Lymph-node metastases: efficacy for detection with helical CT in patients with gastric cancer

Surgical Outcomes for Cancer at the Gastroesophageal Junction

The aim of this study was to evaluate the clinicopathological characteristics and prognostic factors of cancer at the gastroesophageal junction (GEJ) whose center is situated at a site within 2 cm above and below the junction. This retrospective study included 90 patients with cancer at the GEJ, including 58 with adenocarcinoma (ADC) and 32 with squamous cell carcinoma (SCC). ADC tumors were larger in size than SCC tumors. ADC and SCC at the GEJ showed a similar distribution of the pattern of lymphatic spread. The rate of lower mediastinal lymph node metastasis was approximately 20 per cent, which is similar to the nodes along the celiac artery and the nodes along the common hepatic artery. The overall survival rates were similar between the groups. The presence of five or more lymph node metastases was an independent prognostic factor according to a multivariate analysis. When two or more lymph nodes larger than 10 mm were detected preoperatively, five or more lymph node metastases were proven by histology in most cases. The most frequent sites of recurrence of ADC and SCC were the peritoneum and lymph nodes, respectively. Aggressive additional treatment may be needed if two or more lymph nodes are seen on preoperative imaging.

Using the K-nearest neighbor algorithm for the classification of lymph node metastasis in gastric cancer

Accurate tumor, node, and metastasis (TNM) staging, especially N staging in gastric cancer or the metastasis on lymph node diagnosis, is a popular issue in clinical medical image analysis in which gemstone spectral imaging (GSI) can provide more information to doctors than conventional computed tomography (CT) does. In this paper, we apply machine learning methods on the GSI analysis of lymph node metastasis in gastric cancer. First, we use some feature selection or metric learning methods to reduce data dimension and feature space. We then employ the K-nearest neighbor classifier to distinguish lymph node metastasis from nonlymph node metastasis. The experiment involved 38 lymph node samples in gastric cancer, showing an overall accuracy of 96.33%. Compared with that of traditional diagnostic methods, such as helical CT (sensitivity 75.2% and specificity 41.8%) and multidetector computed tomography (82.09%), the diagnostic accuracy of lymph node metastasis is high. GSI-CT can then be the optimal choice for the preoperative diagnosis of patients with gastric cancer in the N staging.

FDG PET imaging in the staging and management of gastric cancer

Gastric cancer is a leading cause of cancer death worldwide. Complete resection offers the only chance for permanent control, and accurate staging and evaluation of treatment response are crucial for appropriate management. Positron Emission Tomography (PET) is increasingly used to complement anatomic imaging in cancer management. PET use in gastric cancer has been limited by 1) some gastric histologies are not PET avid, 2) spatial resolution limits the ability to distinguish between primary tumor and compartment I or II lymph nodes, and 3) the lack of a unified criteria in how to interpret PET for management decisions. New criteria have been proposed establishing response metrics in the utilization of PET. More study is needed to support these criteria in routine practice and establish the place of PET in the staging and management of gastric cancer.

Surgical approaches to gastric cancer

While the incidence of gastric cancer has declined substantially, it remains a major cause of morbidity and mortality. Surgical resection offers the best chance for curative treatment. Despite numerous studies, surgical controversies persist including endoscopic resection, extent of gastric resection, degree of lymphadenectomy, and laparoscopic resection. Balancing the benefits with the risks of surgical morbidity and mortality is essential. This review examines these controversies and provides insight into the surgical management of gastric cancer.

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.

Nodal counts on MDCT as a surrogate marker for surgical curability in gastric cancer

BACKGROUND

Thin-slice multidetector row computed tomography (MDCT) has emerged as a promising diagnostic modality in various cancers. This study was designed to evaluate the utility of metastatic nodal counts on MDCT as a surrogate maker for surgical curability in gastric cancer.

METHODS

Between 2005 and 2007, a total of 92 patients with gastric cancer underwent preoperative MDCT at a slice thickness of 1.0 mm at our hospital. All regional lymph nodes showing metastatic involvement were preoperatively counted.

RESULTS

Although the total counts of metastatic lymph nodes on MDCT were significantly smaller than those found by histopathology (P = 0.00001), there was a significant correlation between nodal counts on MDCT and histopathology by Spearman's analysis [P < 0.0001, pathologic counts = 1.63x (counts on MDCT) + 2.5]. Nodal counts on MDCT of ≥4 were analyzed as putative pathologic nodal counts of ≥8 by the equation, and pathologic metastatic nodal counts of ≥8 were most significantly correlated with noncurative resection (P < 0.0001). According to the logistic regression analysis, nodal counts on MDCT of ≥4 were a significant independent variable for noncurative resection (P = 0.0052, odds ratio 26.68). Nodal counts on MDCT of ≥4 could distinguish noncurative patients from curative patients with 94.4% sensitivity and 71.6% specificity.

CONCLUSIONS

Nodal counts on MDCT could be a reliable surrogate maker for surgical curability of gastric cancer. This marker might enable us to select prospective candidates for additional or alternative treatments in gastric cancer.

Can serum interleukin-2 receptor alpha predict lymph node metastasis in early gastric cancer?

Purpose

Although local resection like endoscopic mucosal resection for early gastric cancer is accepted as a treatment option, one of the most important drawbacks of such an approach is the inability to predictlymph node metastasis. The aim of this study was to evaluate the serum soluble receptor alpha for interleukin-2 (IL-2Rα) level as a predictor of lymph node metastasis in the patients with early gastric cancer.

Methods

Assessment of pre-operative serum IL-2Rα levels was performed on 86 patients with early gastric cancer treated by gastrectomies combined with D2 lymph node resections and 20 healthy controls at Samsung Medical Center. Data on patient age and gender, tumor size, depth of invasion, histologic differentiation, and endoscopic findings were reviewed post-operatively. The submucosal lesions were divided into three layers (sm1, sm2, and sm3) in accordance with the depth of invasion.

Results

Lymph node metastasis was observed in 16 patients (18.6%). Statistically, the serum IL-2Rα level was an important predictive factor of lymph node metastasis in undifferentiated gastric cancer, and the cut-off point for the predictive value of serum IL-2Rα level was 200 U/mL.

Conclusion

The serum IL-2Rα level might be a good predictor of lymph node metastasis in undifferentiated early gastric cancer.

Phase II trial of combined treatment consisting of preoperative S-1 plus cisplatin followed by gastrectomy and postoperative S-1 for stage IV gastric cancer

BACKGROUND

To improve the poor prognosis in patients with stage IV (StIV) gastric cancer (GC), we conducted a multicenter phase II study of preoperative S-1 plus cisplatin followed by gastrectomy and postoperative S-1 for StIV GC (the protocol is registered at the clinical trial site of the National Cancer Institute; KYUH-UHA-GC03-01, NCT00088816).

METHODS

Eligibility criteria included histologically proven StIVGC. Patients received S-1 (80 mg/m(2)/day, days 1-21) plus cisplatin (60 mg/m(2) on day 8) for 2 courses. After preoperative chemotherapy (CTx), radical gastrectomy was performed. Postoperative S-1 (80 mg/m(2)/day, days 1-14) was administered every 3 weeks for 1 year.

