Predisposing factors for pancreatic adenocarcinoma: What is the role of imaging?

Three-dimensional analysis of human pancreatic cancer specimens by phase-contrast based X-ray tomography - the next dimension of diagnosis

BACKGROUND

The worldwide increase of pancreatic ductal adenocarcinoma (PDAC), which still has one of the lowest survival rates, requires novel imaging tools to improve early detection and to refine diagnosis. Therefore, the aim of this study was to assess the feasibility of propagation-based phase-contrast X-ray computed tomography of already paraffin-embedded and unlabeled human pancreatic tumor tissue to achieve a detailed three-dimensional (3D) view of the tumor sample in its entirety.

METHODS

Punch biopsies of areas of particular interest were taken from paraffin blocks after initial histological analysis of hematoxylin and eosin stained tumor sections. To cover the entire 3.5 mm diameter of the punch biopsy, nine individual tomograms with overlapping regions were acquired in a synchrotron parallel beam configuration and stitched together after data reconstruction. Due to the intrinsic contrast based on electron density differences of tissue components and a voxel size of 1.3 μm achieved PDAC and its precursors were clearly identified.

RESULTS

Characteristic tissue structures for PDAC and its precursors, such as dilated pancreatic ducts, altered ductal epithelium, diffuse immune cell infiltrations, increased occurrence of tumor stroma and perineural invasion were clearly identified. Certain structures of interest were visualized in three dimensions throughout the tissue punch. Pancreatic duct ectasia of different caliber and atypical shape as well as perineural infiltration could be contiguously traced by viewing serial tomographic slices and by applying semi-automatic segmentation. Histological validation of corresponding sections confirmed the former identified PDAC features.

CONCLUSION

In conclusion, virtual 3D histology via phase-contrast X-ray tomography visualizes diagnostically relevant tissue structures of PDAC in their entirety, preserving tissue integrity in label-free, paraffin embedded tissue biopsies. In the future, this will not only enable a more comprehensive diagnosis but also a possible identification of new 3D imaging tumor markers.

MDCT evaluation of pancreatic contour variations in head, neck, body and tail: surgical and radiological significance

OBJECTIVE

The purpose of the study was to investigate the incidence of pancreatic contour variations on multidetector CT (MDCT) for abdominal examinations.

METHODS

A retrospective analysis of 700 MDCT scans was performed in patients who underwent triple phase CT abdomen between October 2018 and January 2021. After excluding 176 patients, finally total of 524 patients were included in the study. For simplification, we classified the pancreatic contour variations as classified by Ross et al. and Omeri et al. Pancreatic head-neck variations was classified into Type I-anterior, Type II-posterior and Type III-horizontal variety. Pancreatic body-tail variation was divided into Type Ia-anterior projection; Ib-posterior projection and Type IIa-globular, IIb-lobulated, IIc-tapered, and IId-bifid pancreatic tail.

RESULTS

The most common type of variation in the head was Type II (n = 112, 21.3%) followed by Type III (n = 37, 7%) and Type I (n = 21, 4%). The most common type of variation in the body of pancreas was Type Ia (n = 33, 6.2%) followed by Type Ib (n = 13, 2.4%). In the tail region of pancreas, the most common variation was Type IIb (n = 21, 4%) followed by Type IIa (n = 19, 3.6%).

CONCLUSION

Pancreatic contour variations are not very uncommon in daily practice. Knowledge of these variations is important for surgeons, radiologists and avoids misjudgement of normal pancreatic tissue as tumor or lymph node especially on unenhanced or single phase MDCT.

Imaging and Screening of Pancreatic Cancer

Given the low disease prevalence of both exocrine and endocrine cancers in the general population, screening is not recommended. However, in as many as 25% of cases there is a precursor lesion or an identifiable genetic predisposition. For these patients at increased risk, screening with imaging is recommended. Multidetector computed tomography, MR imaging or magnetic resonance cholangiopancreatography, and endoscopic ultrasound examination can be used as screening modalities. Recent advances in dual energy CT and total body MR imaging have increased the suitability of these noninvasive modalities as first-line imaging screening options.