Perfusion computed tomography findings of autoimmune 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.

Adverse events of endoscopic ultrasound-guided fine-needle aspiration for histologic diagnosis in Japanese tertiary centers: Multicenter retrospective study

BACKGROUND AND AIMS

Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is used for the histopathological diagnosis of any type of gastrointestinal disease. Few adverse events are experienced with this procedure; however, the actual rate of adverse events remains unclear. This study aimed to clarify the current status of cases that experienced adverse events related to the EUS-FNA procedure used for histopathologic diagnoses.

METHODS

A retrospective analysis of cases with EUS-FNA-related adverse events in Japanese tertiary centers was conducted by assessing the following clinical data: basic case information, FNA technique, type of procedural adverse events, and prognosis.

RESULTS

Of the 13,566 EUS-FNA cases overall, the total number of cases in which adverse events related to EUS-FNA occurred was 234. The incidence of EUS-FNA-related adverse events was ~1.7%. Bleeding and pancreatitis cases accounted for ~49.1% and 26.5% of all adverse events, respectively. Bleeding was the most common adverse event with only seven cases requiring blood transfusion. In cases with neuroendocrine tumors, pancreatitis was the most frequent adverse event. Needle tract seeding because of EUS-FNA was observed during the follow-up period in only ~0.1% of cases with pancreatic cancer. There was no mortality because of adverse events caused by EUS-FNA.

CONCLUSIONS

This study revealed that the adverse events-related EUS-FNA for histopathologic diagnoses were not severe conditions, and had low incidence.

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.

A feasible CT feature to differentiate focal-type autoimmune pancreatitis from pancreatic ductal adenocarcinoma

BACKGROUND

To investigate whether the relative computed tomography (CT) value (rCT) of adjacent pancreatic parenchyma can distinguish focal-type autoimmune pancreatitis (fAIP) from pancreatic ductal adenocarcinoma (PDAC).

METHODS

A total of 13 patients with fAIP and 20 patients with PDAC were included in this study. The rCT was calculated as the ratio of the CT value of adjacent pancreatic parenchyma to that of muscle. The diagnostic performance of rCT for discriminating fAIP from PDAC was evaluated using receiver operating characteristic (ROC) analysis.

RESULTS

Both fAIP and PDAC presented hyper-fibrosis histologically and delayed enhancement on CT examination. Moreover, the pancreatic parenchyma of fAIP presented serious inflammation. The mean rCT of the parenchyma was significantly lower in fAIP than in PDAC in all phases. The best diagnostic performance of the rCT value was found in the pancreatic phase, with an area under the ROC curve of 0.912, while the areas under the ROC curve of the portal and delayed phases were 0.812 and 0.754, respectively. The optimal cut-off value for distinguishing fAIP from PDAC was 1.62 in the pancreatic phase.

CONCLUSIONS

The rCT of the pancreatic parenchyma during the pancreatic phase may be a feasible CT feature for differentiating fAIP from PDAC.

Early pancreatic volume reduction on CT predicts relapse in patients with type 1 autoimmune pancreatitis treated with steroids

Background

Type 1 autoimmune pancreatitis (AIP) is clinically characterized by a response to steroid therapy. Despite having a favorable prognosis, AIP has a high relapse rate and factors predicting relapse in AIP patients treated with steroids have not yet been established.

Methods

A retrospective chart review was conducted of 32 newly diagnosed type 1 AIP patients who had undergone enhanced computed tomography (CT) pre- and post-steroid therapy.

Results

Ten patients experienced relapse. Pancreatic volume was reduced significantly in all patients (pre-treatment volume, 88.5 ± 32.9 cm³ vs. post-treatment volume, 45.4 ± 21.1 cm³; P < 0.001), although the pre-treatment pancreatic volume did not differ between the relapse and non-relapse groups (92.6 ± 10.5 cm³ vs. 86.6 ± 7.1 cm³, P = 0.401). However, the post-treatment pancreatic volume was significantly greater in the relapse group than that in the non-relapse group (56.9 ± 6.3 cm³ vs. 40.2 ± 4.2 cm³, P = 0.008). Similarly, the percent reduction in pancreatic volume was significantly smaller in the relapse group than that in the non-relapse group (36.6 ± 4.7 % vs. 52.1 ± 3.2 %, P = 0.002). Multivariate analysis identified post-treatment pancreatic volume (HR, 1.04, 95 % CI: 1.01–1.08, P = 0.010) and percent reduction in pancreatic volume (HR, 0.87, 95 % CI: 0.79–0.94, P < 0.001) as predictive factors for relapse of type 1 AIP. A post-treatment pancreatic volume of 50 cm³ < (P = 0.009) and a percent reduction in the pancreatic volume of <35 % (P = 0.004) had a significantly high relapse rate. These data suggest that early pancreatic volume changes after steroid therapy may be a useful prognostic value, because type 1 AIP patients with a high post-treatment pancreatic volume or low pancreatic volume reduction showed significant relapse.

