Effect of adjusted positioning on gastric distention and fluid distribution during CT gastrography

Added Value of the Sliding Sign on Right Down Decubitus CT for Determining Adjacent Organ Invasion in Patients with Advanced Gastric Cancer

Purpose

To investigate the added value of right down decubitus (RDD) CT when determining adjacent organ invasion in cases of advanced gastric cancer (AGC).

Materials and Methods

A total of 728 patients with pathologically confirmed T4a (pT4a), surgically confirmed T4b (sT4b), or pathologically confirmed T4b (pT4b) AGCs who underwent dedicated stomach-protocol CT, including imaging of the left posterior oblique (LPO) and RDD positions, were included in this study. Two radiologists scored the T stage of AGCs using a 5-point scale on LPO CT with and without RDD CT at 2-week intervals and recorded the presence of "sliding sign" in the tumors and adjacent organs and compared its incidence of appearance.

Results

A total of 564 patients (77.4%) were diagnosed with pT4a, whereas 65 (8.9%) and 99 (13.6%) patients were diagnosed with pT4b and sT4b, respectively. When RDD CT was performed additionally, both reviewers deemed that the area under the curve (AUC) for differentiating T4b from T4a increased (p < 0.001). According to both reviewers, the AUC for differentiating T4b with pancreatic invasion from T4a increased in the subgroup analysis (p < 0.050). Interobserver agreement improved from fair to moderate (weighted kappa value, 0.296-0.444).

Conclusion

RDD CT provides additional value compared to LPO CT images alone for determining adjacent organ invasion in patients with AGC due to their increased AUC values and improved interobserver agreement.

Clinicopathological features and CT findings of papillary gastric adenocarcinoma

PURPOSE

This study aimed to analyze the clinicopathological and computed tomography (CT) findings of papillary gastric adenocarcinoma and to evaluate the feasibility of the multivariate model based on clinical information and CT findings for discriminating papillary gastric adenocarcinomas.

METHODS

This retrospective study included 22 patients with papillary gastric adenocarcinoma and 88 patients with tubular adenocarcinoma. The demographic data, tumor markers, histopathological information, CT morphological characteristics, and CT value-related parameters of all patients were collected and analyzed. The multivariate model based on regression analysis was performed to improve the diagnostic efficacy for discriminating papillary gastric adenocarcinomas preoperatively. The diagnostic performance of the established nomogram was evaluated by receiver operating characteristic curve analysis.

RESULTS

The distribution of age, carcinoembryonic antigen, differentiation degree, neural invasion, human epidermal growth factor receptor 2 overexpression, P53 mutation status, 4 CT morphological characteristics, and 10 CT valued-related parameters differed significantly between papillary gastric adenocarcinoma and tubular adenocarcinoma groups (all p < 0.05). The established multivariate model based on clinical information and CT findings for discriminating papillary gastric adenocarcinomas preoperatively achieved the area under the curve of 0.920.

CONCLUSION

There existed differences in clinicopathological features and CT findings between papillary gastric adenocarcinomas and tubular adenocarcinomas. The combination of demographic data, tumor markers, CT morphological characteristics, and CT value-related parameters could discriminate papillary gastric adenocarcinomas preoperatively with satisfactory diagnostic efficiency.

A rare case of perforated gastric duplication cyst associated with gastric diverticulum

A 50-year-old man presented to the emergency department with a 1-day history of severe epigastric pain, vomiting and fever. He had a background of alcohol excess and smoking. The patient was tachycardic and febrile with an elevated white blood cell count and C reactive protein. CT demonstrated extensive upper abdominal free fluid, without free air, with a large cystic lesion arising from the greater curvature of the stomach, and a second smaller cystic lesion arising from the posterior aspect of the gastric fundus. The patient was managed with nasogastric drainage, parenteral nutrition, intravenous antibiotics and proton pump inhibitors, and CT-guided abdominal drainage, with resolution of sepsis, and further outpatient care was transferred to our unit. Follow-up endoscopy demonstrated a diverticulum arising from the posterior aspect of the gastric fundus, with normal mucosa throughout the remaining stomach, while CT showed an additional cystic lesion arising from the greater curvature, with thickening of the adjacent gastric wall consistent with a gastric duplication cyst (GDC). Laparoscopy confirmed a small diverticulum at the fundus, and a large GDC anteriorly with associated omental adhesions consistent with prior perforation-two wedge resections were performed. Histology demonstrated no evidence of malignancy or ectopic mucosa. The patient recovered uneventfully and remained free from recurrent symptoms at 6 weeks postoperatively. GDC is a rare entity, which may be associated with ectopic mucosa, malignant transformation and upper gastrointestinal perforation. No previous report describes the coexistence of a GDC and gastric diverticulum. Herein we describe the investigation and management of this condition, and review the associated peer-reviewed literature.

