Helical hydro-CT for diagnosis and staging of gastric carcinoma

Current status and future perspectives on neoadjuvant therapy in gastric cancer

Gastric cancer, with high morbidity and mortality rates, is one of the most heterogeneous tumors. Radical gastrectomy and postoperative chemotherapy are the standard treatments. However, the safety and efficacy of neoadjuvant therapy (NAT) need to be confirmed by many trials before implementation, creating a bottleneck in development. Although clinical benefits of NAT have been observed, a series of problems remain to be solved. Before therapy, more contributing factors should be offered for choice in the intended population and ideal regimens. Enhanced computed tomography (CT) scanning is usually applied to evaluate effectiveness according to Response Evaluation Criteria in Solid Tumors (RECIST), yet CT scanning results sometimes differ from pathological responses. After NAT, the appropriate time for surgery is still empirically defined. Our review aims to discuss the abovementioned issues regarding NAT for GC, including indications, selection of regimens, lesion assessment and NAT-surgery interval time.

MDCT imaging of the stomach: advances and applications

The stomach may be involved by a myriad of pathologies ranging from benign aetiologies like inflammation to malignant aetiologies like carcinoma or lymphoma. Multidetector CT (MDCT) of the stomach is the first-line imaging for patients with suspected gastric pathologies. Conventionally, CT imaging had the advantage of simultaneous detection of the mural and extramural disease extent, but advances in MDCT have allowed mucosal assessment by virtual endoscopy (VE). Also, better three-dimensional (3D) post-processing techniques have enabled more robust and accurate pre-operative planning in patients undergoing gastrectomy and even predict the response to surgery for patients undergoing laparoscopic sleeve gastrectomy for weight loss. The ability of CT to obtain stomach volume (for bariatric surgery patients) and 3D VE images depends on various patient and protocol factors that are important for a radiologist to understand. We review the appropriate CT imaging protocol in the patients with suspected gastric pathologies and highlight the imaging pearls of various gastric pathologies on CT and VE.

[Gastroenteropancreatic endocrine tumors]

CLINICAL/METHODICAL ISSUE

Gastroenteropancreatic neuroendocrine tumors (GEP-NET) are a rare, heterogeneous group of neoplasms. Only 2% of gastrointestinal tumors belong to the group of neuroendocrine neoplasms.

STANDARD RADIOLOGICAL METHODS

A wide spectrum of diagnostic imaging modalities is available: apart from ultrasound not only computed tomography (CT) but also magnetic resonance imaging (MRI) and positron emission tomography CT (PET-CT) play an important role in detection and staging of GEP-NETs.

METHODICAL INNOVATIONS

The PET-CT technique with somatostatin analogues is used for staging as well as for evaluation and monitoring of treatment with peptide radionuclide radiation therapy.

PERFORMANCE

According to the literature NETs of the small bowel with a size over 3 cm can be detected with a sensitivity of 84.7% and a specificity of 96.6% using CT enteroclysis and MR enteroclysis provides the detection of NETs of the small bowel in 93.3% of cases. 'The sensitivity of MRI in detection of pancreatic NETs is between 74% and 100% and is, therefore, higher than CT. Detection of small primary tumors is carried out using PET-CT and seems to be the most sensitive imaging modality to identify the exact location. On the other hand MRI has to be regarded as the best imaging modality for detection of liver metastases compared to CT and PET-CT.

ACHIEVEMENTS

The role of diagnostic imaging is to identify the exact location of the primary tumor and possible metastases, to define an appropriate therapy and to monitor treatment effects; however, the choice of the most appropriate diagnostic imaging modality varies depending on the location and type of the primary tumor.

PRACTICAL RECOMMENDATIONS

The GEP-NETs are predominantly well-vascularized; therefore, dual-phase CT/MR imaging with the arterial and venous phases after contrast media injection is mandatory for detection and localization of primary tumors and metastases. For whole body staging CT and PET-CT should be performed.

CT enteroclysis/enterography findings in drug-induced small-bowel damage

OBJECTIVE

To evaluate the CT enteroclysis (CTE)/enterography findings of patients with small-bowel mucosal damage induced by aspirin or non-steroidal anti-inflammatory drugs (NSAIDs) and to compare these findings with the duration of drug use and endoscopic findings.

METHODS

CTE findings of 11 patients (22 lesions) with drug-induced small-bowel damage were reviewed, including 8 NSAID users and 3 aspirin users. Three patients were short-term users (6 months or shorter) and eight were long-term users (3 years or longer). Nine patients also underwent videocapsule endoscopy (VCE) or double-balloon enteroscopy (DBE).