RESULTS

Fifty-one patients were enrolled and all patients were followed for more than 2 years. The 2-year overall survival and progression-free survival rates were 43.1% (95% confidence interval [CI] 29.4-56.1%) and 33.3% (95% CI 20.9-46.2%), respectively. Preoperative chemotherapy was accomplished in 44 patients (86.3%). These 44 patients underwent surgery and R0 resection was achieved in 26. The rate of R0 resection for GC with a single StIV factor (n = 24) was 79.2% and that for GC with multiple StIV factors (n = 27) was 25.9%. All patients with cancer cells in peritoneal washings (cytology [Cy] 1) alone (n = 12) became Cy0 after preoperative chemotherapy. Postoperative chemotherapy was completed in 11 patients, including 8 with Cy1 alone. No treatment-related death was recorded. Recurrences were observed in 14 patients after R0 resection. The most frequent recurrence site was the peritoneum. Patients who underwent R0 resection and those with Cy1 alone had a better survival.

CONCLUSIONS

This perioperative treatment was safe and feasible for StIVGC but failed to show a survival benefit. In patients with StIVGC with Cy1 alone this treatment resulted in a better prognosis.

F-18 FDG PET/CT contributes to more accurate detection of lymph nodal metastasis from actively proliferating esophageal squamous cell carcinoma

PURPOSE

Evaluating the status of disease progression is critical for planning a therapeutic strategy for esophageal cancer. In this regard, F-18 fluorodeoxyglucose-labeled positron emission tomography (PET) is one of the most useful diagnostic modalities. However, there is room to improve its diagnostic performance, such as distinguishing lymph nodal metastases from false positives. In this study, we examined the diagnostic accuracy of fluorodeoxyglucose PET accompanied by computed tomography imaging (PET/CT) to detect regional lymph nodal metastasis from esophageal squamous cell carcinoma (ESCC).

METHODS

A total of 102 patients diagnosed as ESCC were subjected to this study. These patients had a preoperative PET/CT examination to evaluate the existence of metastasis. The values of maximum standardized uptake value (SUVmax) in primary tumors and in metastasized lymph nodes were measured to analyze their relationship with various clinicopathologic characteristics including the status of tumor cell proliferation, which was assessed by immunohistochemistry for Ki-67.

RESULTS

The SUVmax of the primary tumor was positively correlated with tumor size and vessel invasion, and was positively related with the SUVmax of lymph nodal metastasis, especially in cases of poorly differentiated ESCC. The SUVmax of metastasized lymph nodes was higher in larger-sized metastasized lymph nodes, whereas the Ki-labeling index of lymph nodal metastasis was positively related with the SUVmax per unit area (SUVmax/mm). The diagnostic accuracy of PET/CT (87.3%) was higher than that of conventional CT scans (78.4%).

CONCLUSIONS

The improved diagnostic accuracy of PET/CT can be explained by its ability to detect actively progressive metastasis at an early phase regardless of size.

F18-fluorodeoxyglucose-positron emission tomography and computed tomography is not accurate in preoperative staging of gastric cancer

PURPOSE

To investigate the clinical benefits of F18-fluorodeoxyglucose-positron emission tomography and computed tomography ((18)F-FDG-PET/CT) over multi-detector row CT (MDCT) in preoperative staging of gastric cancer.

METHODS

FDG-PET/CT and MDCT were performed on 78 patients with gastric cancer pathologically diagnosed by endoscopy. The accuracy of radiologic staging retrospectively was compared to pathologic result after curative resection.

RESULTS

Primary tumors were detected in 51 (65.4%) patients with (18)F-FDG-PET/CT, and 47 (60.3%) patients with MDCT. Regarding detection of lymph node metastasis, the sensitivity of FDG-PET/CT was 51.5% with an accuracy of 71.8%, whereas those of MDCT were 69.7% and 69.2%, respectively. The sensitivity of (18)F-FDG-PET/CT for a primary tumor with signet ring cell carcinoma was lower than that of (18)F-FDG-PET/CT for a primary tumor with non-signet ring cell carcinoma (35.3% vs. 73.8%, P < 0.01).

CONCLUSION

Due to its low sensitivity, (18)F-FDG-PET/CT alone shows no definite clinical benefit for prediction of lymph node metastasis in preoperative staging of gastric cancer.

Predicting lymph node status in patients with early gastric carcinoma using double contrast-enhanced ultrasonography

INTRODUCTION

Double contrast-enhanced ultrasonography (DCUS) is a new method we used in predicting lymph node metastasis (LNM) in patients with early gastric cancer.

MATERIAL AND METHODS

Seventy-six patients with early gastric cancer diagnosed by gastroscope and confirmed by pathology after operation were examined using DCUS preoperatively. Group N1 included 15 patients with LNM and group N0 61 patients without LNM.

RESULTS

In group N1, 13 patients (87%) had marked hyperenhancement during early arterial phase using DCUS, and 2 patients (13%) were unmarked as hyperenhancement. In group N0, 24 patients (39%) had marked hyperenhancement during early arterial phase using DCUS, and 37 patients (61%) had unmarked hyperenhancement. The sensitivity and specificity of marked hyperenhancement in predicting LNM in patients with early gastric cancer was 86.7% and 60.7% respectively, and the Youden's index was 0.474. The κ value of this method was 0.89.

CONCLUSIONS

Double contrast-enhanced ultrasonography is a new valuable method to evaluate LNM at an early stage of gastric cancer and prognosis of early gastric cancer preoperatively.

Lymph node metastasis of gastric cancer

Despite a decrease in incidence in recent decades, gastric cancer is still one of the most common causes of cancer death worldwide [1]. In areas without screening for gastric cancer, it is diagnosed late and has a high frequency of nodal involvement [1]. Even in early gastric cancer (EGC), the incidence of lymph node (LN) metastasis exceeds 10%; it was reported to be 14.1% overall and was 4.8 to 23.6% depending on cancer depth [2]. It is important to evaluate LN status preoperatively for proper treatment strategy; however, sufficient results are not being obtained using various modalities. Surgery is the only effective intervention for cure or long-term survival. It is possible to cure local disease without distant metastasis by gastrectomy and LN dissection. However, there is no survival benefit from surgery for systemic disease with distant metastasis such as para-aortic lymph node metastasis [3]. Therefore, whether the disease is local or systemic is an important prognostic indicator for gastric cancer, and the debate continues over the importance of extended lymphadenectomy for gastric cancer. The concept of micro-metastasis has been described as a prognostic factor [4-9], and the biological mechanisms of LN metastasis are currently under study [10-12]. In this article, we review the status of LN metastasis including its molecular mechanisms and evaluate LN dissection for the treatment of gastric cancer.

Support vector machine model for diagnosis of lymph node metastasis in gastric cancer with multidetector computed tomography: a preliminary study

Background

Lymph node metastasis (LNM) of gastric cancer is an important prognostic factor regarding long-term survival. But several imaging techniques which are commonly used in stomach cannot satisfactorily assess the gastric cancer lymph node status. They can not achieve both high sensitivity and specificity. As a kind of machine-learning methods, Support Vector Machine has the potential to solve this complex issue.

Methods

The institutional review board approved this retrospective study. 175 consecutive patients with gastric cancer who underwent MDCT before surgery were included. We evaluated the tumor and lymph node indicators on CT images including serosal invasion, tumor classification, tumor maximum diameter, number of lymph nodes, maximum lymph node size and lymph nodes station, which reflected the biological behavior of gastric cancer. Univariate analysis was used to analyze the relationship between the six image indicators with LNM. A SVM model was built with these indicators above as input index. The output index was that lymph node metastasis of the patient was positive or negative. It was confirmed by the surgery and histopathology. A standard machine-learning technique called k-fold cross-validation (5-fold in our study) was used to train and test SVM models. We evaluated the diagnostic capability of the SVM models in lymph node metastasis with the receiver operating characteristic (ROC) curves. And the radiologist classified the lymph node metastasis of patients by using maximum lymph node size on CT images as criterion. We compared the areas under ROC curves (AUC) of the radiologist and SVM models.