Gastric poorly cohesive carcinoma: differentiation from tubular adenocarcinoma using nomograms based on CT findings in the 40 s late arterial phase

OBJECTIVES

To summarise the CT findings of gastric poorly cohesive carcinoma (PCC) in the 40 s late arterial phase and differentiate it from tubular adenocarcinoma (TAC) using an integrative nomogram.

METHODS

A total of 241 patients including 59 PCCs, 109 TACs, and 73 other type gastric cancers were enrolled. Thirteen CT morphological characteristics of each lesion in the late arterial phase were evaluated. In addition, CT value-related parameters were extracted from ROIs encompassing the area of greatest enhancement on four-phase CT images. Nomograms based on regression models were built to discriminate PCCs from TACs and from non-PCCs. ROC curve analysis was performed to assess the diagnostic efficiency.

RESULTS

Six morphological characteristics, 10 CT value-related parameters, and the enhanced curve types differed significantly among the above three groups in the primary cohort (all p < 0.05). The paired comparison revealed that 10 CT value-related parameters differed significantly between PCCs and TACs (all p < 0.05). The AUC of the nomogram based on the multivariate model for discriminating PCCs from TACs was 0.954, which was confirmed in the validation cohort (AUC = 0.895). The AUC of another nomogram for discriminating PCCs from non-PCCs was 0.938, which was confirmed in the validation cohort (AUC = 0.880).

CONCLUSIONS

In the 40 s late arterial phase, the morphological characteristics and CT value-related parameters were significantly different among PCCs, TACs, and other types. PCCs were prone to manifest mucosal line interruption, diffuse thickening, infiltrative growth, and slow-rising enhanced curve (Type A). Furthermore, multivariate models were useful in discriminating PCCs from TACs and other types.

KEY POINTS

• Multiple morphological characteristics and CT value-related parameters differed significantly between gastric PCCs and TACs in the 40 s late arterial phase. • The nomogram integrating morphological characteristics and CT value-related parameters in the 40 s late arterial phase had favourable performance in discriminating PCCs from TACs. • More useful information can be derived from 40 s late arterial phase CT images; thus, a more accurate evaluation can be made in clinical practice.

Defining the Position of the Right Wall of the Esophageal Hiatus to Identify the Circumferential Distribution of Small Lesions of the Lower Esophagus

BACKGROUND

The reliability of methods for identifying the circumferential position of small lower esophageal lesions is unknown. We prospectively investigated a new method that presents lesion positions as times on a clock face.

METHODS

Eighty-seven patients were consecutively examined by endoscopy. After observing the esophagus, an endoscope was inserted into the stomach and fixed, and the greater curvature folds at the upper gastric corpus were set as horizontal on the endoscope monitor display. The scope was retrogressed into the lower esophagus. At this point, the right wall at the hiatus is at the 3 o'clock position (R-line). The scope was then retrogressed from the gastric angle to the cardia along the center of the lesser curvature in the retroflexed view to obtain the LC-line (the center of the lesser curvature at the cardia). The LC-line in the esophageal hiatus in the frontal view was then identified, and the angle between the R- and LC-lines (R-LC) was measured.

RESULTS

After excluding 7 patients with hernias >2 cm and 3 with esophageal stenosis, data from 77 patients were analyzed. The R-LC angle ranged from -38° to +35°. The mean R-LC angle was -0.3°± 15.9°, and its 95% confidence interval was [-4.0°, 3.3°] within [-15°, + 15°]. When indicating lesion locations as times on a clock face, there was an error of ±30 min (±15°); therefore, R- and LC-lines were shown to be identical on an equivalence test.

CONCLUSIONS

This new method allows the circumferential position of small lower esophageal lesions to be reliably represented as a clock face.