RESULTS

Small-bowel abnormalities were visible in 8 of 11 patients (73%) on CTE. Multiple lesions were seen in five patients, including all short-term users. Lesions were classified into three types. Type 1 (mucosal patchy enhancement) was found in four of eight patients (50%, 12 lesions) all were short-term users. Small erosions with mild oedema/redness were shown by DBE. Type 2 (homogeneous hyperenhancement) was found in two of eight patients (25%, four lesions) who were long-term users. Large ulcers with marked oedema/redness were shown by DBE. Type 3 (stratification enhancement) was found in four of eight patients (50%, six lesions), both short-term and long-term users. Annular or large ulcers with strictures were shown by VCE or DBE.

CONCLUSION

On CTE, Type 1 lesions in patients with mostly short-term aspirin or NSAID use, Type 2 lesions in patients with long-term use and Type 3 lesions in both types of patients were detected. CTE may have usefulness for the detection of mild damage.

ADVANCES IN KNOWLEDGE

Small-bowel abnormalities owing to aspirin or NSAID present with three different patterns on CTE.

Accurate preoperative staging of gastric cancer with combined endoscopic ultrasonography and PET-CT

Accurate staging of gastric cancer is helpful to determine the most appropriate therapy, but no staging modality has been accepted as the standard. Objective is to evaluate the usefulness of endoscopic ultrasonograph (EUS) combined with position emission tomography and computed tomograph (PET-CT) in gastric cancer staging. A total of 124 patients confirmed with gastric cancer were subjected to staging with EUS and PET-CT scanning. The detection rate of primary tumor was 99.2% by combination use of two modalities and 97.6% by EUS alone (p = 0.6219), but the detection rate was 90.3% (112 of 124) by PET-CT alone (compared with the combination, p = 0.0027; compared with EUS alone, p = 0.0299). The locoregional lymph node invasion was identified in 84/124 (67.7%) by combined PET-CT and EUS, which was obviously higher than that with EUS (52.4%) or PET-CT (43.5%) alone (p = 0.0194 and p = 0.0002, respectively). There was no statistical difference in identification of celiac axis lymph node metastasis among three methods, but the combined examination or PET-CT alone was more effective than EUS alone in the detection of distant metastases (all p < 0.01). Furthermore, the combined EUS and PET-CT was more optimal than using EUS or PET-CT alone in the accurate T and N staging and the effect on change of treatment. The present study indicates that the combination of EUS and PET-CT is an ideal modality in the preoperative staging of gastric cancer and it provides beneficial guidance for the treatment of gastric cancer.

How useful is preoperative imaging for tumor, node, metastasis (TNM) staging of gastric cancer? A meta-analysis

BACKGROUND

Surgery is the fundamental curative option for gastric cancer patients. Imaging scans are routinely prescribed in an attempt to stage the disease prior to surgery. Consequently, the correlation between radiology exams and pathology is crucial for appropriate treatment planning.

METHODS

Systematic searches were conducted using Medline, Embase, and the Cochrane Central Register of Controlled Trials from January 1, 1998 to December 1, 2009. We calculated the accuracy, overstaging rate, understaging rate, Kappa statistic, sensitivity, and specificity for abdominal ultrasound (AUS), computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) with respect to the gold standard (pathology). We also compared the performance of CT by detector number and image type. A meta-analysis was performed.

RESULTS

For pre-operative T staging MRI scans had better performance accuracy than CT and AUS; CT scanners using ≥ 4 detectors and multi-planar reformatted (MPR) images had higher staging performances than scanners with <4 detectors and axial images only. For pre-operative N staging PET had the lowest sensitivity, but the highest specificity among modalities; CT performance did not significantly differ by detector number or addition of MPR images. For pre-operative M staging performance did not significantly differ by modality, detector number, or MPR images.

CONCLUSIONS

The agreement between pre-operative TNM staging by imaging scans and post-operative staging by pathology is not perfect and may affect treatment decisions. Operator dependence and heterogeneity of data may account for the variations in staging performance. Physicians should consider this discrepancy when creating their treatment plans.

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.

Prognostic significance of computed tomography defined ascites in advanced gastric cancer

PURPOSE

The aim of this study was to investigate the clinicopathologic features and prognosis in patients with computed tomography (CT) findings of ascites, with a focus on the correlation with peritoneal carcinomatosis.

METHODS

This study included a total of 157 patients who underwent surgery for advanced gastric cancer from 2003 to 2008 at the Department of Surgery, Hallym University Kangdong Sacred Heart Hospital, Seoul, Korea, which were analyzed retrospectively.

