on the LEPP and peripancreatic collections (PPCs). The LEPP/PPC (+/+) group was characterized as high morbidity and high mortality. The incidence of OF (28.2%), multiple OF (15.5%), and mortality (11.4%) in patients assigned to the (+/+) group was significantly higher than in those assigned to the other groups. The incidence of infectious complications was significantly higher in patients assigned to the (+/+) group (16.7%), the (+/-) group (9.0%), and the (-/+) group (7.0%) than those assigned to the (-/-) group (1.8%).

CONCLUSIONS

The detection of LEPP and PPC was a useful CECT finding for the early assessment of the severity of AP.

Computed tomography perfusion analysis of pancreatic carcinoma

OBJECTIVE

The purpose of this study was to evaluate CT perfusion of pancreatic carcinomas using the Patlak model for assessing perfusion, permeability, and blood volume.

METHODS

A total of 25 patients with pancreatic carcinoma were examined prospectively with a 64-slice computed tomography (CT) using a dynamic sequence after intravenous injection of 80-mL contrast material (370 mg/mL; flow rate, 5 mL/s). Eighty-kilovolt (peak) perfusion acquisitions were evaluated for estimating perfusion parameters for carcinoma and healthy tissue using a 2-compartment model (Patlak model).

RESULTS

Twenty patients had hypodense tumors; in 5 patients, the tumor could not be delineated in contrast-enhanced CT. All carcinomas could be identified clearly in the color-coded perfusion maps. Perfusion, permeability, and blood volume values were significant lower in pancreatic carcinomas compared to healthy pancreatic tissue (0.27 ± 0.20 vs 0.89 ± 0.19 min, P < 0.0001; 0.43 ± 0.20 vs 0.75 ± 0.16 × 0.5 min, P < 0.0001; and 38.9 ± 20.7 vs 117.8 ± 46.9 mL/100 mL, P < 0.0001).

CONCLUSION

Computed tomographic perfusion of the pancreas using a 2-compartment perfusion model is feasible. Color-coded perfusion maps could be a helpful tool to delineate pancreatic carcinomas even if they are not visible in contrast-enhanced CT.

Assessment of Chronic Pancreatitis: Use of Whole Pancreas Perfusion With 256-Slice Computed Tomography

OBJECTIVE: We aimed to compare perfusion computed tomography (CTP) characteristics of the normal pancreas with those of chronic pancreatitis (CP) and to examine the possibility of evaluating pancreatic exocrine function with CTP. METHODS: Thirty-two patients (control group, n = 18; CP group, n = 14) who completed the whole pancreas CT perfusion examination with 256-slice CT were studied. Four parameters, including perfusion (PF), peak enhancement intensity (PEI), time-to-peak (TTP), and blood volume (BV), were measured and compared between the control and CP groups, and between patients with and without exocrine pancreatic insufficiency (EPI) in the CP group. Pancreatic exocrine function was determined via serum trypsinogen. RESULTS: There was no significant difference between the distribution of PF, PEI, and BV in different pancreas regions, namely, the head, body, and tail (P > 0.05). PF, PEI, and BV of the CP group were significantly decreased, and TTP was significantly increased compared with the control group (P < 0.05). A significant decrease of PF, PEI, and BV and increase of TTP were observed in patients with EPI than in patients without EPI (P < 0.05). CONCLUSIONS: Perfusion CT is an appropriate imaging technique to diagnose CP and may be useful as a screening test to rule out early EPI.

Pancreatic Perfusion CT in Early Stage of Severe Acute Pancreatitis

Early intensive care for severe acute pancreatitis is essential for improving SAP mortality rates. However, intensive therapies for SAP are often delayed because there is no ideal way to accurately evaluate severity in the early stages. Currently, perfusion CT has been shown useful to predict prognosis of SAP in the early stage. In this presented paper, we would like to review the clinical usefulness and limitations of perfusion CT for evaluation of local and systemic complications in early stage of SAP.