The Diagnostic Utility of Prone Position Chest CT for the Evaluation of Esophageal Cancer

The aim of this study was to assess the potential of a prone chest CT for the evaluation of esophageal cancer, as compared with a routine supine chest CT. 69 patients (67±18 years old) with pathologically confirmed esophageal cancers underwent MDCT in the supine and prone positions. The supine CT was performed first, followed by the prone position. Localization and staging of individual esophageal lesions on both the prone and supine CTs were assessed by two thoracic radiologists, using a scoring system that consisted of three confidence scales, and the results were correlated with the endoscopic and surgical findings. The mean confidence score for the detection of esophageal cancer was higher in the prone position (2.58±0.74) than that in the supine position (2.42±0.83) with statistical significance (p=0.002). The mean confidence score for predicting local invasion in the selected patients (n=18) who underwent esophagectomy was also higher in the prone position (2.39±0.85) than that in the supine position (2.06±0.73) with statistical significance (p=0.01). In 10 of 11 cases that showed definitive determination for periesophageal infiltration or adjacent organ invasion on the prone CT (score 3), the corresponding findings were also observed in the post-operative evaluations. In conclusion, prone chest CT for evaluating esophageal cancer could have advantages in regards to the localization of esophageal cancer and predicting local invasion compared to that of routine supine CT and can improve the diagnostic accuracy of chest CTs.

CT differentiation of poorly-differentiated gastric neuroendocrine tumours from well-differentiated neuroendocrine tumours and gastric adenocarcinomas

PURPOSE

To evaluate the differential CT features of gastric poorly-differentiated neuroendocrine tumours (PD-NETs) from well-differentiated NETs (WD-NETs) and gastric adenocarcinomas (ADCs) and to suggest differential features of hepatic metastases from gastric NETs and ADCs.

MATERIALS AND METHODS

Our study population was comprised of 36 patients with gastric NETs (18 WD-NETs, 18 PD-NETs) and 38 patients with gastric ADCs who served as our control group. Multiple CT features were assessed to identify significant differential CT findings of PD-NETs from WD-NETs and ADCs. In addition, CT features of hepatic metastases including the metastasis-to-liver ratio were analyzed to differentiate metastatic NETs from ADCs.

RESULTS

The presence of metastatic lymph nodes was the sole differentiator of PD-NETs from WD-NETs (P = .001, odds ratio = 56.67), while the presence of intact overlying mucosa with mucosal tenting was the sole significant CT feature differentiating PD-NETs from ADCs (P = .047, odds ratio = 15.3) For hepatic metastases, metastases from NETs were more hyper-attenuated than those from ADCs.

CONCLUSION

The presence of metastatic LNs and intact overlying mucosa with mucosal tenting are useful CT discriminators of PD-NETs from WD-NETs and ADCs, respectively. In addition, a higher metastasis-to-liver ratio may help differentiate hepatic metastases of gastric NETs from those of gastric ADCs with high accuracy.

KEY POINTS

• Presence of metastatic LNs is a useful differentiator of PD-NETs from WD-NETs. • Intact overlying mucosa with mucosal tenting suggests PD-NETs more than gastric ADCs. • Metastatic LNs are larger in size and greater in necrotic volume in PD-NETs. • Hepatic metastases from gastric NETs are more hyper-attenuated than those from ADCs.

Three-dimensional fusion images combining CT gastrography and CT angiography for early gastric cancer: pilot experiences of preoperative simulation prior to totally laparoscopic gastrectomy

We herein report two cases of gastric cancer in which preoperative 3-D CT gastrography and CT angiography fusion images enabled totally laparoscopic gastrectomy. Case 1 involved a 60-year-old woman with a superficial depressed lesion on the greater curvature of the middle gastric body. Case 2 involved a 64-year-old woman with a superficial depressed lesion on the posterior wall of the upper gastric body. In both cases, 3-D fusion images were prepared from enhanced CT scans after the area near the lesions was clipped under preoperative gastroendoscopy. Based on the relative position between the clips and nearby vessels, a resection line was preoperatively determined in each case. Totally laparoscopic distal gastrectomy and totally laparoscopic proximal gastrectomy were performed in cases 1 and 2, respectively, with safe surgical margins. Three-dimensional fusion images can help in preoperative simulation of totally laparoscopic gastrectomy.

The role of three-dimensional multidetector CT gastrography in the preoperative imaging of stomach cancer: emphasis on detection and localization of the tumor

Multidetector CT (MDCT) gastrography has been regarded as a promising technique for the preoperative imaging of gastric cancer. It has the ability to produce various three-dimensional (3D) images. Because 3D reconstruction images are more effective and intuitive for recognizing abnormal changes in the gastric folds and subtle mucosal nodularity than two-dimensional images, 3D MDCT gastrography can enhance the detection rate of early gastric cancer, which, in turn, contributes to the improvement of the accuracy of preoperative tumor (T) staging. In addition, shaded surface display and tissue transition projection images provide a global view of the stomach, with the exact location of gastric cancer, which may replace the need for barium studies. In this article, we discuss technical factors in producing high-quality MDCT gastrographic images and present cases demonstrating the usefulness of MDCT gastrography for the detection and T staging of gastric cancer while emphasizing the significance of preoperative localization of gastric cancer in terms of surgical margin.