Results

In 175 cases, the cases of lymph node metastasis were 134 and 41 cases were not. The six image indicators all had statistically significant differences between the LNM negative and positive groups. The means of the sensitivity, specificity and AUC of SVM models with 5-fold cross-validation were 88.5%, 78.5% and 0.876, respectively. While the diagnostic power of the radiologist classifying lymph node metastasis by maximum lymph node size were only 63.4%, 75.6% and 0.757. Each SVM model of the 5-fold cross-validation performed significantly better than the radiologist.

Conclusions

Based on biological behavior information of gastric cancer on MDCT images, SVM model can help diagnose the lymph node metastasis preoperatively.

Has the accuracy of preoperative diagnosis improved in cases of early-stage gastric cancer?

BACKGROUND

Adequate preoperative evaluation for gastric cancer staging is essential to develop an individualized treatment strategy involving surgery with reduced lymphadenectomy and laparoscopic gastrectomy.

METHODS

A total of 509 gastric cancer patients with clinical Stage IA or IB disease were divided into two groups: 304 patients were admitted in 2000 or earlier (Group A), and 205 patients were admitted in 2001, when multidetector computed tomography (MD-CT) was available, or later (Group B). We evaluated the accuracy of the preoperative diagnoses of tumor depth, lymph node involvement, and tumor stage.

RESULTS

With respect to tumor depth, 94.5 and 52.8% of patients were staged correctly in cT1 and cT2 patients, respectively. Among both cT1 and cT2 patients, the underestimated rates were lower in Group B than in Group A. For nodal metastasis, 83.2 and 30.0% of patients were staged correctly in cN0 and cN1 patients, respectively. Among the cN0 patients, 82.1 and 84.7% of Group A and Group B patients, respectively, were staged correctly. Among the cN1 patients, none of the patients in Group B was underestimated, while 9.7% of Group A patients were underestimated. There was a significant increase in the percentage of correctly staged patients and a decrease in the percentage of underestimated patients in Group B in comparison to Group A in both cStage IA and cStage IB patients.

CONCLUSIONS

Remarkable advances have been observed in the accuracy of preoperative staging in the early stage of gastric cancer. However, it is necessary to continue to develop accurate preoperative and intraoperative diagnostic systems.

The role of ¹⁸F-FDG PET/CT in the assessment of suspected recurrent gastric cancer after initial surgical resection: can the results of FDG PET/CT influence patients' treatment decision making?

PURPOSE

(18)F-fluorodeoxyglucose (FDG) PET/CT has been widely used for staging, re-staging and for monitoring therapy-induced changes and response to therapy in patients with various types of cancer, but its utilization for gastric cancer has been limited. The purpose of this study was to evaluate the clinical role of FDG PET/CT in the detection of gastric cancer recurrence as compared with diagnostic CT and to assess the impact of FDG PET/CT results on patients' treatment planning.

METHODS

Thirty-four patients with suspected recurrent gastric cancer, who had previously undergone curative gastrectomy and lymph node dissection, were retrospectively analysed. The diagnostic CT and FDG PET/CT imaging were performed for all patients as clinically indicated. The results of FDG PET/CT were compared with the findings of the diagnostic CT. The changes in the clinical management of patients according to the results of FDG PET/CT were also evaluated.

RESULTS

FDG PET/CT was performed in 19 patients (55.9%) due to the suspicion of distant metastasis at diagnostic CT. The remaining 15 patients were suspected to have local recurrence at diagnostic CT (n = 4) or gastroscopy (n = 1) and due to an increase in tumour markers or clinical manifestations (n = 10). The FDG PET/CT result was positive in 23 patients (67.6%) and negative in 11 patients (32.4%). In total, 24 (70.6%) of the 34 patients had documented recurrent disease by histopathology in 7 (29.1%) and by clinical follow-up in 17 (70.9%), while 11 patients had no evidence of recurrent disease. FDG PET/CT correctly confirmed recurrent disease in 23 of the patients with recurrence and it was classified as true-positive in these patients. However, FDG PET/CT was false-negative in one patient but recurrent disease was confirmed by histopathology. The overall sensitivity, specificity, accuracy, positive and negative predictive values of FDG PET/CT were significantly superior to those of diagnostic CT (95.8 vs 62.5%, 100 vs 10%, 97 vs 47%, 100 vs 62.5% and 90.9 vs 10%, respectively, p = 0.012) in the detection of recurrent gastric cancer after initial surgery. The FDG PET/CT results changed the patients' management in 18 (52.9%) cases by leading to the use of previously unplanned treatment procedures in 9 (50%) patients and the avoidance of previously planned therapeutic procedures in 9 (50%) patients.

CONCLUSION

FDG PET/CT is a superior post-therapy surveillance modality for the diagnosis of recurrent gastric cancer compared with diagnostic CT imaging after initial surgery. In addition, integrated FDG PET/CT was specifically helpful in optimizing the treatment plan and it might play an important role in treatment stratification in the future.

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.

Size of the largest lymph node visualized on multi-detector-row computed tomography (MDCT) is useful in predicting metastatic lymph node status of gastric cancer

This study was designed to investigate whether the size of the largest lymph node (long-axis diameter [LAD] and short-axis diameter [SAD]) visualized using multi-detector-row computed tomography (MDCT) was useful for predicting the metastatic lymph node (MLN) status of gastric cancer. A retrospective analysis of 305 gastric cancer patients who underwent pre-operative MDCT was performed, followed by a prospective study in 61 gastric cancer patients to determine the diagnostic effectiveness of LAD and SAD. In the retrospective study, the accuracy of LAD and SAD for predicting the MLN status of gastric cancer was 51.1% and 45.9%, respectively. In the prospective study, the accuracy of LAD and SAD measurement and the traditional MDCT method of counting MLNs was 52.5%, 49.2% and 57.4%, respectively; the differences were not significant. In conclusion, the size of the largest lymph node in terms of LAD and SAD visualized on MDCT was useful for predicting the MLN status of gastric cancer, with accuracy comparable to the traditional MDCT method of counting the total number of MLNs detected.

Perfusion changes in gastric adenocarcinoma: evaluation with 64-section MDCT

BACKGROUND

Perfusion CT has been applied in many clinical areas, but few studies have addressed gastric cancer. This study is to investigate the feasibility of first-pass perfusion CT with volume-based technique to assess microcirculation of gastric adenocarcinoma.

METHODS

Perfusion CT of gastric adenocarcinoma was performed with 64-section MDCT in 58 patients, which were subdivided into three subgroups according to the location of the tumor. Perfusion, peak enhancement, time to peak, and blood volume were computed in the tumor and in normal gastric wall. Mean values of perfusion parameters were compared between the tumor and normal stomach, between tumors with and without lymph node metastases, and between different stages.

