Differentiation of early gastric cancer with ulceration and resectable advanced gastric cancer using multiphasic dynamic multidetector CT.

OBJECTIVES: Early gastric cancer with ulceration (EGC-U) mimics advanced gastric cancer (AGC), as EGC-Us and ACGs often have similar endoscopic appearance to ulceration. The purpose of this retrospective study was to determine whether multiphasic dynamic multidetector CT (MDCT) can help differentiate EGC-Us from AGCs. METHODS: Patients with EGC-Us with ulcer stages Ul-III or IV and AGCs with tumour stages T2 to T4a were enrolled. MDCT images were obtained 40 s (arterial phase), 70 s (portal phase) and 240 s (delayed phase) after injection of non-ionic contrast material. Two readers independently measured the attenuation values of the lesions by placing regions of interest. We compared the EGC-Us and AGCs using the mean attenuation values in each phase and peak enhancement phase. We analysed the diagnostic performance of CT for differentiating EGC-Us from AGCs. RESULTS: Forty cases (16 EGC-Us and 24 AGCs) were analysed. The mean attenuation values of the EGC-Us were significantly lower than those of the AGCs in both the arterial and portal phases (all p < 0.0001 for each reader). The peak enhancement was significantly different between the EGC-Us and AGCs for both readers (Reader 1, p = 0.0131; Reader 2, p = 0.0006). CONCLUSION: Multiphasic dynamic contrast-enhanced MDCT can help differentiate EGC-Us from AGCs. KEY POINTS: • Early gastric cancer with ulceration and advanced gastric cancer have similar endoscopic appearances. • EGC-U shows significantly lower attenuation values in both arterial and portal phases. • Multiphasic dynamic contrast-enhanced MDCT differentiates EGC-U from AGC.

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.

Clinical significance of dual-energy dual-layer CT parameters in differentiating small-sized gastrointestinal stromal tumors from leiomyomas.

PURPOSE: Small gastrointestinal stromal tumors (GISTs) can generally have nonspecific CT findings similar to those with benign submucosal tumors of the stomach. The purpose of this study was to explore the potential dual-layer dual-energy CT (dlDECT) parameters to differentiate small-sized (≤ 4 cm) GISTs from leiomyomas of the stomach. MATERIALS AND METHODS: This retrospective study included 26 SMTs ≤ 4 cm in diameter with pathological confirmation of either GIST (n = 17) or leiomyoma (n = 9) from May 2018 to January 2022. All patients received contrast-enhanced CT. The normalized iodine concentration (NIC) and spectral slope (λHU) were compared between GIST and leiomyoma. Receiver-operating characteristic (ROC) curves were plotted and the areas under the curve (AUCs) were calculated to estimate the diagnostic performance of these markers for differentiating GISTs from leiomyomas. RESULTS: NIC was significantly higher in GIST than in leiomyoma in the portal (P = 0.0019) and delayed phases (P = 0.0011). λHU was significantly higher in GIST than in leiomyoma in the portal (P = 0.0006) and delayed phases (P = 0.0009). AUC of the ROC curves using NIC to differentiate between GIST and leiomyoma were 0.875 and 0.895 in the portal and delayed phase; using λHU, they were 0.918 and 0.902 in the portal and delayed phase. CONCLUSION: dlDECT parameters including NIC and λHU show promise as indicators for differentiating small-sized GISTs from leiomyomas.

Extracellular volume fraction determined by equilibrium contrast-enhanced computed tomography: correlation with histopathological findings in gastric cancer.

PURPOSE: To assess the relationship between histopathological features of gastric cancer and the extracellular volume fraction (ECV) measured by preoperative equilibrium contrast-enhanced computed tomography (CECT). MATERIALS AND METHODS: The study group consisted of 66 patients with surgically resected gastric adenocarcinoma who underwent preoperative multiphasic CECT. Tumor ECVs were calculated using region-of-interest measurements within the gastric cancer and aorta of each case on unenhanced and equilibrium-phase images. The relationship between the mean ECV values and clinicopathological parameters was examined by univariate analysis. Parameters showing a significant difference in the former test were further tested by linear regression and receiver operating characteristic (ROC) curve analyses. RESULTS: In the univariate analysis, the values of venous invasion (p = 0.0487) and tumor infiltration (INF) pattern (p < 0.0001) were significantly correlated with the tumor ECV. INF was significantly correlated (ß = 0.57, p < 0.0001) in the linear regression analysis. The tumor ECV showed better diagnostic accuracy for predicting INF (INFa/b vs INFc), and the area under the ROC curve value was 0.89. CONCLUSION: Tumor ECV determined by equilibrium CECT is significantly correlated with the pathological INF of gastric cancer.

A case of KIT negative extra-gastrointestinal stromal tumor arising in the greater omentum with predominant cystic formation.

We report a rare case of KIT-negative extra-gastrointestinal stromal tumor, in a 40-year-old woman. Contrast-enhanced computed tomography and magnetic resonance imaging revealed a >15-cm mass of multiple cystic lesions in the greater omentum. Histopathological findings after surgery showed a sheet-like growth of stellate tumor cells from epithelial cells, cystic degeneration, and mucus-like stroma. Immunohistochemistry was positive for discovered on GIST-1 (DOG1) but negative for CD117 (c-kit).

The Evolving Genomic Landscape of Esophageal Squamous Cell Carcinoma Under Chemoradiotherapy.