RESULTS

Fourteen patients (8.9%) presented ascites on their CT scan. Among them, 10 patients had peritoneal carcinomatosis, and showed significant difference with CT ascites positive group in the incidence of peritoneal carcinomatosis. The presence of CT ascites was significantly correlated with pathologic T stage, tumor size, histologic type, CT T and N stages, CT peritoneal nodularity and curability of surgery, statistically. The prognosis of CT ascites positive group was much poorer in the total advanced gastric cancer patients (P < 0.001), as well as in patients with pathologic T4 (P = 0.002). Also in patients without peritoneal carcinomatosis, CT ascites positive subgroup tended to have a worse prognosis than CT ascites negative subgroup (P = 0.086). Tumor size, CT T and N stages and the presence of CT peritoneal nodularity and ascites influenced the prognosis significantly; among which, if a tumor size larger than 5 cm, CT T4 stage and the presence of CT ascites were identified as independent prognostic factors.

CONCLUSION

The presence of ascites was closely associated with peritoneal metastasis, and was the most significant independent prognostic factor in advanced gastric cancer in the present study.

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.

Detection of early gastric cancer using hydro-stomach CT: Blinded vs unblinded analysis

AIM: To evaluate the difference in diagnostic performance of hydro-stomach computed tomography (CT) to detect early gastric cancer (EGC) between blinded and unblinded analysis and to assess independent factors affecting visibility of cancer foci.

METHODS: Two radiologists initially blinded and then unblinded to gastroscopic and surgical-histological findings independently reviewed hydro-stomach CT images of 110 patients with single EGC. They graded the visibility of cancer foci for each of three gastric segments (upper, middle and lower thirds) using a 4-point scale (1: definitely absent, 2: probably absent, 3: probably present, and 4: definitely present). The sensitivity and specificity for detecting an EGC were calculated. Intraobserver and interobserver agreements were analyzed. The visibility of an EGC was evaluated with regard to tumor size, invasion depth, gastric segments, histological type and gross morphology using univariate and multivariate analysis.

RESULTS: The respective sensitivities and specificities [reviewer 1: blinded, 20% (22/110) and 98% (215/220); unblinded, 27% (30/110) and 100% (219/220)/reviewer 2: blinded, 19% (21/110) and 98% (216/220); unblinded, 25% (27/110) and 98% (215/220)] were not significantly different. Although intraobserver agreements were good (weighted κ = 0.677 and 0.666), interobserver agreements were fair (blinded, 0.371) or moderate (unblinded, 0.558). For both univariate and multivariate analyses, the tumor size and invasion depth were statistically significant factors affecting visibility.

CONCLUSION: The diagnostic performance of hydro-stomach CT to detect an EGC was not significantly different between blinded and unblinded analysis. The tumor size and invasion depth were independent factors for visibility.

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.

Type IV collagen levels are elevated in the serum of patients with peritoneal dissemination of gastric cancer

Type III procollagen (amino-terminal propeptide of procollagen type III) and type IV collagen are considered to be reliable serum markers for monitoring the progression of liver fibrosis. The peritoneal dissemination of gastric cancer is also characterised by abundant collagen deposition in the peritoneum. The present study was performed to investigate the potential of serum type III procollagen and IV collagen as biomarkers for peritoneal dissemination in gastric cancer. The study population consisted of 117 patients with gastric cancer: 32 patients had peritoneal dissemination which was pathologically diagnosed by laparotomy or laparoscopic examination, while 85 patients (45/40, early/advanced gastric cancer) had no peritoneal dissemination. We measured the serum levels of type III procollagen and type IV collagen in comparison to the commonly accepted tumor markers carcinoembryonic (CEA), carbohydrate antigen (CA)19-9 and CA125. The median type III procollagen levels showed no significant differences between the two groups, whereas the median type IV collagen levels were significantly (201 ng/ml) higher in patients with than in those without peritoneal dissemination (early/advanced gastric cancer, 124/136 ng/ml) (P<0.05). In receiver operating characteristic (ROC) curve analysis, type IV collagen had the largest area under the curve (0.83), followed by CA125 (0.72), CA19-9 (0.64), CEA (0.59) and type III procollagen (0.48). Type IV collagen was an independent marker (P<0.0001, odds ratio 15.7) for predicting peritoneal dissemination along with CA125 (P=0.0086, odds ratio 9.4) based on multivariate logistic regression. In conclusion, serum type IV collagen levels may be significant in the early detection and management of patients with peritoneal dissemination of gastric cancer.

Computed tomography enteroclysis for recurrent severe gastrointestinal bleeding in a patient with vascular malformation of the small bowel

This is a case study of a 66-year-old woman who had a vascular malformation of the small bowel that was visualized on computed tomography enteroclysis (CTE). She presented with repeated tarry stool and severe anemia. Although the source of bleeding was not identified on upper and lower gastrointestinal endoscopy, active bleeding was revealed by capsule endoscopy in the deep jejunum. The cause of bleeding was not found on capsule endoscopy. CTE was requested as double-balloon endoscopy would have been difficult because of strong adhesion of the small intestine. A continual subtle vascular malformation of the jejunum, starting from the third jejunal branch end, was demonstrated on CTE with dynamic contrast enhancement. Because this vascular malformation was considered the cause of small intestinal bleeding, selective arterial coil embolization was performed. After embolization, the repeated tarry stool disappeared and the severe anemia dramatically improved. CTE may be a safe and useful method for determining the cause of small intestinal bleeding and for subsequent therapy.

