C. Eveno

Proof of prometastatic niche induction by hepatic stellate cells

BACKGROUND An interaction between tumor cells and the microenvironment, as well as the development of angiogenesis, are required to form liver metastases (LMs). MATERIAL AND METHODS Immunofluorescence detection of α-smooth muscle actin, desmin, Ki67, laminin, and CD31 was used to analyze the kinetics of tumor angiogenesis determinants, especially the contribution of hepatic stellate cells (HSCs) to angiogenesis in hepatic metastasis produced by intrasplenically injected LS174 colorectal cancer cells. Immunostaining was performed at various times (days 9, 14, 28, and 39). RESULTS At the earliest stage, micrometastases consisted of proliferating cancer cells, a well-organized network of activated HSCs and laminin deposits. No vascular network was observed. As the LMs grew in size, an organized vascular network appeared; the laminin network colocalized with CD31 immunostaining. At the later stages, all the immunostained markers became peripheral as a central necrosis developed. Purified activated HSCs isolated from transgenic mice livers developing hepatocellular carcinoma secreted laminin and showed enhanced human umbilical vein EC network formation in a Matrigel assay. In a coinjection LM experiment, activated HSCs enhanced the metastatic process. Moreover, colorectal LMs from six patients were analyzed, and a pattern of marker distribution similar to the coinjection experiment was found in human LMs. CONCLUSIONS For the first time, our results show that HSCs play a crucial role in organizing and accelerating the progression of metastasis in modulating the prometastatic niche, interacting with colorectal cancer cell recruitment, and the organization of angiogenesis during colorectal LM development. Therefore, HSCs may be an early therapeutic target in colorectal cancer therapies.

Diffusion-weighted magnetic resonance imaging in colorectal cancer

Magnetic resonance imaging (MRI) plays now a major role in patients with colorectal cancer regarding tumor staging, surgical planning, therapeutic decision, assessment of tumor response to chemoradiotherapy and surveillance of rectal cancer, and detection and characterization of liver or peritoneal metastasis of colorectal cancers. Diffusion-weighted MRI (DW-MRI) is a functional imaging tool that is now part of the standard MRI protocol for the investigation of patients with colorectal cancer. DW-MRI reflects micro-displacements of water molecules in tissues and conveys high degrees of accuracy to discriminate between benign and malignant colorectal conditions. Thus, in addition to morphological imaging, DW-MRI has an important role to accurately detect colorectal neoplasms and peritoneal implants, to differentiate benign focal liver lesions from metastases and to detect tumor relapse within fibrotic changes. This review provides a comprehensive overview of basic principles, clinical applications and future trends of DW-MRI in colorectal cancers.

Acute colonic diverticulitis: an update on clinical classification and management with MDCT correlation

Currently, the most commonly used classification of acute colonic diverticulitis (ACD) is the modified Hinchey classification, which corresponds to a slightly more complex classification by comparison with the original description. This modified classification allows to categorize patients with ACD into four major categories (I, II, III, IV) and two additional subcategories (Ia and Ib), depending on the severity of the disease. Several studies have clearly demonstrated the impact of this classification for determining the best therapeutic approach and predicting perioperative complications for patients who need surgery. This review provides an update on the classification of ACD along with a special emphasis on the corresponding MDCT features of the different categories and subcategories. This modified Hinchey classification should be known by emergency physicians, radiologists, and surgeons in order to improve patient care and management because each category has a specific therapeutic approach.

Preoperative evaluation of small bowel complications in Crohn’s disease: comparison of diffusion-weighted and contrast-enhanced MR imaging

PurposeTo compare the accuracy of MR enterography (MRE) using combined T2-weighted and contrast-enhanced (CE) sequences with that of combined T2- and diffusion-weighted (DW) sequences for the detection of complex enteric Crohn’s disease (CD).MaterialsThirty-eight patients who underwent surgery for CD complications and preoperative MRE from 2011 to 2016 were included. MRE examinations were blindly analyzed independently by one junior and one senior abdominal radiologist for the presence of fistula, stenosis and abscesses. During a first reading session, T2-weighted images (WI), steady-state sequences and DW-MRE were reviewed (set 1). During a separate distant session, T2-WI, True-FISP and CE-MRE were reviewed (set 2). Performance of each reader was evaluated by comparison with the standard of reference established using intraoperative and pathological findings.ResultsForty-eight fistulas, 43 stenoses and 11 abscesses were found. For the senior radiologist, sensitivity for the detection of fistula, stenosis and abscess ranged from 80% to 100% for set 1 and 88% to 100% for set 2 and specificity ranged from 56% to 70% for set 1 and 53% to 93% for set 2, with no significant difference between the sets (p = 0.342–0.429). For the junior radiologist, sensitivity ranged from 53% to 63% for set 1 and 64% to 88% for set 2 and specificity ranged from 0% to 25% for set 1 and 17% to 40% for set 2 (p = 0.001 and 0.007, respectively).ConclusionFor a senior radiologist, DW-MRE has similar sensitivity as CE-MRE for the detection of CD complications. For a junior radiologist, CE-MRE yields the best results compared with DW-MRE.Key Points• For experienced readers, DWI has similar diagnostic capability as contrast-enhanced MR imaging for the diagnosis of Crohn’s disease complications.• For senior radiologists, gadolinium chelate injection could be waived for the diagnosis of Crohn’s disease complications.• The interpretation of DWI for Crohn’s disease complications requires some experience.

Preoperative detection of malignant liver tumors: Comparison of 3D-T2-weighted sequences with T2-weighted turbo spin-echo and single shot T2 at 1.5 T

PURPOSE To assess the performances of three-dimensional (3D)-T2-weighted sequences compared to standard T2-weighted turbo spin echo (T2-TSE), T2-half-Fourier acquisition single-shot turbo spin-echo (T2-HASTE), diffusion weighted imaging (DWI) and 3D-T1-weighted VIBE sequences in the preoperative detection of malignant liver tumors. METHODS From 2012 to 2015, all patients of our institution undergoing magnetic resonance imaging (MRI) examination for suspected malignant liver tumors were prospectively included. Patients had contrast-enhanced 3D-T1-weighted, DWI, 3D-T2-SPACE, T2-HASTE and T2-TSE sequences. Imaging findings were compared with those obtained at follow-up, surgery and histopathological analysis. Sensitivities for the detection of malignant liver tumors were compared for each sequence using McNemar test. A subgroup analysis was conducted for HCCs. Image artifacts were analyzed and compared using Wilcoxon paired signed rank-test. RESULTS Thirty-three patients were included: 13 patients had 40 hepatocellular carcinomas (HCC) and 20 had 54 liver metastases. 3D-T2-weighted sequences had a higher sensitivity than T2-weighted TSE sequences for the detection of malignant liver tumors (79.8% versus 68.1%; P < 0.001). The difference did not reach significance for HCC. T1-weighted VIBE and DWI had a higher sensitivity than T2-weighted sequences. 3D-T2-weighted-SPACE sequences showed significantly less artifacts than T2-weitghted TSE. CONCLUSION 3D-T2-weighted sequences show very promising performances for the detection of liver malignant tumors compared to T2-weighted TSE sequences.