RESULTS

Blood volume was significantly increased in gastric adenocarcinoma compared with normal stomach (19.75 +/- 14.74 vs. 13.59 +/- 11.46 mL/100 g, in total stomach, P = 0.004). A total of 10.55 mL/100 g of blood volume was employed as the cut-off value to discriminate the microcirculation of the tumor from that of the normal stomach. There were no significant differences of any perfusion parameters between the subgroups with and without lymph node metastases, or between early and advanced cancer.

CONCLUSIONS

The first-pass perfusion CT with whole tumor acquisition technique is a feasible technique for quantifying tumor vascularity and angiogenesis in gastric adenocarcinoma.

The value of PET/CT for preoperative staging of advanced gastric cancer: comparison with contrast-enhanced CT

AIM

To date, no data are available on the use of PET/CT for preoperative staging of gastric cancer. We attempted to evaluate the value of PET/CT for preoperative staging of advanced gastric cancer, and to compare the use of PET/CT with contrast-enhanced CT (CECT).

MATERIALS AND METHODS

We analyzed PET/CT of 78 patients with surgically proven advanced gastric cancer who had undergone preoperative CECT. Qualitative analysis was conducted by assessing the presence of primary tumors and metastases with PET/CT and CECT.

RESULTS

Among 71 patients who underwent a gastrectomy, 69 primary tumors (93%) were diagnosed by PET/CT, while 64 primary tumors (90%) were detected by CECT (p=0.55). For regional lymph node metastasis, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of PET/CT vs. CECT were 41% vs. 25% (p=0.00019), 100% vs. 92% (p=0.31), 100% vs. 98% (p=0.46), 26% vs. 42% (p=0.14), and 51% vs. 72% (p=0.00089), respectively.

CONCLUSION

Overall, PET/CT showed comparable diagnostic performance to CECT in diagnosing primary tumors and regional lymph node metastases, though PET/CT was inferior to CECT for the sensitivity and accuracy in diagnosing regional lymph node metastases. Nevertheless, PET/CT would be useful when CECT findings were equivocal due to its high positive predictability.

Role of computed tomography perfusion in the evaluation of pancreatic necrosis and pancreatitis after endoscopic ultrasound-guided ablation of the pancreas in a porcine model

OBJECTIVES

To evaluate the role of computed tomography (CT) perfusion in detection of pancreatic necrosis and pancreatitis after endoscopic ultrasound-guided ethanol ablation of porcine pancreas and to correlate the evaluation with histopathology.

METHODS

Under endoscopic ultrasound guidance, 0.9% saline (control) and ethanol at 60%, 80%, and 100% concentrations were injected into the pancreatic tails of 4 pigs. On day 4, dynamic perfusion CT of the pancreas was performed. Perfusion analysis and evaluation of enhancement characteristics were done and correlated with histopathology.

RESULTS

Ethanol injections at 80% and 100% concentrations resulted in focal necrosis surrounded by focal pancreatitis, whereas 60% ethanol injection caused severe focal pancreatitis with microscopic necrosis. The necrotic area revealed reduced blood flow, blood volume, permeability-surface area product, and increased mean transit time compared with pancreatitis and normal tissue (P < or = 0.001). In the control pig, no pancreatitis or necrosis was observed on perfusion images and histopathology.

CONCLUSIONS

Pancreatic necrosis and pancreatitis after ethanol injection reduced the tissue perfusion on CT in comparison to normal tissue, with the changes being more substantial in necrosis than pancreatitis. These findings have possible implications in the accurate detection of pancreatic necrosis in patients with severe pancreatitis.

Paraaortic lymph node metastasis in patients with intra-abdominal malignancies: CT vs PET

AIM: To compare the diagnostic accuracy of computed tomography (CT) and positron emission tomography (PET) for the preoperative detection of paraaortic lymph node (PAN) metastasis in patients with intra-abdominal malignancies.

METHODS: Sixty-six patients with intra-abdominal malignancies who underwent both CT and PET before lymphadenectomy were included in this study. Histopathologically, 13 patients had metastatic PAN, while 53 had non-metastatic PAN. The CT criteria for metastasis were: short diameter of > 8 mm, lobular or irregular shape, and/or combined ancillary findings, including necrosis, conglomeration, vessel encasement, and infiltration. The PET criterion was positive fluorodeoxyglucose (FDG) uptake. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of both modalities were compared with the pathologic findings, and the false positive and false negative cases with both CT and PET were analyzed.

RESULTS: The sensitivity, specificity, PPV, NPV, and accuracy of CT were 61.5%, 84.9%, 50%, 90% and 80.3%, respectively. For PET, the percentages were 46.2%, 100%, 100%, 88.3%, and 89.4%. Additionally, there were 8 false positive CT cases (8/53, 15.1%) and zero false positive PET cases. Of the 13 metastatic PANs, there were 5 false negative CT scans (38.5%) and 7 (53.9%) false negative PET scans.

CONCLUSION: For detecting PAN metastasis, CT is more sensitive than PET, while PET is more specific.

Determining gastric cancer resectability by dynamic MDCT

PURPOSE

Multi-detector row CT (MDCT) has been widely used to detect primary lesions and to evaluate TNM staging. In this study we evaluated the accuracy of dynamic MDCT in the preoperative determination of the resectability of gastric cancer.

METHODS

MDCT was used to image 350 cases of gastric cancer diagnosed by biopsy before surgery. MDCT findings regarding TNM staging and resectability were correlated with surgical and pathological findings.

RESULTS

The accuracy of MDCT for staging gastric cancer was high, especially for tumour stage T1 (94.3%), lymph node stage N2 (87.3%), and for predicting distant metastases (>96.6%). When resectability was considered to be the outcome, the total accuracy of MDCT was 87.4%, sensitivity was 89.7% and specificity was 76.7%. Results showed high sensitivity for identifying peritoneal seeding (90.0%) and for predicting liver metastasis (80.0%).

CONCLUSION

Dynamic enhanced MDCT is useful for TNM staging of gastric cancers and for predicting tumour respectability preoperatively.

Gastric Adenocarcinoma: Is Computed Tomography (CT) Useful in Preoperative Staging?

BACKGROUND AND PURPOSE

Although multiple studies testing the accuracy of CT in the preoperative staging of gastric adenocarcinoma have been carried out, their results are controversial. Whilst some authors claim that CT is an accurate method for preoperatively staging gastric cancer, others have advocated the contrary. Because of this discrepancy we have retrospectively reviewed preoperative CT findings compared with histopathological results in patients with gastric adenocarcinoma.

PATIENTS AND METHODS

Seventy-two patients diagnosed with gastric cancer who underwent potentially curative surgery and preoperative staging CT of quality were included in the study. The size, gastric wall thickening, presence of lymphadenopathy, adjacent organ invasion and location of the gastric mass was recorded. Early tumors (T1 and T2) and more advanced tumors (T3 and T4) were grouped together. CT staging was correlated with the final histopathological stage (TNM). The global results were expressed as sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV).

RESULTS

Seventy-two cases were included with fifty-five being male and a median age of 67 years (range 33-91). CT correctly identified the location of the tumor in 56 (53% antropyloric, 18% subcardial). Median time from CT scan to surgery was fourteen days (range 2-49). In T detection: T1/T2 and T3/T4 with sensitivity of 70% and 61%. Lymph node involvement: Sensitivity 49%. Overstaged in 47% Understaged in 75%. Specificity of 53%. Nine patients with colon-mesocolon (5 patients) and pancreas (4 patients) invasion. Sensitivity 44% and specificity 96%.

CONCLUSION

Spiral CT is not an accurate method in predicting preoperative stages in gastric cancer.