Conclusions

Early pancreatic volume reduction on CT after steroid therapy indicates the therapeutic effects of steroids, and a low decrease in the pancreatic volume may be associated with a limited response that predicts future relapse in patients with type 1 AIP. Reduction of steroids in these cases must be observed carefully with consideration of immunomodulator use.

Temporal assessment of pancreatic blood flow and perfusion following secretin stimulation using noninvasive MRI

PURPOSE

To dynamically quantify pancreatic perfusion and flow within the arteries supplying the pancreas in response to secretin stimulation.

MATERIALS AND METHODS

Twelve healthy male subjects were scanned at 1.5T with arterial spin labeling to measure tissue perfusion and phase contrast magnetic resonance imaging (MRI) to measure vessel flow. Superior mesenteric (SMA), gastroduodenal (GDA), common hepatic (HA), and splenic (SA) arterial flow and pancreatic perfusion were serially measured for 50 minutes following 1 IU/kg intravenous secretin. The significance of differences between timepoints was tested using a repeated measures one-way analysis of variance (ANOVA).

RESULTS

Baseline blood flow (mean ± SEM or median [IQR]) for SMA, HA, SA, and GDA was 7.6 ± 1.3, 4.0 ± 0.5, 8.2 ± 0.8, and 0.9 (0.8-1.4) ml/s, respectively. Baseline pancreatic perfusion was 200 ± 25 ml/100g/min. Blood flow increased in the SMA (234%, P < 0.0001) and GDA (155%, P = 0.015) immediately after secretin injection. Reduced HA blood flow was observed after 10 minutes (P = 0.066) with no change in SA flow (P = 0.533). Increased pancreatic perfusion was maintained for 40 minutes after injection with a maximal increase at 5 minutes (16.8%, P = 0.025).

CONCLUSION

Intravenous secretin resulted in significant temporal changes in pancreatic perfusion and arterial blood flow.

Amendment of the Japanese Consensus Guidelines for Autoimmune Pancreatitis, 2013 I. Concept and diagnosis of autoimmune pancreatitis

BACKGROUND

In response to the proposal of the international consensus diagnostic criteria (ICDC) for autoimmune pancreatitis (AIP) and the Japanese diagnostic criteria in 2011, the 2009 Japanese consensus guidelines for managing AIP required revision.

METHODS

Three committees [the professional committee for making clinical questions (CQs) and statements by Japanese specialists, the expert panelist committee for rating statements by the modified Delphi method, and the evaluating committee by moderators] were organized. Fifteen specialists for AIP extracted the specific clinical statements from 1,843 articles published between 1963 and 2012 (obtained from Pub Med and a secondary database, and developed the CQs and statements. The expert panel individually rated the clinical statements using a modified Delphi approach, in which a clinical statement receiving a median score greater than seven on a nine-point scale from the panel was regarded as valid.

RESULTS

The professional committee created 13 CQs and statements for the current concept and diagnosis of AIP, 6 for extra-pancreatic lesions, 6 for differential diagnosis, and 11 for treatment.

CONCLUSION

After evaluation by the moderators, amendments to the Japanese consensus guidelines for AIP have been proposed for 2013.

Recent advances in research of immunoglobulin G4-related sclerosing cholangitis

Immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) is a recently defined disease entity characterized by elevated serum IgG4, chronic progressive obstructive jaundice, and diffuse or mass-forming inflammatory reaction rich in IgG4-positive plasma cells and lymphocytes associated with fibrosclerosis and obliterative phlebitis, which shares a number of clinical, biochemical, and radiological features with primary sclerosing cholangitis (PSC) or cholangiocarcinoma (CC). IgG4-SC is commonly associated with autoimmune pancreatitis (AIP). Steroid therapy comprises the mainstay of treatment for IgG4-SC patients. However, liver transplantation is the only useful treatment for PSC patients, and CC patients require surgical therapy. Therefore, the accurate discrimination between IgG4-SC and PSC or CC is a very important issue. In this article, we will review the features and role of immunoglobulin G4 (IgG4), the diagnosis and therapy of IgG4-SC, and the relations between IgG4-SC and AIP, PSC or CC.