CT colonography has advantages over colonoscopy for size measurement of colorectal polyps.

PURPOSE: The aim of this study was to compare the accuracy of colonoscopy (CS) and CT colonography (CTC) in the measurement of colorectal polyps using pathological size as a reference. MATERIALS AND METHODS: The analysis included 61 colorectal polyps in 28 patients who underwent preoperative CTC at our institution. All polyps were endoscopically resected. Polyp sizes were measured by CS and CTC. Endoscopic polyp size was extracted from endoscopy records written by one of two endoscopists (A with 11 and B with 6 years of endoscopic experience, respectively), who estimated the size visually/categorically without any measuring devices. After matching the location, the polyp size was measured on CTC using manual three-dimensional (3D) measurement on a workstation. The sizes of resected polyps were also measured after pathological inspection. Differences of the polyp size between CTC and histology, and between CS and histology were compared using paired t tests. Differences in measurement between the two endoscopists were also analyzed. RESULTS: The mean diameters of polyps measured using CS, CTC, and pathology were 10.5 mm, 9.2 mm, and 8.4 mm, respectively. There was a significant correlation between CS and pathology, as well as between CTC and pathology (both P < 0.0001). The correlation coefficient for CS (r = 0.86) was lower than that for CTC (r = 0.96). The correlations between CS and pathology for endoscopists A and B were 0.90 and 0.89, respectively. CONCLUSION: Measurements of polyp size using CTC were closer to the pathological measurements compared to those by CS, which exhibited greater variability. This suggests that CTC may be more suitable for polyp size measurements in the clinical setting if patients undergo CTC concurrently with colonoscopy.

CT gastrography "wall-carving technique" of gastric cancer: impact of contrast enhancement based on layer depth.

PURPOSE: Wall-carving technique (WC) is a special volume rendering technique of three-dimensional CT gastrography that can illustrate the enhancement of gastric wall at an arbitrary depth. We conducted the present study to evaluate the impact of contrast enhancement based on layer depth on WC of gastric cancer and to correlate them with pathological findings. METHODS: The subjects of this retrospective study consisted of 36 patients with advanced gastric cancer (22 men, 14 women; age range, 39-90 years; median, 67 years) who underwent contrast-enhanced CT before surgery. WC images of arterial phase were divided into first and second layer. Two radiologists in consensus evaluated the contrast enhancement of WC images for each layer and correlated with pathologic factors. RESULTS: Twenty-six (72%) of the gastric cancers showed a well-enhanced lesion in the first layer at the arterial phase on WC images, and 18 (50%) showed a well-enhanced lesion in the second layer. The study of second layers showed that the well-enhanced group had significantly more cases of differentiated type histology and intermediate stroma than the normally to poorly enhanced group (p = 0.008 and 0.0026). CONCLUSION: The contrast enhancement on WC of gastric cancer showed a significant relationship with pathological factors based on layer depth.

Gastric cancer with synchronous and metachronous hepatic metastasis predicted by enhancement pattern on multiphasic contrast-enhanced CT.