Helical CT evaluation of the preoperative staging of gastric cancer in the remnant stomach

OBJECTIVE

The objective of our study was to evaluate the diagnostic performance of helical CT for evaluating the preoperative staging of gastric cancer in the remnant stomach.

MATERIALS AND METHODS

Preoperative helical CT images of 67 patients with gastric cancer in the remnant stomach were independently analyzed regarding staging of the tumor by two radiologists who were blinded to histopathologic and surgical results. The differences in their assessments were resolved by consensus including the opinion of a third radiologist. The radiologists were asked to determine the depth of tumor invasion of the gastric wall (T stage), classifying it as </= T2, T3, or T4; local lymph node involvement (N stage); and solid organ metastasis or peritoneal involvement (M stage). TNM staging on CT was correlated with the histopathologic results of the resected specimen or with the surgical findings. Interobserver agreement was assessed using weighted kappa statistics.

RESULTS

The overall accuracy of T staging for reviewers 1 and 2 and for the consensus reading were 83.6%, 78.2%, and 85.4%, respectively. Five of 34 </= T2 lesions were misdiagnosed as T3. The cause of the overstaging was the misconception of the postoperative fibrotic change of the anastomotic site as perigastric tumoral infiltration. Three of 18 T4 lesions were understaged because of inadequate gastric distention (n = 1) and misinterpretation of adjacent organ involvement as partial volume averaging (n = 2). The accuracy of N staging and M staging were 81.8% and 94.0% for reviewer 1; 78.2% and 91.0% for reviewer 2; and 81.8% and 94.0% for the consensus reading, respectively. The weighted kappa values of T staging, N staging, and M staging were 0.676, 0.619, and 0.924, respectively.

CONCLUSION

Contrast-enhanced helical CT can be used successfully to preoperatively evaluate the staging of remnant stomach cancer in patients who have undergone previous gastric resection.

Gastric cancer staging at isotropic MDCT including coronal and sagittal MPR images: endoscopically diagnosed early vs. advanced gastric cancer

BACKGROUND

The aims of this study are to evaluate and compare the accuracies of isotropic multi-detector row CT (MDCT) including multiplanar reconstruction (MPR) images for preoperative staging of endoscopically diagnosed early gastric cancer (eEGC) and advanced gastric cancer (eAGC).

METHODS

One hundred and five patients with endoscopically proven gastric cancer underwent isotropic MDCT. Three independent radiologists evaluated T and N staging both on transverse images only and on three orthogonal MPR images. The staging of each tumor was surgico-pathologically confirmed. The receiver operating characteristic (ROC) analysis and the Wilcoxon signed ranked test were used for statistical analyses.

RESULTS

In 30 eAGCs, the accuracies for T and N staging with MPR imaging were better than those with transverse imaging (each P < 0.05). In 34 eEGCs, however, only the accuracy of T2 or higher with MPR imaging was higher than that with transverse imaging (P < 0.05).

CONCLUSIONS

Isotropic MDCT with MPR images including coronal or sagittal reconstructions can improve the accuracies of preoperative T and N staging of eAGC, while having little impact on the accuracy for eEGC.

Evaluation of lymph nodes with RECIST 1.1

Lymph nodes are common sites of metastatic disease in many solid tumours. Unlike most metastases, lymph nodes are normal anatomic structures and as such, normal lymph nodes will have a measurable size. Additionally, the imaging literature recommends that lymph nodes be measured in the short axis, since the short axis measurement is a more reproducible measurement and predictive of malignancy. Therefore, the RECIST committee recommends that lymph nodes be measured in their short axis and proposes measurement values and rules for categorising lymph nodes as normal or pathologic; either target or non-target lesions. Data for the RECIST warehouse are presented to demonstrate the potential change in response assessment following these rules. These standardised lymph node guidelines are designed to be easy to implement, focus target lesion measurements on lesions that are likely to be metastatic and prevent false progressions due to minimal change in size.

High DcR3 expression predicts stage pN2-3 in gastric cancer

BACKGROUND

A soluble decoy receptor 3 (DcR3), also known as TR6 or M68, is a member of the TNF receptor family. It has been reported that high DcR3 expression occurs in many tumors.

METHODS

This prospective study evaluated the DcR3 tissue status by RT-PCR and its correlation with the lymph node (N) stages in 62 primary gastric cancers.

RESULTS

DcR3 expression levels in patients with pN2-3 disease were much higher than those in patients with pN0-1 disease (median values 1.31 vs. 0, P < 0.01). Using ROC analysis, a cutoff level of DcR3 expression at 1.20 was found to be associated with optimal sensitivity and specificity of 62.5% (15 of 24) and 92.1% (35 of 38) respectively, in the prediction of stage pN2-3. According to the cutoff value, patients were divided into 2 groups with relatively high and low levels of DcR3 expression. Among the 18 patients with high DcR3 expression, 83.3% (15 of 18) were staged as pN2-3. In the other 44 patients with low DcR3 expression, only 20.5% (9 of 44) were identified as pN2-3. Logistic regression analysis for stage pN2-3 revealed that high DcR3 expression was an independent risk factor.

CONCLUSION

Gastric cancer patients with high DcR3 expression presented more advanced pN2-3 disease than those with low DcR3 expression. Preoperative checking DcR3 expression might be an additional approach to imaging modalities for evaluating N stages in gastric cancer to guide the operative procedures.

The role of surgery in the treatment of recurrent gastric cancer

BACKGROUND

The purpose of the current study was to determine the role of surgery in the treatment of recurrent gastric cancer.

METHODS

Of the 347 patients with recurrent gastric cancer, 61 patients (17.8%) who underwent surgery were evaluated retrospectively. The underlying causes and types of surgery, survival, and postoperative quality of life were analyzed.

RESULTS

The most common cause of surgery was intestinal obstruction due to carcinomatosis. Complete resection was possible in 15 patients (24.6 %), including 10 gastric remnant recurrences, and 2 hepatic and 3 ovarian metastases. The survival of patients who had complete resection was significantly longer than the other groups (52.2 months for complete resections, 13.1 months for palliative procedures, and 8.7 months for laparotomy alone, respectively) (P < .05). The median hospital-free survival (HFS) durations were 9.4, 2.9, and 2.2 months for incomplete resection, bypass/enterostomy, and laparotomy only, respectively (P < .05).

CONCLUSION

Surgical treatment in recurrent gastric cancer is rarely indicated; however, if complete resection could be accomplished, long-term survival can be expected. Bypass surgery for symptom palliation did not increase the HFS.

Hepatoid adenocarcinoma: computed tomographic imaging findings with histopathologic correlation in 6 cases

OBJECTIVE

Hepatoid adenocarcinoma (HAC) is a special type of primary tumor with aberrant hepatocellular differentiation occurring in extrahepatic organs. Our objective was to review the computed tomographic findings of HAC and to correlate the imaging features with histopathologic findings. Institutional review board approval was obtained for this study.

METHODS

The computed tomographic findings images in 6 consecutive patients with pathologically proven HAC were reviewed retrospectively. Five patients were men and 1 was a woman (mean age, 56 years; age range, 36-68 years). All patients underwent contrast-enhanced computed tomography (CT) performed on a 4-slice multidetector row CT scanner. The mean time interval between CT and surgery was 5 days. Two radiologists who were unaware of the final histological diagnosis reviewed all computed tomographic images retrospectively. Lesion characteristic (ie, number, location, size, density, enhancement, heterogeneity, margin, distribution, presence of necrosis, lymphadenopathy, and distant metastasis) were evaluated. The correlation between the imaging and the pathological findings was analyzed.