State-of-the-art preoperative staging of gastric cancer by MDCT and magnetic resonance imaging

Gastric cancer is one of the most common and fatal cancers. The importance of accurate staging for gastric cancer has become more critical due to the recent introduction of less invasive treatment options, such as endoscopic mucosal resection or laparoscopic surgery. The tumor-node-metastasis staging system is the generally accepted staging system for predicting the prognosis of patients with gastric cancer. Multidetector row computed tomography (MDCT) is a widely accepted imaging modality for the preoperative staging of gastric cancer that can simultaneously assess locoregional staging, including the gastric mass, regional lymph nodes, and distant metastasis. The diagnostic performance of MDCT for T- and N-staging has been improved by the technical development of isotropic imaging and 3D reformation. Although magnetic resonance imaging (MRI) was not previously used to evaluate gastric cancer due to the modality’s limitations, the development of high-speed sequences has made MRI a feasible tool for the staging of gastric cancer.

Differentiation of large (≥ 5 cm) gastrointestinal stromal tumors from benign subepithelial tumors in the stomach: radiologists' performance using CT

PURPOSE

To identify significant CT findings for the differentiation of large (≥ 5 cm) gastric gastrointestinal stromal tumors (GIST) from benign subepithelial tumors and to assess whether radiologists' performance in differentiation is improved with knowledge of significant CT criteria.

MATERIALS AND METHODS

One-hundred twenty patients with pathologically proven large (≥ 5 cm) GISTs (n=99), schwannomas (n=16), and leiomyomas (n=5) who underwent CT were enrolled. Two radiologists (A and B) retrospectively reviewed their CT images in consensus for the location, size, degree and pattern of enhancement, contour, growth pattern and the presence of calcification, necrosis, surface ulceration, or enlarged lymph nodes. CT findings considered significant for differentiation were determined using uni- and multivariate statistical analyses. Thereafter, two successive review sessions for the differentiation of GIST from non-GIST were independently performed by two other reviewers (C and D) with different expertise of 2 and 9 years using a 5-point confidence scale. At the first session, reviewers interpreted CT images without knowledge of significant CT findings. At the second session, the results of statistical analyses were provided to the reviewers. To assess improvement in radiologists' performance, a pairwise comparison of receiver operating curves (ROC) was performed.

RESULTS

Heterogeneous enhancement, presence of necrosis, absence of lymph nodes, and mean size of ≥ 6 cm were found to be significant for differentiating GIST from schwannoma (P<0.05). Non-cardial location, heterogeneous enhancement, and presence of necrosis were differential CT features of GIST from leiomyoma (P<0.05). Multivariate analyses indicated that absence of enlarged LNs was the only statistically significant variable for GIST differentiating from schwannoma. The area under the curve of both reviewers obtained using ROC significantly increased from 0.682 and 0.613 to 0.903 and 0.904, respectively, with information of the significant CT findings differentiating GISTs from non-GISTs (P<0.001).

CONCLUSION

Non-cardial location, heterogeneous enhancement, presence of necrosis, larger lesion size, and absence of lymphadenopathy are highly suggestive CT findings for large GISTs in differentiation from schwannomas or leiomyomas. Regardless of radiologists' expertise, diagnostic performance in differentiation can be significantly improved with knowledge of these CT findings.

Gastric cancer: imaging and staging with MDCT based on the 7th AJCC guidelines

Gastric cancer is a common deadly cancer worldwide. The tumor-node-metastasis (TNM) staging system is one of the most commonly used staging systems, and is accepted and maintained by the International Union against Cancer (UICC) and the American Joint Committee on Cancer (AJCC). The TNM system is well known to effectively predict the prognosis of gastric cancer patients. The latest revision of TNM staging was presented in the 7th edition of the AJCC in 2009. Multi-detector row CT (MDCT) is a powerful test for non-invasive evaluation and can assess metastatic and locoregional staging simultaneously. Current MDCT with isotropic imaging and 3D images has increased the accuracy of T and N staging in patients with gastric cancer. Multi-planar reformatted images permit the radiologist to select the optimal imaging plane to accurately evaluate tumor invasion depth of the gastric wall and perigastric infiltration to identify a fat plane between a tumor and adjacent organs, to avoid partial volume averaging effects, and to differentiate lymph nodes from small perigastric vessels. Thus, MDCT provides a useful all-in-one diagnostic method for the pre-operative evaluation of patients with known, or strongly suspected, gastric cancer according to the 7th AJCC TNM staging system.

