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Purpose To compare attenuation measurements and image quality of virtual unenhanced phase (VUP) images with those of conventional true unenhanced phase (TUP) images on spectral dual energy computed tomography (DECT) with dual layer detector on abdominal tissues and to assess potential reduction in radiation dose. Material and method A total of 295 patients (185 men, 110 women; mean age 61 ± 17.6 [SD] years [range: 17–95 years]) who had undergone abdominal or thoraco-abdominal CT with pre- and post-contrast imaging (portal phase) with spectral DECT with dual layer detector were retrospectively analyzed. VUP images based on portal-venous phase DECT acquisition were generated. Regions of interest were defined in abdominal tissues (liver, spleen, kidney, muscle and fat) by two independent readers. Inter-technique agreement (VUP images vs. TUP images) on attenuation measurements was assessed. Signal-to noise ratio (SNR) and image quality of TUP and VUP images were compared. The radiation dose delivered to patients was compared with the radiation dose of protocols without TUP images. Results A total of 9880 ROIs were drawn in the abdominal tissues. The difference in mean attenuation values between TUP and VUP images was less than 15 HU in 98.3% and less than 10 HU in 92.3% of all measurements. VUP images overestimated attenuation in fat comparatively to TUP images. Image quality was evaluated as good or excellent in 77% (37/48) of TUP images and 54% (26/48) of VUP images. Using VUP images instead of TUP images could decrease the radiation dose by 32%. Conclusion VUP images demonstrate good agreement with TUP images in different abdominals tissues and can be obtained with similar image quality as TUP. VUP images appear as an alternative to TUP images, resulting in reduction of radiation dose delivered to the patient.

Teaching Point: This case highlights the extrapulmonary lymphatic abnormalities that may be associated with pulmonary lymphangioleiomyomatosis.

Teaching point: Boerhaave syndrome is a very rare life-threatening surgical emergency, often misdiagnosed at the patient’s admittance.

Objectives: To describe the normal and pathological radiological appearance of the appendix in the adult patient using ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI). Furthermore, to review the utility of the aforementioned imaging modalities in different clinical contexts. Summary: The diagnosis of an inflamed appendix based on clinical evaluation, biological data and crosssectional imaging. US is the first line technique to consider and is the modality of choice for children, young and thin patients and women of childbearing age. An inconclusive ultrasound examination should lead to the realization of a CT. The appearance of the normal and pathological appendix needs to be clarified, in view of the modern technological developments of US as well as on the basis of the new CT methods (multidetector CT, with or without dual energy, low-dose acquisition). CT examinations can be performed with or without intravenous injection of contrast medium, accompanied by oral or rectal opacification, with variable diagnostic performance depending on the thickness of the sections and the possible use of reconstructions. MRI remains the second most important examination for young patients and pregnant women. In view of such technical progress, the plain films of the abdomen no longer have a role in everyday practice. Conclusion: A better knowledge of the US and cross-sectional appearance (CT-MRI) of the normal or inflamed appendix should allow the radiologist to contribute to an optimal management of this very frequent acute clinical situation. This approach reduces unnecessary radiation and negative appendectomies and optimizes the health care expenditures

Teaching point: Metastatic involvement has to be considered in the differential diagnosis for diffuse bladder wall thickening

OBJECTIVE: The right ventricle is often overlooked on chest and even cardiac MDCT studies. This article will review the normal anatomy of the right ventricle on MDCT and the signs of its functional alterations. CONCLUSION: MDCT signs of right ventricular dysfunction should be known and checked in relevant cases, such as pulmonary embolism in particular, and in any disease that affects both the structure and function of the lungs in general.

3599 Background: Pre-operative CRT followed by total mesorectal excision (TME) is nowadays the standard of care for patient with LARC (cT3-T4N0 or cTxN+). Currently, pathologic complete response occurs in +/- 15% after CRT. Colorectal cancer T-cell infiltration is a strong prognostic factor for survival after primary tumor resection. Our aim was to determine whether T-cell infiltration in PTB could be predictive of tumor response and relapse after CRT + TME. Methods: Between 1999 and 2012, patients with LARC who underwent CRT + TME and with available clinical follow-up and PTB (with sufficient tumor cells density) were identified at the Cliniques universitaires St-Luc. The density of CD3 (T cells) and CD8 (cytotoxic) was quantified on immunostained PTB slides and analyzed with a dedicated image analysis software on whole-slide imaging. Comparisons were made using the Wilcoxon-Mann-Whitney test. Cumulative disease-free survival (DFS) was performed using the Kaplan-Meier estimator and compared by log-rank tests. Cox regression we used for uni- and multi-variate analysis. P value of less than 0.05 was considered statistically significant. Results: 154 patients (sex ratio M/F 1.8; mean age 65 years-old; upper (20%), mid (29%) and low rectum (51%), synchronous metastases (11%)) were analyzed. High CD3 and CD8 PTB densities were significantly associated with a higher pathological response (Dworak 3-4) and lower ypTNM stage after CRT +TME (p < 0,05). Higher CD3 and CD8 PTB densities were associated with higher patient DFS (CD3: HR = 2,30 (CI95%:1,15-4,59) p = 0,02; CD8: HR = 1,95 (CI95%: 1,01-3,75) p = 0,04). These results were confirmed in uni and multivariate analysis. CD3 and CD8 PTB densities added to pathological response (ypTNM/Dworak) but also clinical response (ycTNM) after CRT + TME increases significantly the accuracy prediction of tumor relapse. Conclusions: Pretherapeutic T-cell infiltration of LARC is predictive of tumor response and relapse after CRT +TME. This biomarker could be helpful for patient treatment decision. It must be validated in larger patient cohorts.