RESULTS

Most patients had elevated serum alpha-fetoprotein levels (n = 4). The HAC appeared as large tumors (mean size, 4.2 x 3.4 x 3.9 cm), isodense at unenhanced CT (n = 4), moderately enhanced (n= 5), with necrotic areas (n = 6), regional lymphadenopathy (n = 5), and distant metastases (n = 4). The heterogeneity on computed tomographic images correlated well with the presence of hemorrhage and necrosis.

CONCLUSIONS

In an old patient with a large necrotic and moderately vascular tumor, the presence of distant metastases, regional lymphadenopathy, and characteristic increased serum alpha-fetoprotein level may suggest a diagnosis of HAC.

Cross-sectional imaging of nodal metastases in the abdomen and pelvis

Accurate nodal staging is important for the management of patients with abdominal and pelvic malignancies. Local and nodal staging using cross-sectional imaging can influence treatment planning. The measurement of nodal size is still the most widely used criteria for discriminating between benign and malignant nodes. However, knowledge of the pathways of nodal spread, the treatment history, and careful analysis of nodal characteristics can improve nodal assessment. An appreciation of normal structures that may simulate nodal disease is also important. The potential for further improving nodal staging accuracy by positron emission tomography and magnetic resonance lymphography is discussed.

Hepatic entropy and uniformity: additional parameters that can potentially increase the effectiveness of contrast enhancement during abdominal CT

AIM

To determine how hepatic entropy and uniformity of computed tomography (CT) images of the liver change after the administration of contrast material and to assess whether these additional parameters are more sensitive to tumour-related changes in the liver than measurements of hepatic attenuation or perfusion.

MATERIALS AND METHODS

Hepatic attenuation, entropy, uniformity, and perfusion were measured using multi-phase CT following resection of colorectal cancer. Based on conventional CT and fluorodeoxyglucose positron emission tomography, 12 patients were classified as having no evidence of malignancy, eight with extra-hepatic tumours only, and eight with metastatic liver disease.

RESULTS

Hepatic attenuation and entropy increased after CM administration whereas uniformity decreased. Unlike hepatic attenuation, entropy and uniformity changed maximally in the arterial phase. No significant differences in hepatic perfusion or attenuation were found between patient groups, whereas arterial-phase entropy was lower (p=0.034) and arterial-phase uniformity was higher (p=0.034) in apparently disease-free areas of liver in patients with hepatic metastases compared with those with no metastases.

CONCLUSION

Temporal changes in hepatic entropy and uniformity differ from those for hepatic attenuation. By reflecting the distribution of hepatic enhancement, these additional parameters are more sensitive to tumour-related changes in the liver than measurements of hepatic attenuation or perfusion.

Value of multi-slice computed tomography in preoperative "one-station-style" examination for colon cancer

AIM: To assess the value of three-phase contrasted multi-slice computed tomography (MSCT) pneumocolon in preoperative examina-tion of colon cancer.

METHODS: Sixty-three patients with colonic cancer underwent plain MSCT pneumocolon and multiphase contrasted MSCT within 1 week before operation. Contrasted MSCT scans were performed using 16-slices CT system (Toshiba aquilion16) 22 s (phaseⅠ), 37-40 s (phaseⅡ) and 60 s (phase Ⅲ) after intravenous administration of contrast medium. Images were then obtained by CT colonography (CTC), X-ray projection (XRP), multi-planar reformation (MPR), surface shadow display (SSD), CT angiography (CTA) in post-procession workstation. The results were comparatively analyzed with the surgical pathology.

RESULTS: Sixty-four cancer lesions were detected on CT images and in surgery. They located in ascending colon (18 lesions), hepatic flexure of colon (2 lesions), transverse colon (4 lesions), splenic flexure of colon (2 lesions), descending colon (6 lesions), sigmoid (20 lesions, of which 5 lesions in the injunction of sigmoid and rectum), and rectum (12 lesions). Extracolonic diseases were found in 16 patients by MSCT or surgery. On multi-phase contrasted CT images, colon caner lesions demonstrated homogeneous or inhomogenous enhancement, and the absolutely increased peaks in CT density were at phase Ⅱ (30 lesions), phase Ⅱ-Ⅲ (17 lesions), phase Ⅲ (13 lesions) and phaseⅠ-Ⅲ (4 lesions). CTA detected blood-supplying artery of 58 cancer lesions (90.6%). The sensitivity, specificity and positive accuracy were 100%, 64.2%, and 92.1% respectively, for pericolonic fat involvement, and 78.5%, 86.7%, and 86.1% respectively, for abdominal metastasis-positive lymph-nodes.

CONCLUSION: MSCT pneumocolon and preoperative three-phase contrasted CT can provide information about tumor location, number, stage, blood-supplying artery and extracolonic diseases.

Gastric cancer: preoperative local staging with 3D multi-detector row CT--correlation with surgical and histopathologic results

PURPOSE

To prospectively evaluate accuracy of multi-detector row computed tomographic (CT) images for preoperative staging of gastric cancer by using surgical and histopathologic results as reference standards.

MATERIALS AND METHODS

This study had institutional review board approval; informed consent was obtained from all patients. Multi-detector row CT included acquisition of virtual gastroscopy images after air distention and contrast material-enhanced dynamic transverse and multiplanar reformation (MPR) images after water distention. Fifty-five consecutive patients with gastric cancer (38 men, 17 women; age range, 37-84 years; mean age, 63 years) underwent preoperative CT. All received 6 g of gas-producing crystals before unenhanced CT scanning for gastric distention and virtual gastroscopy. Patients drank 800-1000 mL of tap water to establish a background for dynamic contrast-enhanced CT scans. Images were obtained in late arterial, portal venous, and delayed phases with start delays of 40, 70, and 150 seconds, respectively. All patients underwent surgery. CT findings were compared with surgical and histopathologic results. Differences in accuracy of transverse and MPR images for T and N staging were assessed with the McNemar exact test. Statistical significance was inferred at P < .05.

RESULTS

Detection rates of primary tumors with transverse images, MPRs, and combinations of MPR and virtual gastroscopy images were 91% (50 of 55), 96% (53 of 55), and 98% (54 of 55), respectively. Overall accuracy in assessment of tumor invasion of the gastric wall (T stage) was significantly better with MPR images (89% [49 of 55]) than with transverse images (73% [40 of 55]) (P < .01). Overall accuracy for lymph node (N) staging was 78% (43 of 55) with MPR images and 71% (39 of 55) with transverse images. This difference was not significant (P = .103).

CONCLUSION

Multi-detector row CT with combined water and air distention can improve the accuracy of preoperative staging of gastric cancer. MPRs yield significantly better overall accuracy than transverse images for tumor staging but not for lymph node staging.

Preoperative diagnosis of lymph node metastases in gastric cancer by magnetic resonance imaging with ferumoxtran-10

BACKGROUND

Knowledge regarding the presence and location of lymph node metastasis in gastric cancer is essential in deciding on the operative approach. Lymph node metastases have been diagnosed with imaging tests such as computed tomography (CT) and ultrasonography (US); however, the accuracy of such diagnoses, based on size and shape criteria, has not been adequate. Ferumoxtran-10 (Combidex; Advanced Magnetics) is a lymphotropic contrast agent for magnetic resonance imaging (MRI) whose efficacy for the detection of metastatic lymph nodes in various cancers has been reported by several investigators; however, its efficacy for this purpose has not been reported for gastric cancer. We investigated the efficacy of ferumoxtran-10-enhanced MRI for the diagnosis of metastases to lymph nodes in gastric cancer.