OBJECTIVE: The purpose of this study was to examine the relationship between the CT features of the primary-site gastric cancer and the concurrent existence or postoperative recurrence of hepatic metastasis. MATERIALS AND METHODS: From January 2013 to July 2016, 125 patients with advanced gastric cancer who were evaluated by gastroscopy and contrast-enhanced CT at our institution were included. Eleven patients had hepatic metastasis at the time of diagnosis (synchronous hepatic metastasis). Five patients had hepatic recurrence after surgery (metachronous hepatic metastasis, median follow-up period of 313 days), and another 56 patients had no hepatic recurrence during follow-up period (negative hepatic metastasis, median follow-up period of 1102 days). Two radiologists independently reviewed the CT images and they determined the peak enhancement phase, and then measured the CT attenuation value of the gastric lesion for each phase. We compared the parameters of synchronous, metachronous and negative hepatic-metastasis. We calculated diagnostic performance of CT for diagnosing synchronous and metachronous hepatic metastasis. RESULTS: The peak enhancement was significantly diff ;erent between the three groups for both readers (reader 1, p = 0.0001; reader 2, p = 0.0002). Most of the synchronous and metachronous hepatic metastasis had peak enhancement in the arterial or portal phase. The CT attenuation values of synchronous and metachronous hepatic metastasis were significantly higher than those of negative hepatic metastasis in the delayed phase according to both readers (reader 1, p = 0.0003; reader 2, p = 0.0002). In predicting synchronous hepatic metastasis using peak enhancement, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were 72.7%, 89.3%, 57.1%, 94.3%, and 86.6% for reader 1, and 54.5%, 94.6%, 66.7%, 91.4%, and 88.1% for reader 2. In predicting metachronous hepatic metastasis, the sensitivity, specificity, PPV, NPV, and accuracy were 60.0%, 89.3%, 33.0%, 94.3%, and 86.9% for reader 1, and 40.0%, 94.6%, 40.0%, 94.6%, and 90.2% for reader 2. CONCLUSION: Our study showed that gastric cancer with synchronous and metachronous hepatic metastasis tends to show early enhancement with a washout pattern on contrast-enhanced CT. This feature would be helpful in image surveillance for synchronous or metachronous hepatic metastasis of gastric cancer.

Histopathologic diversity of gastric cancers: Relationship between enhancement pattern on dynamic contrast-enhanced CT and histological type.

PURPOSE: To evaluate the diagnostic value of contrast-enhanced computed tomography gastrography (CE-CTG) to predict the histological type of gastric cancer. MATERIALS AND METHODS: We analyzed 47 consecutive patients with resectable advanced gastric cancer preoperatively evaluated by multiphasic dynamic contrast-enhanced CT. Two radiologists independently reviewed the CT images and they determined the peak enhancement phase, and then measured the CT attenuation value of the gastric lesion for each phase. The histological types of gastric cancers were assigned to three groups as differentiated-type, undifferentiated-type, and mixed-type. We compared the peak enhancement phase of the three types and compared the CT attenuation values in each phase. RESULTS: The peak enhancement was significantly different between the three types of gastric cancers for both readers (reader 1, p=0.001; reader 2, p=0.009); most of the undifferentiated types had peak enhancement in the delayed phase. The CT attenuation values of undifferentiated type were significantly higher than those of differentiated or mixed type in the delayed phase according to both readers (reader 1, p=0.002; reader 2, p=0.004). CONCLUSION: CE-CTG could provide helpful information in diagnosing the histological type of gastric cancers preoperatively.

Diffuse-type gastric cancer: specific enhancement pattern on multiphasic contrast-enhanced computed tomography.

PURPOSE: To evaluate the enhancement pattern of diffuse-type gastric cancers (DGCs) on multiphasic contrast-enhanced computed tomography gastrography (CECTG). METHODS AND MATERIALS: We studied 21 consecutive clinically diagnosed DGC patients who underwent CECTG. Gastric distension was obtained using effervescent granules. CT images were obtained 40 s (arterial phase) and 240 s (delayed phase) after injection of a nonionic contrast material. Two radiologists reviewed the CT images and analyzed layers and enhancement patterns. The readers evaluated the enhancement degree (mild, moderate, or marked) and calculated CT attenuation values by placing circular regions of interest (ROIs) within each layer of the lesion. The CT findings of 11 operated cases were correlated with pathological results. RESULTS: Most lesions were double-layered in the arterial phase, with a moderately enhanced inner layer and a mildly enhanced outer layer, and single-layered in the delayed phase. The mean attenuation value of the inner layer (146 ± 32.8 HU) was significantly higher than that of the outer layer (80.4 ± 15.5 HU) in the arterial phase (p = 0.0001). In the pathological analysis, wall stratification was preserved in nine cases and not preserved in two cases. CONCLUSION: Most DGCs showed a double-layered pattern in the arterial phase and a single-layered pattern with moderate enhancement in the delayed phase.