Benign regional lymph nodes in gastric cancer on multidetector row CT

BACKGROUND

Benign regional lymph nodes (LNs) are sometimes enlarged in gastric cancer patients due to reactive or inflammatory changes. Frequently these enlarged LNs can mimic LN metastasis and lead to overstaging.

PURPOSE

To assess frequency of benign regional LNs in gastric cancer patients compared with that in a healthy population and to assess the frequency of benign regional LNs in gastric cancer according to T-staging.

MATERIAL AND METHODS

Between August 2005 and June 2009, 177 patients with surgically proven gastric cancer without LN metastasis (TanyN0M0) who had previously undergone preoperative multidetector row CT (MDCT) and 168 healthy patients who visited the healthcare center and underwent an abdominal MDCT were included in this retrospective study. An abdominal radiologist evaluated the distribution of regional LNs and measured the short diameter of LNs ≥6 mm, ≥8 mm, and ≥10 mm. The number of enlarged benign LNs was compared between the two groups, and the distribution of LN with regard to T-stage of gastric cancer was also evaluated.

RESULTS

At least one LN ≥6 mm, ≥8 mm, and ≥10 mm was detected in 64.4% (114/177), 22.0% (39/177), and 4.0% (7/177) of patients in the gastric cancer group, respectively, compared to 29.8% (50/168), 4.2% (7/168), and 0% of patients in the healthy group, respectively. The difference between the two groups was statistically significant (P <0.0001). The LN ≥8 mm was found in 14.9% (20/134) in early gastric cancer (T1), and 44.2% (19/43) in advanced cancer (T2 or higher); the difference was statistically significant (P = 0.0002). However, the frequency of LN ≥6 mm in mucosal cancer (T1a) and submucosal cancer (T2b) was not significantly different, regardless of its size.

CONCLUSION

Benign regional LNs ≥6 mm are more frequently detected in gastric cancer patients than in a healthy population and in advanced gastric cancer than in early cancer.

Three-dimensional MDCT for preoperative local staging of gastric cancer using gas and water distention methods: a retrospective cohort study

OBJECTIVE

The purpose of this article is to compare the T-staging accuracy and lesion detectability of MDCT with gas distention versus water distention according to the surgical and histopathologic findings, for the preoperative evaluation of gastric cancer.

MATERIALS AND METHODS

For a 3-month period, 113 consecutive patients (72 men and 41 women; age range, 23-85 years; mean age, 58 years) with 116 surgically confirmed gastric cancers from a single institution were included in our study. All patients had undergone preoperative MDCT with either effervescent granules taken orally (n = 55) or after having drunk 1,000 mL of tap water (n = 58) to create gastric distention. In addition to transverse images, multiplanar reformation images and 3D surface shaded display images were also obtained with gas distention CT, and multiplanar reformation images were obtained with water distention CT. The CT images were retrospectively reviewed by two abdominal radiologists separately with regard to T staging and lesion detectability. The accuracy values were compared between the two methods using Fisher's exact test.

RESULTS

The T-staging accuracy for gastric cancer did not differ significantly between gas distention and water distention CT scans, according to both radiologists (p > 0.05). Furthermore, the staging accuracy values for T1a cancers on gas distention CT scans for radiologists 1 and 2 were also comparable with those of water distention CT scans (91.1% vs 85% for radiologist 1 and 89.3% vs 85% for radiologist 2; p > 0.05). However, the tumor detection rate was significantly higher on gas distention CT scans using 2D and surface shaded display images for both radiologists (94.6% for radiologist 1 and 91.1% for radiologist 2), compared with the rates for water distention CT scans (78.3% and 73.3%) or gas distention CT scans using only 2D images (75.0% and 67.9%) (p < 0.05).

CONCLUSION

MDCT using the gas distention technique showed performance comparable to that of the water distention technique for the T staging of preoperative gastric cancer with better lesion detectability.

Diagnostic performance of 64-channel multidetector CT in the evaluation of gastric cancer: differentiation of mucosal cancer (T1a) from submucosal involvement (T1b and T2)

PURPOSE

To identify the computed tomographic (CT) findings in T1a and T1b cancers and to evaluate the diagnostic performance of multidetector CT with two-dimensional multiplanar reconstruction and three-dimensional CT gastrography for evaluating the preoperative staging of gastric cancer, with special emphasis on the differentiation between T1a and T1b cancers.

