Morphological predictors for lymph node metastases on computed tomography in colon cancer.

INTRODUCTION/BACKGROUND: The aim of the study was to assess morphological predictors for lymph node metastases (Stage III disease) in colon cancer on computed tomography. METHODS AND MATERIALS: Ninety-four patients with histology-proven colon cancer (adenocarcinoma) who underwent elective primary curative resection between the years 2012 and 2014 were included. Contrast-enhanced CT examinations were independently reviewed by two blinded observers regarding tumor location, depth of tumor invasion, and presence of lymph node metastases. Ocular presence of internal heterogeneity and presence of irregular outer border were used as morphological criteria for lymph node involvement. Protocol-based histopathology after curative surgery served as reference standard. Sensitivity, specificity, positive (PPV) and negative (NPV) predictive values, and accuracy for each morphological criterion for prediction of stage III disease were calculated. Inter-observer agreement was compared using Kappa statistics. RESULTS: According to histopathology, 59 patients were staged as I-II disease and 35 patients were staged as stage III disease. The presence of internal heterogeneity in a lymph node on CT resulted in moderate sensitivity (66-77%) but high specificity (95-95%) for prediction of Stage III disease by both observers. The presence of irregular outer border also resulted in poor sensitivity (49-54%) but high specificity (97-97%). The combination of either internal heterogeneity and/or irregular outer border per patient resulted in a moderate sensitivity (67-77%) and high specificity (95-95%), PPV (89-96%), and NPV (84-88%). Inter-observer agreement (Cohens Kappa) was 0.72. Consensus reading for the combined criteria resulted in sensitivity and specificity of 69% and 100%, respectively. CONCLUSION: Using morphological criteria for lymph node metastases on CT examination in patients with colon cancer results in high specificity but moderate sensitivity in predicting stage III disease.

Assessment and diagnostic accuracy of lymph node status to predict stage III colon cancer using computed tomography.

BACKGROUND: To study different imaging criteria for prediction of lymph node metastases (Stage III disease) in colon cancer using CT. METHODS: In a retrospective setting, 483 consecutive patients with histology proven colon cancer underwent elective primary resection during 2008-2011, a cohort of 119 patients were included. Contrast enhanced CT examinations, in portal-venous phase, were reviewed with assessment of the number of lymph nodes, their anatomical distribution, size, size ratio, internal heterogeneity, presence of irregular outer border and attenuation values. Sensitivity, specificity, PPV and NPV for each studied criteria for prediction of stage III disease was calculated. RESULTS: According to histopathology 80 patients were stage I-II and 39 were stage III. Of the studied CT-criteria for lymph node metastases per patient, internal heterogeneity in at least one lymph node resulted in the best performance with sensitivity, specificity, PPV and NPV of 79, 84, 70 and 89%, Odds ratio (OR) 20. Presence of irregular outer border resulted in a sensitivity, specificity, PPV and NPV of 59, 81, 61 and 82%, OR 6.2. If both internal heterogeneity and/or irregular outer border was used as a criterion this resulted in a sensitivity, specificity, PPV and NPV of 85, 75, 62 and 91%, OR 16.5. None of the size criteria used were predictive for stage III disease. CONCLUSIONS: When performing preoperative CT in patients with colon cancer, the imaging criteria that allow best prediction of stage III disease on CT are either presence of at least one lymph node with internal heterogeneity or internal heterogeneity and/or irregular outer border. These criteria have to be validated in a prospective study.

Potentials of high resolution magnetic resonance imaging versus computed tomography for preoperative local staging of colon cancer.

BACKGROUND: Preoperative identification of locally advanced colon cancer is of importance in order to properly plan treatment. PURPOSE: To study high resolution T2-weighted magnetic resonance imaging (MRI) versus computed tomography (CT) for preoperative staging of colon cancer with surgery and histopathology as reference standard. MATERIAL AND METHODS: Twenty-eight patients with a total of 29 tumors were included. Patients were examined on a 1.5 T MR unit using a phased array body coil. T2 turbo spin-echo high resolution sequences were obtained in a coronal, transverse, and perpendicular plane to the long axis of the colon at the site of the tumor. Contrast-enhanced CT was performed using a protocol for metastasis staging. The examinations were independently evaluated by two gastrointestinal radiologists using criteria adapted to imaging for prediction of T-stage, N-stage, and extramural venous invasion. Based on the T-stage, tumors were divided in to locally advanced (T3cd-T4) and not locally advanced (T1-T3ab). Surgical and histopathological findings served as reference standard. RESULTS: Using MRI, T-stage, N-stage, and extramural venous invasion were correctly predicted for each observer in 90% and 93%, 72% and 69%, and 82% and 78% of cases, respectively. With CT the corresponding results were 79% and 76%, 72% and 72%, 78% and 67%. For MRI inter-observer agreements (Kappa statistics) were 0.79, 0.10, and 0.76. For CT the corresponding results were 0.64, 0.66, and 0.22. CONCLUSION: Patients with locally advanced colon cancer, defined as tumor stage T3cd-T4, can be identified by both high resolution MRI and CT, even when CT is performed with a metastasis staging protocol. MRI may have an advantage, due to its high soft tissue discrimination, to identify certain prognostic factors such as T-stage and extramural venous invasion.

Polyp detection with MDCT: a phantom-based evaluation of the impact of dose and spatial resolution.

OBJECTIVE: The objective of our study was to evaluate the impact of dose and spatial resolution on the detection of colonic polyps using a 4-MDCT scanner. MATERIALS AND METHODS: Twenty-four latex phantoms that simulate the large bowel and contain artificial polyps of different sizes and shapes were constructed. The polyps were divided into three size groups (diameter, 0-2, 2-5, and 5-10 mm) and were classified into four shape groups: pedunculated; broad-based; ulcerated or depressed; and sessile or flat. The colon phantoms were submerged in a water tank and scanned on a 4-MDCT scanner using 12 protocols with various settings of slice thickness, pitch, and tube current. The images were independently evaluated by three radiologists using axial 2D multiplanar reconstruction images and a 3D surface-rendering technique (fly-through). RESULTS: At a constant dose (i.e., dose-length product [DLP]), the polyp detection rate increased with increasing axial spatial resolution. For the standard protocol (2.50-mm slice thickness, 1.5 pitch), the detection rate for all polyp sizes decreased from approximately 70% at 100 mA to 55% at 40 mA. Between a 60- and 100-mA tube current, the detection rate for the largest polyps (> 5 mm) was almost constant, close to 90%. CONCLUSION: The detection of polyps in the large bowel using a standard protocol can be improved without dose penalty by increasing the axial spatial resolution of the image acquisition and adjusting the tube current setting. If the analysis can be restricted to polyps larger than 5 mm, the dose can be substantially reduced without compromising the detection rate.