METHODS

Seventeen consecutive patients who were diagnosed with a nonearly stage of gastric cancer were enrolled in the study. All the patients were examined by MRI (Signa Horizon 1.5 T; GE Medical; T2*-weighted images) before and 24 h after the intravenous administration of ultrasmall particles of superparamagnetic iron oxide--ferumoxtran-10 (2.6 mg Fe/kg of body weight)--and the presence or absence of metastasis was determined from the enhancement patterns. The imaging results were compared with the corresponding histopathological findings following surgery.

RESULTS

Of 781 lymph nodes dissected during surgery, the imaging results of 194 nodes could be correlated with their histopathological findings. Fifty-nine lymph nodes from 11 patients had histopathological metastases. In nonaffected normal lymph nodes, we observed dark signal intensity on MRI caused by the diffuse uptake of the contrast medium by macrophages resident in the lymph nodes, which phagocytose the iron oxide particles of ferumoxtran-10. The number of phagocytic macrophages was decreased in metastatic lymph nodes, and they showed various patterns of decreased uptake of ferumoxtran-10. Three enhancement patterns were observed in lymph nodes: (A) lymph nodes with overall dark signal intensity due to the diffuse uptake of ferumoxtran-10; (B) lymph nodes with partial high signal intensity due to partial uptake; and (C) no blackening of lymph nodes due to no uptake of ferumoxtran-10. Patterns (B) and (C) were defined as metastatic. The sensitivity, specificity, positive predictive value, negative predictive value, and overall predictive accuracy of postcontrast MRI were 100% (59/59), 92.6% (125/135), 85.5% (59/69), 100% (125/125), and 94.8% (184/194), respectively. These parameters for predictive accuracy were much superior to these parameters previously evaluated by CT or US. Nodes in the retroperitoneal and paraaortic regions were more readily identified and diagnosed on the MR images than those in the perigastric region.

CONCLUSION

The present study confirmed that ferumoxtran-10-enhanced MRI is useful in the diagnosis of metastatic lymph nodes and that the use of this modality will be helpful in treatment decision-making for gastric cancer patients.

Quantitative contrast-enhanced computed tomography: is there a need for system calibration?

The purpose of the study was to perform phantom studies to assess the impact of computed tomography (CT) system variability on quantitative measurements of contrast enhancement. A phantom containing tubes of contrast material at dilutions of 120, 1:35, 1:50, 1:100 and 1:200 arranged in air or water was imaged using 11 CT systems at 9 institutions. All systems had undergone routine calibration against air and water in accordance with the manufacturers' recommendations. For a given tube voltage, the relationship between the iodine concentration and CT attenuation value on a single system varied by 17 to 24% over 46-48 weeks. The coefficients of variance for iodine calibration factors across different CT systems were 8.9% in air and 5.1% in water. Calibration of individual CT systems for iodine response is required to allow comparison of quantitative measurements of contrast enhancement across different institutions. Using the iodine calibration factor to express contrast enhancement as iodine concentration would facilitate the universal application of diagnostic enhancement thresholds, especially if the necessary calculations were performed by software installed on the CT console.

Utility of multidetector CT in the diagnosis of gastric bare area invasion by proximal gastric carcinoma

PURPOSE

To investigate the utility of multidetector CT (MDCT) in the diagnosis of gastric bare area (GBA) invasion by proximal gastric carcinoma (PGC).

METHODS

Sixty-eight consecutive patients with biopsy-proven PGC underwent MDCT scan prior to gastrectomy. We evaluated the CT images separately for the site, size, depth, lymph node, and enhancement characteristic of each case. Each postsurgical stomach specimen was axially sectioned and comparison was made to determine the correlation between the CT findings and the pathological examination of each tumor bearing slice.

RESULTS

The sensitivity for detecting GBA involvement in patients with PGC was 84%. MDCT correctly identified 32 of 38 patients with GBA invasion and 10/13 (77%) tumors with metastatic lymph node greater than 5 mm in GBA or subphrenic retroperitoneal space. 33/36 (92%) patients with tumor extension within the edge of the gastric wall and 28/32 (88%) patients with tumor infiltration into subphrenic fat were correctly identified. MDCT correctly predicted the infiltration of tumor into the diaphragm in all 14 patients and identified 6/11 (55%) patients with gastrophrenic ligament invasion.

CONCLUSION

MDCT may be of value in assessing the important radiological characteristics of GBA invasion in patients with PGC.

Computed tomography of gastrocolic ligament: involvement in malignant tumors of the stomach

BACKGROUND

This study investigated computed tomographic (CT) features and anatomic bases of gastrocolic ligament involvement in malignant neoplasms of the stomach.

METHODS

We retrospectively reviewed CT scans of 34 patients known to have gastric malignant neoplasm and gastrocolic ligament involvement. Emphasis was placed on direct invasion, lymph node metastasis, and omental seeding.

RESULTS

CT manifestations of gastrocolic ligament involvement included direct invasion (38.2%, 13 of 34), enlargement of lymph nodes (50%, 17 of 34), "smudged" appearance (26.5%, nine of 34), "omental caking" (5.9%, two of 34), cystic mass (2.9%, one of 34), and varices of the omentum (2.9%, one of 34). We also found that gastric carcinoma and gastrointestinal stromal tumor invaded the transverse colon through the gastrocolic ligament in six patients (17.6%, six of 34).

CONCLUSION

CT scan is useful for detecting gastrocolic ligament involvement in gastric malignant neoplasm. The imaging features consist of a mass sign, enlargement of lymph nodes, smudged appearance, omental caking, and so on. Gastric malignant neoplasm also may involve the transverse colon through the gastrocolic ligament.

Selection of patients with gastric adenocarcinoma for laparoscopic staging

BACKGROUND

To refine selection criteria for laparoscopic staging of gastric adenocarcinoma, preoperatively available clinical and radiologic factors that may predict the risk of M1 disease were investigated.

METHODS

During 1993-2002, laparoscopy was performed if patients had minimal symptoms and there was no definite M1 disease at computed tomography (CT) scanning. High-quality, spiral, CT scans were reviewed in detail for 65 recent patients.

RESULTS

Laparoscopy was conducted for 657 patients and M1 was detected in 31%. M1 was significantly more prevalent with tumor location at the gastroesophageal junction (GEJ; M1 in 42%) or whole stomach (66%), poor differentiation (36%) or age < or = 70 years (34%). On spiral CT scan, lymphadenopathy > or = 1 cm (49%) or T3/T4 tumors (63%) were associated with significantly higher prevalence of M1. On multivariate analyses, only tumor location (GEJ or whole stomach) and lymphadenopathy were independently significant and M1 was not detected in any patient with neither risk factor.

CONCLUSIONS

With spiral CT staging, laparoscopy may be avoided if the primary tumor is not at the GEJ or whole stomach and there is no lymphadenopathy.