MATERIALS AND METHODS

The institutional review board approved this retrospective study. A total of 148 patients with gastric cancer (64 T1a, 36 T1b, and 48 T2) were included. To identify CT findings in T1a and T1b cancers, two radiologists in consensus interpreted the preoperative CT images of the 100 T1 cancers to determine the morphologic characteristics to be used as staging criteria on CT images. By using univariate and multiple logistic regression analyses, the diagnostic criteria to identify T1a and T1b cancers were developed. To evaluate the diagnostic performance of multidetector CT by using the criteria, two other blinded reviewers independently analyzed the CT images of all 148 patients to assess the T (classifying the depth of invasion as T1a, T1b, or T2) and N (classifying nodal involvement as absent or present) stage. CT staging was correlated with histopathologic results. Interobserver agreement was assessed by using weighted kappa statistics.

RESULTS

The detectability of T1b cancer was significantly higher than that of T1a cancer (P = .003). T1b cancer showed well-enhancing mucosal thickening more frequently than did T1a cancer (P = .002). By using the modified CT criteria, the overall accuracy values of T staging and N staging were 64.9% (96/148) and 79.1% (117/148) for reviewer 1 and 63.5% (94/148) and 83.8% (124/148) for reviewer 2, respectively. Weighted kappa values of T and N staging were 0.795 and 0.641, respectively.

CONCLUSION

On multidetector CT images, T1a cancer shows different imaging features than does T1b cancer regarding enhancing characteristics and detectability. Multidetector CT provides relatively valuable results of T and N staging, including differentiation between T1a, T1b, and T2 gastric cancers.

Radiologist performance in differentiating polypoid early from advanced gastric cancer using specific CT criteria: emphasis on dimpling sign

OBJECTIVE

The purpose of this study was to retrospectively determine whether there are specific CT features that can be used to differentiate polypoid early from advanced gastric cancer and to assess the performance of radiologists using specific CT findings for differentiation.

MATERIALS AND METHODS

A review of medical records yielded the cases of 46 patients, 27 with polypoid early gastric cancer and 19 with polypoid advanced gastric cancer, whose CT scans were available for review. Two radiologists retrospectively reviewed the CT images for the presence and depth of dimpling at the tumor base, the presence of vessel invagination at the dimpling site, thickening of the low-attenuating outer layer, perigastric infiltration, and transmural full-thickness enhancement of the lesion. Individual CT findings relevant as predictors were determined with univariate and multivariate analyses. Individual review of CT scans subsequently was performed by two other radiologists, who were blinded to tumor stage but aware of the results of univariate and multivariate analyses. Individual performance was evaluated with receiver operating characteristic analysis.

RESULTS

The presence of severe dimpling greater than 3.5 mm at the base of the tumor (odds ratio, 31.3) had the highest odds ratio for differentiating early from advanced gastric cancer, followed by vessel invagination (odds ratio, 12.3), the presence of dimpling (odds ratio, 9.8), perigastric infiltration (odds ratio, 5.2), and transmural full-thickness enhancement (odds ratio, 4.8). Multivariate analysis showed that the presence of dimpling greater than 3.5 mm was the only independent variable that differentiated polypoid advanced gastric cancer from polypoid early gastric cancer (p = 0.001). Subsequent differentiation of advanced from early gastric cancer with the described CT findings was very good, yielding areas under the receiver operating characteristic analysis curves of 0.827 and 0.811 for the two observers.

CONCLUSION

Greater than 3.5 mm dimpling and other ancillary CT findings are helpful in differentiating polypoid advanced gastric cancer from polypoid early gastric cancer and contribute to good individual accuracy for differentiation.

Usefulness of CT volumetry for primary gastric lesions in predicting pathologic response to neoadjuvant chemotherapy in advanced gastric cancer

BACKGROUND

To investigate the utility of CT volumetry for primary gastric lesions in the prediction of pathologic response to neoadjuvant chemotherapy in patients with resectable advanced gastric cancer (AGC).

