Pancreatic segmentation on an embryological and anatomical basis

Pancreatic head carcinoma derived from the dorsal pancreas is more likely to metastasize early than from the ventral pancreas through microvascular invasion

The development of the pancreatic head originates from the fusion of the ventral and dorsal pancreatic primordia during embryonic development. Theoretically, the origin of pancreatic head cancer also exists from the ventral pancreas and the dorsal pancreas. Among 49 patients with pancreatic head cancer, pancreatic head cancer was divided into pancreatic head cancer originating from the ventral (PHCv) or dorsal pancreas (PHCd) through imaging and pathological classification. The clinical data was collected and compared between the PHCv group and the PHCd group. The results showed that the patients from the PHCd group had worse long-term survival than those from the PHCv group (10 months vs 14.5 months). Similarly, the progression-free survival (PFS) results also indicate that patients from the PHCd group had a shorter time than those from the PHCv group (5 months vs 9.5 months). Further stratified analysis of potentially related factors showed that microvascular invasion is related to poor prognosis, and patients with pancreatic head cancer derived from the dorsal pancreas are more likely to develop microvascular invasion.

Anatomical basis for pancreas transplantation via isolated splenic artery perfusion: A literature review

The variability of vascular anatomy of the pancreas underlines the difficulty of its transplantation. Research regarding the consistency of anatomical variations shows splenic arterial dominance in most cases. This can significantly improve transplantation success. A systematic literature review was performed according to the quality standards described in the AMSTAR measurement tool and the PRISMA guidelines. We valuated existing literature regarding the vascularization and blood perfusion patterns of the pancreas in terms of dominance and variability. The collected data was independently analyzed by two researchers. Variance of vascular anatomy was seen to be underreported in literature, though significant findings have been included and discussed in this study, providing valuable insight into the dynamics of pancreatic perfusion and feasibility of transplantation on several different supplying arteries. The splenic artery (SA) has a high percentage of consistency in all found studies (over 90%). High frequency of anastomoses between arterial pools supplying the pancreas can mediate sufficient blood supply through a dominant vessel, such as the SA, which is present in most cases. Pancreatic transplantation with isolated SA blood supply can provide sufficient arterial perfusion of the pancreas for stable transplant viability due to high anatomical consistency of the SA and vast communications with other arterial systems.

The Pancreas and Known Factors of Acute Pancreatitis

Pancreatitis is regarded by clinicians as one of the most complicated and clinically challenging of all disorders affecting the abdomen. It is classified on the basis of clinical, morphological, and histological criteria. Causes of acute pancreatitis can easily be identified in 75–85% of patients. The main causes of acute, recurrent acute, and chronic pancreatitis are gallstone migration and alcohol abuse. Other causes are uncommon, controversial, or unexplained. For instance, cofactors of all forms of pancreatitis are pancreas divisum and hypertriglyceridemia. Another factor that should be considered is a complication of endoscopic retrograde cholangiopancreatography: post-endoscopic retrograde cholangiopancreatography acute pancreatitis. The aim of this study is to present the known risk factors for acute pancreatitis, beginning with an account of the morphology, physiology, and development of the pancreas.

Extensive (subtotal) distal pancreatectomy for pancreatic ductal adenocarcinoma: a propensity score matched cohort study of short- and long-term outcomes compared with those of conventional distal pancreatectomy

PURPOSE

Extensive distal pancreatectomy (ExDP) can transect the pancreatic parenchyma more from the right side than conventional distal pancreatectomy (CDP) can. This study aimed to evaluate the short- and long-term outcomes of ExDP for pancreatic ductal adenocarcinoma (PDAC) of the pancreatic body, located adjacent to the portal vein (PV).

METHODS

Medical records of 98 patients who underwent ExDP (n = 15) or CDP (n = 83) for PDAC were retrospectively reviewed. Short- and long-term outcomes of the two groups were compared. Propensity score matched analysis was additionally performed to minimize the impact of treatment allocation bias.

RESULTS

In the total cohort, the CDP group had a significantly higher proportion of pancreatic tail lesions (P < 0.01), higher proportion of males, and larger tumor size. Of the 15 patients who underwent ExDP, 11 could be matched. These differences of patients' characteristics were not observed after matching. Before and after matching, the duration of surgery, blood loss, rate of morbidity including pancreatic fistula, and postoperative course were comparable between the groups. The rate of recurrence and recurrence pattern were also not significantly different between the groups. ExDP for PDAC of the pancreatic body near the PV did not increase local or lymph node recurrence. The disease-free and overall survival did not differ between the groups.