CT and PET in stomach cancer: preoperative staging and monitoring of response to therapy

Stomach cancer is one of the leading causes of cancer mortality worldwide. Complete resection of a gastric tumor and adjacent lymph nodes represents the only potentially curative intervention. Computed tomography (CT) has remained the modality of choice for the preoperative staging of gastric cancer and for follow-up. A recently developed advanced CT technique that makes use of thin sections, optimal contrast material enhancement, and multiplanar reformation allows more accurate staging. However, CT may be limited in the identification of nonenlarged lymph node metastasis, peritoneal dissemination, and small hematogenous metastasis. Positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) has been recognized as a useful diagnostic technique in clinical oncology. FDG PET allows scanning of a larger volume than is possible with CT. Although FDG PET is not an appropriate first-line diagnostic procedure in the detection of stomach cancer and is not helpful in tumor staging, it may play a valuable role in the detection of distant metastases, such as those of the liver, lungs, adrenal glands, ovaries, and skeleton. FDG PET may also be helpful in the follow-up of patients undergoing chemotherapy, as it allows the identification of early response to treatment. Further studies are needed to determine the efficacy of FDG PET in the detection of local nodal metastases and peritoneal dissemination. Nevertheless, the combined use of CT and PET can be helpful in the preoperative staging of stomach cancer and in the therapeutic monitoring of affected patients.

A practical scoring system based upon ROC analysis for evaluating potential lymph nodes metastasis during gastric surgery

BACKGROUND AND OBJECTIVES

Current preoperative N staging does not offer an accurate estimation of lymph node involvement. We establish a new scoring system for predicting N stages to guide a rational lymphadenectomy for gastric cancer.

METHODS

Variables correlated with N stages were selected by multivariate stepwise logistic regression analysis. Variables granted the different scores according to the odds ratio (OR). Receiver operating characteristic (ROC) analysis was used to generate scoring ranges from N0 to N3. The agreement between predicted N staging and actual pN classification was analyzed using kappa statistics.

RESULTS

Tumor size, depth of invasion, and histological types were selected to establish the scoring system. Scores 0-4, 5-7, 8-9, and 10-13 were postulated to predict N0-3, respectively. The predicted N stage has good agreement with the actual pN classifications. The negative predictive values for N0-3 were 87.0, 86.4, 90.4, and 90.2%; the positive predictive values were 74.7, 62.8, 57.3, and 69.6%, respectively. The accuracy is 82% for N0-1, and 83.7% for N2-3.

CONCLUSIONS

The new scoring system can predict the N stage of gastric cancer. With its good negative predictive value, it is possible to minimize the potential hazards of applying a more extensive lymph node dissection than necessary.

Gastric cancer by multidetector row CT: preoperative staging

The role of computed tomography (CT) in the preoperative staging of gastric cancer, even if controversial, may be fundamental for evaluating the local extent and nodal involvement of the disease, especially in locally advanced cases. However, previous results of CT staging have not been satisfactory for predicting the invasive depth of the tumor or possible nodal metastases. Recently introduced multidetector row CT (MDCT) and three-dimensional (3D) imaging are expected to overcome the limitations in cancer staging by offering rapid and accurate information for space perception, detailed hemodynamics, and real-time 3D processing of volumetric data sets. In particular, virtual endoscopic imaging may be helpful for detecting early gastric cancer. In our experience, T and N stagings of gastric cancer were improved with 3D MDCT when using volume rendering and virtual endoscopic imaging compared with conventional axial two-dimensional (2D) CT (accuracy of T staging with 3D vs. 2D CT images, 84% vs. 77%; accuracy of N staging, 63% vs. 61% with 3D vs. 2D images, respectively). In particular, the detection rate of early gastric cancer was markedly increased up to 96% when using 3D MDCT. Therefore, we believe that 3D MDCT of the stomach may enhance the performance of CT in the preoperative evaluation of patients who have gastric cancer by offering easy early detection of lesions and accurate tumor staging through the 3D imaging process.

Clinical value of multidetector row computed tomography in detecting lymph node metastasis of early gastric cancer

AIMS

To evaluate the clinical value of multidetector row computed tomography (MDCT) as a pre-operative staging tool for lymph node metastasis in patients with early gastric cancer (EGC).

METHODS

In 278 consecutive patients with EGC, lymph node metastasis was evaluated pre-operatively with MDCT at a slice thickness of 2.5mm (n=57), 5.0mm (n=188), or 7.5mm (n=33).

RESULTS

Overall accuracy of nodal category from N0 to N3 was 86% for MDCT and 95% for operative assessment. Regarding accuracy in detecting at least one metastatic lymph node, area under curves (AUC) of receiver operating characteristics for 2.5, 5.0, and 7.5-mm slices and assessment during surgery were 0.87, 0.67 and 0.47, and 0.70, which were significantly different (P<0.0001). MDCT image with 2.5-mm could discriminate the presence of lymph node metastasis with diagnostic accuracy: sensitivity 80%; specificity 92%; positive predictive value (PPV) 50%; negative predictive value (NPV) 98%, whereas assessment during surgery was as follows: sensitivity 65%; specificity 98%; PPV 72%; and NPV 97%.

CONCLUSIONS

These results suggest that pre-operative assessment with MDCT using thinner slices may detect at least one lymph node metastasis as accurately as assessment during surgery for patients with EGC.

Gastric cancer

Gastric cancer is one of the most common cancers and one of the most frequent causes of cancer-related deaths. The incidence, diagnostic studies, and therapeutic options have undergone important changes in the last decades, but the prognosis for gastric cancer patients remains poor, especially in more advanced stages. Surgery is the mainstay of treatment of this disease, even if it is associated with a high rate of locoregional and distant recurrence. There is ongoing debate regarding the role of adjuvant treatment In advanced disease, palliation of symptoms, rather than cure, is the primary goal of patient management. Several combination therapies have been developed and have been examined in phase III trials; however, in most cases, they have failed to demonstrate a survival advantage over the reference arm. This review summarizes the most important recommendations for the management of patients with gastric cancer.

Evaluation of contrast-enhanced helical hydro-CT in staging gastric cancer

AIM: To discuss the helical computed tomography (CT) characteristics of gastric cancer and evaluate the diagnostic value of contrast-enhanced helical hydro-CT (HHCT) in staging gastric cancer.

METHODS: A total of 50 patients with gastric cancer were included in this study. The CT findings in them were retros-pectively analyzed and correlated with pathologic findings at surgery. All patients were preoperatively imaged by plain and contrast-enhanced helical CT after orally ingesting 1 000-1 500 mL water. Peristalsis was minimized by intra-venous administration of spasmolytics.

RESULTS: The foci of gastric cancer became more prominent in all the 50 patients and showed strong enhancement in contrast-enhanced HHCT. The tumor was located at the gastric cardia in 14 cases, at the gastric fundus in 3 cases, at the gastric body in 8 cases, at the gastric antrum in 4 cases, at the gastric fundus and the body in 8 cases, at the gastric body and antrum in 11 cases, and at three segments of the stomach in 2 cases. The CT features of gastric cancer were focal or diffuse mural thickening, soft tissue mass, cancerous ulcer, stenosis of stomach, infiltration to adjacent tissues, lymph node and distant metastases. Strong contrast enhancement of the gastric wall was closely related to gastric cancer. The accuracy rate of contrast-enhanced HHCT in staging gastric cancer was 86% (43/50). The detection rate of lymph node metastases by CT was 60% (12/20).

CONCLUSION: Contrast-enhanced HHCT is a reliable method to diagnose and stage gastric cancer.