MATERIALS AND METHODS

Thirty-three consecutive patients with resectable AGC stage >or=T2 and N1), who had been treated with neoadjuvant chemotherapy and radical gastric resection, were prospectively enrolled in this study. There were 30 men and 3 women with a mean age of 53.8 years. Contrast-enhanced CT was obtained after gastric distention with air before and after chemotherapy using a MDCT scanner. Pre- and post-chemotherapy thickness or short diameter and volume of the primary gastric tumor and largest lymph node (LN), were measured using a dedicated 3D software by two radiologists in consensus. PET/CT was also performed and the peak standardized uptake value (SUV) of primary gastric tumor and largest LN before and after chemotherapy was measured. The percentage diameter, volume, and SUV reduction rates for both the primary gastric tumor and the LN, were calculated and correlated with the histopathologic grades of regression using the Spearman correlation test. Differentiation between pathologic responders and nonresponders was assessed using receiver operating characteristic (ROC) analysis.

RESULTS

Among the three CT parameters which showed significant correlation with the histopathologic grades of regression, the correlation factor was highest in the percentage volume reduction rate of primary gastric tumor (rho = 0.484, P = 0.004) followed by percentage volume reduction of the index node (rho = 0.397, P = 0.022), and percentage diameter reduction of the index node (rho = 0.359, P = 0.04). However, the percentage thickness decrease rate (P = 0.208) and the percentage SUV reduction rate (P = 0.619) of primary gastric tumor were not significantly correlated with the histopathologic grades of regression. When the optimal cutoff value of the percentage volume reduction rate of primary gastric tumor was determined to be 35.6%, a sensitivity of 100% (16/16) and a specificity of 58.8% (10/17) were achieved.

CONCLUSION

CT volumetry for primary gastric tumor may be the most accurate tool in the prediction of pathologic response following neoadjuvant chemotherapy in patients with resectable AGC.

Positioning during CT gastrography in patients with gastric cancer: the effect on gastric distension and lesion conspicuity

OBJECTIVE

We wanted to prospectively evaluate the effect of various positions of the patient on gastric distension and lesion conspicuity during performance of CT gastrography (CTG).

MATERIALS AND METHODS

One hundred thirteen consecutive patients with gastric cancer underwent CTG in the 30 degrees left posterior oblique (LPO), supine, and prone positions. Two radiologists scored (a grade from 1-4) the degree of gastric distension and the lesion conspicuity according to the three scanning positions and the three gastric portions. Two- (2D) and three-dimensional (3D) images were used for analysis. Finally, these data were compared with the endoscopic findings and surgical results.

RESULTS

The mean scores of gastric distension and lesion conspicuity for the LPO and supine positions were higher than those for the prone position (p < 0.001) in the gastric middle and lower portions. However, there was no significant difference between the LPO and supine positions (p > or = 0.21). As for the gastric upper portion, the mean scores of gastric distension in the prone position were higher than those in the two other positions (p < 0.001). The prone position showed better lesion conspicuity than the two other positions for only one of two cases of gastric cancer in the upper portion of the stomach.

CONCLUSION

CTG performed in the LPO position or the supine position combined with CTG performed in the prone position is optimal for achieving good gastric distension and evaluating the lesion conspicuity of gastric cancer.

Diagnostic accuracy of T and N stages with endoscopy, stomach protocol CT, and endoscopic ultrasonography in early gastric cancer

BACKGROUND

Preoperative accurate diagnosis of the T and N stages in early gastric cancer (EGC) is important in determining the application of various limited treatments. The aim of this study is to analyze the accuracy of T and N staging of EGC with esophagogastroduodenoscopy (EGD), Stomach protocol CT (S-CT), and endoscopic ultrasonography (EUS), and the factors influencing the accuracy.

METHODS

Four hundred and thirty-four patients preoperatively diagnosed as EGC using EGD or S-CT and undergoing curative gastrectomy at Seoul National University Hospital in 2005 were included. The T and N stage reviewed by experienced personnel were compared with the surgical pathology.

RESULTS

The predictive values for EGC of EGD, S-CT, and EUS were 87.4%, 92.2%, and 94.1%, respectively. The predictive values for node negativity of S-CT, and EUS were 90.1% and 92.6%, respectively. The factors leading to underestimation of T stage with EGD were the upper third location, the size greater than 2 cm, and diffuse type of tumor. Those with S-CT were female sex, the upper third location and lesion size greater than 2 cm.

CONCLUSIONS

Before applying limited treatment for EGC, a surgeon should consider the risk factors of underestimation of T stage with EGD or S-CT.