CONCLUSIONS

Surgical and oncological outcomes after ExDP for PDAC were acceptable and comparable to those after CDP. ExDP is a feasible procedure, and could be an option for the treatment of PDAC of the pancreatic body near PV.

Pancreas MRI Segmentation Into Head, Body, and Tail Enables Regional Quantitative Analysis of Heterogeneous Disease

BACKGROUND

Quantitative imaging studies of the pancreas have often targeted the three main anatomical segments, head, body, and tail, using manual region of interest strategies to assess geographic heterogeneity. Existing automated analyses have implemented whole-organ segmentation, providing overall quantification but failing to address spatial heterogeneity.

PURPOSE

To develop and validate an automated method for pancreas segmentation into head, body, and tail subregions in abdominal MRI.

STUDY TYPE

Retrospective.

SUBJECTS

One hundred and fifty nominally healthy subjects from UK Biobank (100 subjects for method development and 50 subjects for validation). A separate 390 UK Biobank triples of subjects including type 2 diabetes mellitus (T2DM) subjects and matched nondiabetics.

FIELD STRENGTH/SEQUENCE

A 1.5 T, three-dimensional two-point Dixon sequence (for segmentation and volume assessment) and a two-dimensional axial multiecho gradient-recalled echo sequence.

ASSESSMENT

Pancreas segments were annotated by four raters on the validation cohort. Intrarater agreement and interrater agreement were reported using Dice overlap (Dice similarity coefficient [DSC]). A segmentation method based on template registration was developed and evaluated against annotations. Results on regional pancreatic fat assessment are also presented, by intersecting the three-dimensional parts segmentation with one available proton density fat fraction (PDFF) image.

STATISTICAL TEST

Wilcoxon signed rank test and Mann-Whitney U-test for comparisons. DSC and volume differences for evaluation. A P value < 0.05 was considered statistically significant.

RESULTS

Good intrarater (DSC mean, head: 0.982, body: 0.940, tail: 0.961) agreement and interrater (DSC mean, head: 0.968, body: 0.905, tail: 0.943) agreement were observed. No differences (DSC, head: P = 0.4358, body: P = 0.0992, tail: P = 0.1080) were observed between the manual annotations and our method's segmentations (DSC mean, head: 0.965, body: 0.893, tail: 0.934). Pancreatic body PDFF was different between T2DM and nondiabetics matched by body mass index.

DATA CONCLUSION

The developed segmentation's performance was no different from manual annotations. Application on type 2 diabetes subjects showed potential for assessing pancreatic disease heterogeneity.

LEVEL OF EVIDENCE

4 TECHNICAL EFFICACY STAGE: 3.

Endocrine and Metabolic Insights from Pancreatic Surgery

Although it is well established that diabetes can also develop as a result of diseases or maneuvers on the exocrine pancreas, the complex relationship between glucose disorders and underlying pancreatic disease is still debated. There is evidence that several features linked to pancreatic diseases can modify endocrine and metabolic conditions before and after surgery. However, pancreatic surgery provides a rare opportunity to correlate in vivo endocrine and metabolic pathways with ex vivo pancreatic samples, to examine the endocrine and metabolic effects of acute islet removal, and finally to clarify the pathogenesis of diabetes. This approach could therefore represent a unique method to shed light on the molecular mechanisms, predicting factors, and metabolic consequences of insulin resistance, islet plasticity, β cell failure, and type 2 diabetes.

Exploration of peripancreatic lymphatic pathways in a live porcine model

Pancreatic cancer is associated with a poor prognosis, mainly due to lymph node invasion and lymph node recurrence after surgical resection, even after extended lymphadenectomy. The peripancreatic lymphatic system is highly complex and the specific lymphatic drainage of each part of the pancreas has not been established. The aim of this study was to determine the lymphatic drainage pathways specific to each part of the pancreas on live pigs using Patent Blue. The pancreases of 14 live pigs were injected in different parts of the gland. The technique was efficient and reproducible. The diffusion patterns were similar for each location and were reported. Our results in pigs allowed us to define specific nodal relay stations and lymphatic drainage for each part of the pancreas and confirm that independent anatomical-surgical pancreatic segments can be described. It is interesting to note that lymphatic drainage for the upper part of the proximal part of pancreas (duodenal lobe) occurred on the left side of the portal vein. This suggests that lymph node resection during cephalic duodenopancreatectomy in humans should be extended to the left side of the mesenteric vein, and probably to the right side of the superior mesenteric artery, as recently suggested. These results could help surgeons perform safe anatomical-segmental pancreatic resections with accurate lymphadenectomies and improve survival in patients with pancreatic cancer. Based on these results we will perform an innovative prospective study. Patent Blue will be injected into different parts of the gland in patients operated for pancreatic resection, and lymphatic diffusion of the dye will be recorded in relation to their origin from the theoretical pancreatic segments (ClinicalTrials.gov Identifier: NCT03597230).