3618Background: Pre-operative CRT followed by total mesorectal excision (TME) is nowadays the standard for LARC (cT3-T4N0 or cTxN+). TME could be avoided for patients with pathologic complete respo...

Inflammatory myofibroblastic tumor (IMT) is a rare tumor, classified by WHO of intermediate biological potential with tendency for local recurrence and small risk for distant metastasis. Histologically IMT is a mixture of inflamma- tory cells and myofibroblastic spindle cells proliferation. To our knowledge there is no MRI description of mesenteric IMT in the literature. We would like to emphasize the correlation between medical imaging and anatomical pathology based on our experience of a mesenteric IMT in a 28-year-old patient.

Background: We present a case of a 23-year-old man having drug addiction. He is managed by the department of hematology for an idiopathic medullar aplasia. Two months before his admission, he was treated with bone marrow transplantation. During follow-up, we noted a nonspecific recent cutaneous lesion. He was admitted for acute digestive symptoms including anorexia, nausea, vomiting and abdominal pain.

The giant ulcer of esophagus is a rare entity in the context of human immunodeficiency syndrome. In front of this type of ulceration the radiologist must to distinguish between two types of ulcers HIV, cytomegalovirus (CMV). The differential diagnosis is necessary for orientation of the therapy and is the result of association between radiological, endoscopic and pathological findings.

Department of Medical Imaging, Universite Catholique de Louvain, Cliniques Universitaires St-Luc Brussels, Belgium (Prof E E Coche MD), Department of Medicial Imaging, Universite catholique de Louvain, Cliniques Universitaires St-Luc, Brussels, Belgium (C A Dragean MD, L Duquesne MD, B Ghaye MD), Department of Pathology, Universite catholique de Louvain, Cliniques Universitaires St-Luc, Brussels, Belgium (I Theate MD)

This study assesses how the metastatic immune landscape is impacting the response to treatment and the outcome of colorectal cancer (CRC) patients.Complete curative resection of metastases (n = 441) was performed for two patient cohorts (n = 153). Immune densities were quantified in the center and invasive margin of all metastases. Immunoscore and T and B cell (TB) score were analyzed in relation to radiological and pathological responses and patient's disease-free (DFS) and overall survival (OS) using multivariable Cox proportional hazards models. All statistical tests were two-sided.The spatial distribution of immune cells within metastases was nonuniform. Patients, as well as metastases of the same patient, had variable immune infiltrates and response to therapy. A beneficial response was statistically significantly associated with increased immune densities. Among all metastases, Immunoscore (I) and TB score evaluated in the least immune-infiltrated metastases were the strongest predictors for DFS and OS (five-year follow-up, Immunoscore: I 3-4: DFS rate = 27.9%, 95% CI = 15.2 to 51.3; vs I 0-1-2: DFS rate = 12.3%, 95% CI = 4.9 to 30.6; HR = 0.45, 95% CI = 0.28 to 0.70, P = .02; I 3-4: OS rate = 64.6%, 95% CI = 46.6 to 89.6; vs I 0-1-2: OS rate = 32.5%, 95% CI = 17.2 to 61.4; HR = 0.32, 95% CI = 0.15 to 0.66, P = .001, C-index = 65.9%; five-year follow-up, TB score: TB 3-4: DFS rate = 25.7%, 95% CI = 14.2 to 46.6; vs TB 0-1-2: DFS rate = 5.0%, 95% CI = 0.8 to 32.4; HR = 0.36, 95% CI = 0.22 to 0.57, P.001; TB 3-4: OS rate = 63.7%, 95% CI = 46.4 to 87.5; vs TB 0-1-2: OS rate: 21.4%, 95% CI = 9.2 to 49.8; HR = 0.25, 95% CI = 0.12 to 0.51, P.001, C-index = 67.8%). High TB score and Immunoscore patients had a median survival of 70.5 months, while low patients survived only 25.1 to 38.3 months. Nonresponding patients with high-immune infiltrates had prolonged DFS (HR = 0.28, 95% CI = 0.15 to 0.52, P = .001) and OS (HR = 0.25, 95% CI = 0.1 to 0.62, P = .001). The immune parameters remained the only statistically significant prognostic factor associated with DFS and OS in multivariable analysis (P.001), while response to treatment was not.Response to treatment and prolonged survival of metastatic CRC patients were statistically significantly associated with high-immune densities quantified into the least immune-infiltrated metastasis.