[X-ray and CT presentation of advanced gastric carcinomas of different locations]

We presented the X-ray and CT findings characteristic for gastric cancers of different localizations (localized in different parts of the stomach). Particularly, esophagogastric junction (EGJ) carcinomas and antral carcinomas are singled out, as two localizations of gastric cancer that we usually meet in everyday clinical and radiological practice, and which have completely different radiological presentation. Advanced carcinomas of esophago-gastric junction, whose incidence is on the rise, usually affect the distal segment of the esophagus, cardia, and proximal part of the stomach, in different proportions. Siewert's, and the Japanese classification of these tumors are listed. Due to the involvement of the distal esophagus, scanning region, besides the abdomen, should be expanded to the chest. Advanced cancer of the antral part of the stomach is presented by the X-ray as a fungating, infiltrative, or combined form, often capturing the entire wall circumference. Possible infiltration of the left liver, the body and neck of the pancreas, colon and anterior abdominal wall should be estimated by CT.

Three-dimensional MDCT Gastrography Compared With Axial CT for the Detection of Early Gastric Cancer

OBJECTIVE

To assess the diagnostic performance of multidetector-row computed tomography (CT) 3-dimensional CT gastrography (3-D CTG) to detect early gastric cancer (EGC) compared with axial CT images alone.

METHODS

Contrast-enhanced multidetector-row CT scanning was performed on 39 patients with histopathologically proven EGC. By using volume-rendering technique, CTG images were created and interval reviews of both the axial images without and with 3-D CTG images were performed independently by 2 radiologists retrospectively. The stomach was divided into 4 segments (ie, the cardia or fundus, body, angle, and antrum). For 156 gastric segments, the radiologists determined the presence of the lesion using a 5-point confidence level. The radiologists' performance for the lesion detection was evaluated by means of receiver operating characteristic analysis. Interobserver agreement was also analyzed. The ability of CTG to reveal the extent and the morphological features of the lesions was also evaluated and compared with the results of conventional studies.

RESULTS

Histopathologically, 41 EGCs were identified in 39 patients: 1 lesion was located in the fundus, 16 in the body, 9 in the angle, and 15 in the antrum. When 3-D CTG images were used, the receiver operating characteristic curve (AZ) analysis revealed a significant improvement in the diagnostic performance of both reviewers (AZ using axial CT images only, 0.608 and 0.602 for reviewers 1 and 2, respectively; AZ using CTG images, 0.821 and 0.822 for reviewers 1 and 2, respectively) (P < 0.05). The 3-D CTG also improved the sensitivity from 27% to 73% for reviewer 1 and from 29% to 76% for reviewer 2 (P < 0.05), as compared with the sensitivity when using axial CT images only. In addition, almost perfect agreement was achieved for CTG (weighted kappa, 0.836), whereas there was only moderate agreement for the axial CT images (weighted kappa, 0.445). The CTG provided information similar to that obtained by barium study and endoscopy in 51.6% and 59.5%, respectively, of the cases.

CONCLUSIONS

The combined interpretation of axial and 3-D CTG was significantly better for detecting EGC, with a diagnostic confidence higher than that using axial CT imaging alone.

Clinical value of CT three-dimensional imaging in diagnosing gastrointestinal tract diseases

AIM: To discuss the clinical value of CT three-dimensional (3-D) imaging in diagnosing gastrointestinal tract diseases.

METHODS: Three-D imaging findings of 52 patients were retrospectively analyzed. Three-D imaging methods included shaded surface display (SSD), volume rendering (VR), virtual endoscopy (VE) and multiplanar reformatting (MPR). The diagnosis results of CT 3-D were evaluated by comparison with those of endoscopy and/or surgical finding.

RESULTS: Fifty-two patients with gastrointestinal tract diseases were diagnosed by CT 3-D imaging, of whom 50 cases were correctly diagnosed and 2 were misdiagnosed. There were 33 cases of gastric diseases (27 with carcinoma, 5 with peptic ulcer and 1 with leiomyoma) and 19 large intestinal diseases (10 with colon carcinoma, 2 with carcinoma of the rectum, 5 with colon polypus and 2 with tuberculosis of the ileocecal junction). Twenty-two cases with prominent lesions (9 with subsequent hollow lesions), 20 with stenosis of cavity (8 with concomitant prominent lesions) and 10 with hollow lesions (5 with concomitant prominent lesions) were shown in 3-D images. The minimal lesion shown was 1.0 cm × 0.8 cm × 0.5 cm.

CONCLUSION: CT 3-D imaging, a non-invasive examination without pain, can display clearly and directly the lesions of gastrointestinal tract with accurate location and high diagnosis accuracy. It is an important complementary technique to endoscopy.