Pancreatic Blood Flow with Special Emphasis on Blood Perfusion of the Islets of Langerhans

The pancreatic islets are more richly vascularized than the exocrine pancreas, and possess a 5- to 10-fold higher basal and stimulated blood flow, which is separately regulated. This is reflected in the vascular anatomy of the pancreas where islets have separate arterioles. There is also an insulo-acinar portal system, where numerous venules connect each islet to the acinar capillaries. Both islets and acini possess strong metabolic regulation of their blood perfusion. Of particular importance, especially in the islets, is adenosine and ATP/ADP. Basal and stimulated blood flow is modified by local endothelial mediators, the nervous system as well as gastrointestinal hormones. Normally the responses to the nervous system, especially the parasympathetic and sympathetic nerves, are fairly similar in endocrine and exocrine parts. The islets seem to be more sensitive to the effects of endothelial mediators, especially nitric oxide, which is a permissive factor to maintain the high basal islet blood flow. The gastrointestinal hormones with pancreatic effects mainly influence the exocrine pancreatic blood flow, whereas islets are less affected. A notable exception is incretin hormones and adipokines, which preferentially affect islet vasculature. Islet hormones can influence both exocrine and endocrine blood vessels, and these complex effects are discussed. Secondary changes in pancreatic and islet blood flow occur during several conditions. To what extent changes in blood perfusion may affect the pathogenesis of pancreatic diseases is discussed. Both type 2 diabetes mellitus and acute pancreatitis are conditions where we think there is evidence that blood flow may contribute to disease manifestations. © 2019 American Physiological Society. Compr Physiol 9:799-837, 2019.

Parenchyma-Sparing, Limited Pancreatic Head Resection for Benign Tumors and Low-Risk Periampullary Cancer--a Systematic Review

BACKGROUND

Parenchyma-sparing local extirpation of benign tumors of the pancreatic head provides the potential benefits of preservation of functional tissue and low postoperative morbidity.

METHODS

Medline/PubMed, Embase, and Cochrane library databases were surveyed for studies performing limited resection of the pancreatic head and resection of a segment of the duodenum and common bile duct or preservation of the duodenum and common bile duct (CBD). The systematic analysis included 27 cohort studies that reported on limited pancreatic head resections for benign tumors. In a subgroup analysis, 12 of the cohort studies were additionally evaluated to compare the postoperative morbidity after total head resection including duodenal segment resection (DPPHR-S) and total head resection conserving duodenum and CBD (DPPHR-T).

RESULTS

Three hundred thirty-nine of a total of 503 patients (67.4%) underwent total head resections. One hundred forty-seven patients (29.2%) of them underwent segmental resection of the duodenum and CBD (DPPHR-S) and 192 patients (38.2%) underwent preservation of duodenum and CBD. One hundred sixty-four patients experienced partial head resection (32.6%). The final histological diagnosis revealed in 338 of 503 patients (67.2%) cystic neoplasms, 53 patients (10.3%) neuroendocrine tumors, and 20 patients (4.0%) low-risk periampullary carcinomas. Severe postoperative complications occurred in 62 of 490 patients (12.7%), pancreatic fistula B + C in 40 of 295 patients (13.6%), resurgery was experienced in 2.7%, and delayed gastric emptying in 12.3%. The 90-day mortality was 0.4%. The subgroup analysis comparing 143 DPPHR-S patients with 95 DPPHR-T patients showed that the respective rates of procedure-related biliary complications were 0.7% (1 of 143 patients) versus 8.4% (8 of 95 patients) (p ≤ 0.0032), and rates of duodenal complications were 0 versus 6.3% (6 of 95 patients) (p ≤ 0.0037). DPPHR-S was associated with a higher rate of delay of gastric emptying compared to DPPHR-T (18.9 vs. 2.1%, p ≤ 0.0001).

CONCLUSION

Parenchyma-sparing, limited head resection for benign tumors preserves functional pancreatic and duodenal tissue and carries in terms of fistula B + C rate, resurgery, rehospitalization, and 90-day mortality a low risk of postoperative complications. A subgroup analysis exhibited after total pancreatic head resection that preserves the duodenum and CBD an association with a significant increase in procedure-related biliary and duodenal complications compared to total head resection combined with resection of the periampullary segment of the duodenum and resection of the intrapancreatic CBD.