Perfusão por tomografia computadorizada do abdome: aplicações clínicas, princípios e técnica do exame

Novas técnicas de exames têm sido desenvolvidas com o objetivo de se obter não apenas uma avaliação estrutural, mas também uma análise funcional e metabólica de diversos órgãos e tipos de lesões. Entre estas ferramentas, a perfusão por tomografia computadorizada (PTC) tem despertado o interesse de muitos pesquisadores em estudar a sua aplicabilidade em órgãos e doenças abdominais. Entre estas aplicações podemos citar a avaliação do comportamento biológico de tecidos sadios e doentes, a diferenciação de processos inflamatórios de tumorais e o diagnóstico da recidiva tumoral após terapêuticas minimamente invasivas. A principal característica da PTC reside na sua capacidade de caracterizar comportamentos perfusionais distintos e que traduzem alterações biológicas de determinadas lesões e tecidos doentes. Dessa forma, o nosso objetivo foi realizar uma ampla revisão da literatura, mostrando as principais técnicas e protocolos utilizados nos exames de PTC, as principais indicações, vantagens e desvantagens do método, além de propor um protocolo de exame que possa ser introduzido na rede privada e pública de saúde, com reprodutibilidade e simplicidade de implementação.

Hepatic arterial perfusion increases in the early stage of severe acute pancreatitis patients: evaluation by perfusion computed tomography

PURPOSE

Although hepatic perfusion abnormalities have been reported in patients with acute pancreatitis, hepatic perfusion with severe acute pancreatitis (SAP) has not been quantitatively evaluated in humans. Therefore, we investigated hepatic perfusion in patients with SAP using perfusion CT.

MATERIALS AND METHODS

Hepatic perfusion CT was performed in 67 patients with SAP within 3 days after symptom onset. The patients were diagnosed as having SAP according to the Atlanta criteria. Fifteen cases were established as a control group. Perfusion CT was obtained for 54s beginning with a bolus injection of 40 ml of contrast agent (600-630 mgI/kg) at a flow rate of 4 ml/s. Perfusion data were analyzed by the dual-input maximum slope method to obtain hepatic arterial perfusion (HAP) and hepatic portal perfusion (HPP). Finally, we compared HAP and HPP in SAP patients with those in the control group, respectively.

RESULTS

Average HAP was significantly higher in SAP patients than in the control group (75.1 ± 38.0 vs. 38.2 ± 9.0 ml/min/100ml; p<0.001). There was no significant difference in average HPP between SAP patients and the control group (206.7 ± 54.9 vs. 204.4 ± 38.5 ml/min/100ml; p=0.92).

CONCLUSION

Using quantitative analysis on perfusion CT, we first demonstrated an increase of HAP in the right hepatic lobe in SAP patients.

Perfusion computed tomography findings of autoimmune pancreatitis

OBJECTIVES

The aim of this study was to clarify the pancreatic blood perfusion in patients with autoimmune pancreatitis (AIP) and the changes after steroid treatment.

METHODS

Perfusion computed tomography was performed in 11 patients with AIP and 12 control subjects. Pancreatic volumetric blood flow (F(V)), volume of distribution (V(D)), and blood transit time τ were determined from a single-compartment kinetic model. Nine patients with AIP were reexamined by perfusion computed tomography after corticosteroid administration.

RESULTS

The pancreatic F(V) values of the 11 patients with AIP (82.7/min) were significantly lower than those of control subjects (163.5/min, P = 0.0006). On the other hand, the pancreatic V(D) and τ values were not significantly different between AIP and normal. After steroid treatment, the F(V) values of 9 reexamined patients with AIP (76.2/min) were significantly elevated (109.8/min, P = 0.0391). However, the changes of the values after the treatment differed in degree among individuals. The values of 4 patients were dramatically elevated to greater than 100/min, whereas those of 4 other patients did not improve well. The value of the remaining patient whose initial F(V) value was normal (168.09/min) did not change after the treatment.

CONCLUSIONS

Pancreatic volumetric perfusion was attenuated in AIP patients. The perfusion was improved after the steroid treatment.