Esophageal squamous cell carcinoma (ESCC) often recurs after chemoradiotherapy, and the prognosis of ESCC after chemoradiotherapy has not improved over the past few decades. The mutation process in chemoradiotherapy-resistant clones and the functional relevance of genetic alterations remain unclear. To address these problems, we performed whole-exome sequencing of 52 tumor samples from 33 patients with ESCC who received radiotherapy combined with 5-fluorouracil/platinum. In multiregion analyses of pretreatment and locally recurrent lesions from five cases, most driver gene-altered clones remained under chemoradiotherapy selection pressure, while few driver gene alterations were acquired at recurrence. The mutation signatures of recurrent ESCC, including increased deletion frequency and platinum dose-dependent base substitution signatures, were substantially different from those of primary ESCC and reflected the iatrogenic impacts of chemoradiotherapy. Single-region analysis of 28 pretreatment tumors indicated that focal copy-number gain at the MYC locus was significantly associated with poor progression-free survival and overall survival after chemoradiotherapy. MYC gain remained throughout the chemoradiotherapy course and potentially contributes to intrinsic resistance to chemoradiotherapy. Consistent with these findings, MYC copy number and mRNA and protein levels in ESCC cell lines correlated positively with resistance to radiotherapy, and MYC knockdown improved sensitivity to radiotherapy. Overall, these data characterize the clonal evolution process induced by chemoradiotherapy and clinically relevant associations for genetic alterations in ESCC. These findings increase our understanding of therapeutic resistance and support the rationale for precision chemoradiotherapy. SIGNIFICANCE: Whole-exome sequencing reveals the genetic evolution of ESCC during chemoradiotherapy, highlighting MYC gain in pretreatment tumors as a potential marker of therapy resistance.

Factors of incomplete colonoscopy for stenosing colorectal cancer: CT colonography features.

PURPOSE: The purpose of this study was to examine the relation between computed tomography colonoscopy (CTC) features of colorectal cancer (CRC) and incomplete colonoscopy. MATERIALS AND METHODS: The subjects of this retrospective study consisted of 108 patients with advanced CRC (57 men, 51 women; age range, 32-87 years; median, 65 years) who underwent CTC. We compared local CTC features between the groups of complete (n = 74) and incomplete colonoscopy (n = 34). We performed a receiver operating characteristic (ROC) analysis to assess a diagnostic performance of CTC features to predict incomplete colonoscopy. RESULTS: The cross-sectional area of tumor and stenosis of complete colonoscopy group were significantly smaller and larger than those of incomplete colonoscopy group (p = 0.001 and < 0.001). Circumferential tumor extent rate (CER) showed significantly higher in the incomplete colonoscopy group than complete colonoscopy group (p < 0.001). In the ROC analysis, the cross-sectional area of stenosis showed AUC of 0.916, which was the best to predict incomplete colonoscopy. CONCLUSION: CTC features including larger cross-sectional area of tumor, smaller cross-sectional area of stenosis and 100% CER were significantly associated with incomplete colonoscopy for the patients with CRC.

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.

Diagnosis of early colorectal cancer invasion depth by quantitative evaluation of the basal indentation in CT colonography.

OBJECTIVE: To investigate the feasibility of diagnosing the invasion depth of early colorectal cancer (CRC) by quantitatively evaluating the basal indentation (BI)-i.e., the intestinal lateral deformity-in CT colonography (CTC). MATERIALS AND METHODS: 34 early CRCs (13 Tis CRCs and 21 T1 CRCs) in 32 patients who underwent a preoperative CTC were retrospectively examined. Two radiologists calculated the depth of the BI on a computed tomographic air-contrast enema (CT enema) image, the depth of the BI due to the geometric function (BI-G) on a cross-sectional multiplanar reconstruction (CS-MPR) image, and the ratio of the BI to the BI-G (i.e., the "BI ratio") for each lesion. The BI ratios of the Tis and T1 CRCs were compared. RESULTS: The BI ratios were significantly higher in the T1 CRCs than in the Tis CRCs (p < 0.0001). The optimum cutoff value of the BI ratio for differentiating the T1 CRCs from the Tis CRCs was 1.64, with a sensitivity, specificity, and area under the curve of 90.5 %, 100 %, and 0.974, respectively. CONCLUSIONS: We have demonstrated for the first time that quantitatively evaluating the BI can improve the accuracy of diagnosis of early CRC invasion depth.

A case of pelvic schwannoma presenting prominent eggshell-like calcification.

Pelvic schwannoma typically forms a large, well-circumscribed mass in the retroperitoneum or presacral area and frequently undergoes cystic degeneration. It appears as a well-demarcated round or oval mass, often showing prominent cystic degeneration and calcification. Characteristics of these calcifications are punctate, mottled, or curvilinear and are seen along the walls of the mass. Herein, we describe a case of schwannoma presenting a huge pelvic mass with unique eggshell-like calcification.

A case of rectal Dieulafoy's lesion successfully treated by transcatheter arterial embolization.

A 50-year-old man showed massive lower gastrointestinal bleeding without a triggering episode. An emergency colonoscopy revealed a protruding vessel in the lower rectum with no active bleeding. No underlying ulcer was seen within the surrounding mucosa. These findings were consistent with rectal Dieulafoy's lesion. Angiography was requested to identify the source of bleeding and for possible embolization. On the initial angiography, the bleeding point was unclear. Abnormal vessels such as arteriovenous malformation or nidus were not found. He again developed hematochezia, requiring transfusion of red blood cells. However, the second colonoscopy showed no active bleeding from the protruding vessel in the rectum. During the second angiography, sudden bleeding occurred. Angiography showed extravasation of contrast medium from the distal branch of the superior rectal artery. Transcatheter arterial embolization was performed, and was very effective.