Imaging of the pancreatic duct by linear endoscopic ultrasound

The current gold standard investigation for anatomic exploration of the pancreatic duct (PD) is endoscopic retrograde cholangiopancreatography. Magnetic resonance cholangiopancreatography is a noninvasive method for exploration of the PD. A comprehensive evaluation of the course of PD and its branches has not been described by endoscopic ultrasound (EUS). In this article, we describe the techniques of imaging of PD using linear EUS.

Structural similarities and differences between the human and the mouse pancreas

Mice remain the most studied animal model in pancreas research. Since the findings of this research are typically extrapolated to humans, it is important to understand both similarities and differences between the 2 species. Beside the apparent difference in size and macroscopic organization of the organ in the 2 species, there are a number of less evident and only recently described differences in organization of the acinar and ductal exocrine tissue, as well as in the distribution, composition, and architecture of the endocrine islets of Langerhans. Furthermore, the differences in arterial, venous, and lymphatic vessels, as well as innervation are potentially important. In this article, the structure of the human and the mouse pancreas, together with the similarities and differences between them are reviewed in detail in the light of conceivable repercussions for basic research and clinical application.

Head dorsal pancreatectomy: an alternative to the pancreaticoduodenectomy for not enucleable benign or low-grade malignant lesions

BACKGROUND

Head dorsal pancreatectomy (HDP) is a segmental pancreatic resection, conservative variant of total dorsal pancreatectomy, applied to preserve the functional pancreatic parenchyma as an alternative to pancreaticoduodenectomy in not enucleable benign or low-grade malignant lesions. The absences of biliary and gastrointestinal resection/reconstruction are the other advantages of the technique.

METHODS

We reported a case of HDP performed in a female 39-year-old patient for a neuroendocrine tumour of the dorsal portion of the pancreatic head.

RESULTS

The superior mesenteric vein was dissected from the pancreatic neck. The pancreas was transected at the left margin of the superior mesenteric vein. After identification and mobilisation of gastroduodenal artery and the anterior superior pancreatico-duodenal artery, the head dorsal segment was dissected stepwise from the duodenal wall toward the common bile duct plane; the dissection of the pancreatic parenchyma was completed along the anterior surface of the common bile duct. An end-to-side duct-to-mucosa pancreaticojejunostomy was performed. The main pancreatic duct in the ventral segment on the dissection parenchymal surface was ligated. With the inclusion of this case, there are a total of 3 cases involving resection of the dorsal portion of the pancreatic head reported in the literature.

CONCLUSION

HDP seems to be technically feasible and safe for not enucleable benign or low-grade malignant neoplasms involving the dorsal pancreatic head. However, due to the singularity of the indications and the few cases reported in the literature, further studies are needed to validate the technique.

Spatial and temporal dynamics of innervation during the development of fetal human pancreas

The delineation of pancreatic nerve innervation during fetal life may contribute to our understanding of pancreatic pain modalities after birth. The aim of this study was to characterize the spatial and temporal distribution of nerve structures in the human pancreas throughout gestation. Computer-based image morphometry with piecewise polynomial interpolation analysis was performed to quantify nervous structures in the head, body and tail of the pancreas. Nerve structures were detected by automatic immunostaining techniques using a polyclonal antibody against two S-100 proteins that reacts strongly with human S100A and B that are detected in Schwann cells. Immunoreactivity was found in the parenchyma of head, body and tail of the pancreas with the relative density being head>body>tail. In addition to this extensive set of nerve fibers terminating in the pancreas there were large bundles of en passant nerve fibers in the dorsal region of the pancreas that were 3D reconstructed and were associated with the superior mesenteric plexus. If at first glance, the perimeter and the width of the nerve fibers seem to increase at a continuous rate up to term in all three regions of the pancreas, spatial and temporal co-analysis identified that the head of the pancreas shows a two-peak growth increase at 14 and 22 weeks of gestation with regard to the area, perimeter and width of the nerve structures, while the body and tail regions show a unique peak at 20 weeks. A developmental deceleration was found between the 22nd and the 36th week of gestation for the head region only. This is the first systematic study of nerve innervation of the human pancreas throughout gestation. The developmental dynamics of the pancreas nerve innervation corresponds approximately to the remodeling of the intrahepatic biliary system. Understanding the factors and disease states that may alter the distribution of nerve structures can be of significance for the development of therapies in pancreatic disorders of child- and adulthood.