Blood flow change quantification in cervical cancer before and during radiation therapy using perfusion CT

The purpose of this study was to quantify the changes of tumor blood flow (BF) in cervical cancer after radiation therapy by using perfusion computed tomography (CT), and to examine the difference between maximum slope (MS) and single-input one-compartment model (SOCM) methods. Fourteen consecutive patients who received definitive radiation therapy for cervical cancer from October 2009 to February 2010 were enrolled in this study. Blood flow (BF) analyses were performed using both MS and SOCM methods. Quantitative BF maps were created using Body Perfusion (Toshiba Medical Systems, Co. Tokyo, Japan). Perfusion color maps were successfully created by the two analytical methods. BF of the tumors was clearly higher than that of normal cervix, making it possible to distinguish tumor tissue from normal cervical tissue. BF of the tumors after 20 Gy of radiation therapy calculated by the MS method was significantly larger than that before treatment (126.9 vs. 72.2 ml/min/100 ml, median; p < 0.05). Although BF calculated by the MS and SOCM methods showed a positive linear correlation (p < 0.001, r = 0.981), BF calculated by the MS method was lower than that obtained by the SOCM method (103.7 vs. 115.1 ml/min/100 ml, p < 0.01). The change of tumor BF in cervical cancer before and after radiation therapy can be monitored by conducting blood flow analysis using perfusion CT. BF by the MS method was lower than that by the SOCM method, but the two analytical methods correlated well. Perfusion CT may have potential in noninvasive monitoring of vascular and oxygenation status and for guiding adaptive therapy.

Feasibility of measuring human pancreatic perfusion in vivo using imaging techniques

OBJECTIVE

The objective of this study was to demonstrate the feasibility of pancreatic perfusion computed tomography (CT) and review pancreatic perfusion measurements by various imaging modalities.

METHODS

Dynamic CT data from 8 patients (4 men; mean age, 64.8 [SD, 12.1] years; range, 40-80 years) with normal pancreas were analyzed using 2 analytical models: the maximum-slope and compartment-model methods. Literature search was also performed.

RESULTS

Although the perfusion value estimated by the maximum-slope method (88.1 [SD, 42.1] mL/min per 100 mL) was significantly smaller than that of the compartment-model method (127.0 [SD, 70.5]; P < 0.001), there was a linear correlation between them (r = 0.97, P < 0.001). In the literature review, 15 studies that reported the absolute values of normal pancreatic perfusion, by using perfusion CT, dynamic magnetic resonance imaging, hydrogen gas clearance method, and 15O-H2O-positron emission tomography were found. The reported mean values of normal pancreatic perfusion ranged from 38.4 to 356 mL/min per 100 mL, and there was a great deal of individual variation.

CONCLUSIONS

Perfusion CT may provide reliable perfusion measurements of the pancreas, and the normal value was estimated at around 100 mL/min per 100 mL with a great deal of individual variation. The maximum-slope method may provide a lower perfusion value compared with the compartment-model method.

Protocol modifications for CT perfusion (CTp) examinations of abdomen-pelvic tumors: impact on radiation dose and data processing time

PURPOSE

To evaluate the effect of CT perfusion (CTp) protocol modifications on quantitative perfusion parameters, radiation dose and data processing time.

MATERIALS & METHODS

CTp datasets of 30 patients (21M:9F) with rectal (n = 24) or retroperitoneal (n = 6) tumours were studied. Standard CTp protocol included 50 sec cine-phase (0.5 sec/rotation) and delayed-phase after 70 ml contrast bolus at 5-7 ml/sec. CTp-data was sub-sampled to generate modified datasets (n = 105) with cine-phase(n = 15) alone, varying cine-phase duration (20-40 sec, n = 45) and varying temporal sampling-interval (1-3 sec, n = 45). The estimated CTp parameters (BF,BV,MTT&PS) and radiation dose of standard CTp served as reference for comparison.

RESULTS

CTp with 50 sec cine-phase showed moderate to high correlation with standard CTp for BF&MTT (r = 0.96&0.85) and low correlation for BV (0.75, p = 0.04). Limiting cine-phase duration to 30 sec demonstrated comparable results for BF&MTT, while considerable variation in CTp values existed at 20 sec. There was moderate-to-high correlation of CTp parameters with sampling interval of 1&2 sec (r = 0.83-0.97, p > 0.05), while at 3 sec only BF showed high correlation (r = 0.96, p = 0.05). Increasing sampling interval (47-60%) and reducing cine-phase duration substantially reduced dose(30.8-65%) which paralleled reduced data processing time (3-10 min).

CONCLUSION

Limiting CTp cine-phase to 30 sec results in comparable BF&MTT values and increasing cine-phase sampling interval to 2 sec provides good correlation for all CTp parameters with substantial dose reduction and improved computational efficiency.