Peritoneal metastasis: detection with 16- or 64-detector row CT in patients undergoing surgery for gastric cancer

PURPOSE

To retrospectively measure the diagnostic performance of prospective computed tomographic (CT) results obtained by using 16- or 64-detector row scanners in the detection of peritoneal metastases (PMs) in patients with advanced gastric cancer.

MATERIALS AND METHODS

The institutional review board approved this retrospective study and waived the need to obtain patient consent. In 498 patients with gastric cancer (stage >or= T2) who were undergoing surgery, the presence of PM was prospectively rated as grade 0 (absent), grade 1 (equivocal), or grade 2 (present) on CT scans (0.67 or 2 mm thick) that were interpreted by interactively adjusting the viewing thickness and viewing plane. The CT readings were retrospectively compared with surgical and pathologic findings. In patients in whom the presence of PM was rated as grade 1 or less, factors predictive of PM were identified by testing variables, including patient and tumor characteristics, with univariate tests and multivariate logistic regression analysis.

RESULTS

Fifty-three patients (10.6%) had confirmed PM. When only grade 2 was considered to indicate a positive CT reading, sensitivity and specificity were 28.3% (15 of 53) and 98.9% (440 of 445), respectively. With the threshold of grade 1 or greater indicating a positive reading, sensitivity and specificity were 50.9% (27 of 53) and 96.2% (428 of 445), respectively. In the patients with grades of 1 or less, the significant factors predictive of PM were greater tumor size and T stage.

CONCLUSION

The sensitivity of PM detection is limited, even with modern CT techniques. In patients whose CT results are not definitely positive for PM, staging laparoscopy is still recommended if the aforementioned two predictive factors (greater tumor size and T stage) are suspected.

Value of multidetector-row computed tomography in the preoperative T and N staging of gastric carcinoma: a large-scale Chinese study

OBJECTIVES

To investigate the value of multidetector-row computed tomography (MDCT) in the preoperative T and N staging of gastric carcinoma and to further investigate the clinicopathological factors affecting the diagnostic accuracy.

METHODS

Seven hundred ninety gastric carcinoma patients underwent preoperative MDCT examination. The results of MDCT were compared with surgical and pathological findings.

RESULTS

Early gastric carcinoma patients whose primary tumor was detected by MDCT had higher incidence of lymph node metastasis, larger tumor size, and deeper invasion. The overall accuracy of MDCT in determining T stage of gastric carcinoma was 73.80% (T1 45.93%, T2 53.03%, T3 86.49%, and T4 85.79%). The overall accuracy of MDCT in preoperative N staging was 75.22% (N0 76.17%, N1 68.81%, and N2 80.63%). The overall diagnostic sensitivity, specificity, and accuracy of MDCT for determining lymph node metastasis was 86.26%, 76.17%, and 82.09%, respectively. Multivariate analysis showed that the diagnostic sensitivity of MDCT in determining lymph node metastasis related with tumor size, N stage, and number of metastatic lymph nodes.

CONCLUSIONS

The clinical value of MDCT in the preoperative T and N staging of gastric carcinoma is relatively high. MDCT can be the first choice for the preoperative evaluation of patients with gastric carcinoma.

MRI of gastric carcinoma: Results of T and N-staging in an in vitro study

AIM: To determine the accuracy of 1.5-T magnetic resonance imaging (MRI) in the evaluation of gastric wall invasion and perigastric lymph node metastasis in gastric adenocarcinoma.

METHODS: Twenty resected gastric specimens containing 20 tumors were studied with a 1.5-T MR system using a commercial head surface coil. MR scanning was performed with a T1 weighted image (TR/TE = 500/20), and a T2 weighted image (TR/TE = 2500/90). MR findings were compared with pathologic findings.

RESULTS: A T1-weighted image demonstrated three layers in the normal gastric wall. All of the gastric tumors were well demonstrated by lesions and location. In a MRI findings of gastric wall invasion, there was 1 case of T1, 7 of T2, 11 of T3. Pathologic results of resected specimens included 3 cases of pT1, 4 of pT2, and 12 of pT3. The accuracy of T staging with MRI was 74% (14 of 19). MRI findings of lymph node metastasis included 6 cases of N0, 13 cases of N1. The accuracy of the N staging with MRI was 47% (9 of 19).

CONCLUSION: MRI has a high diagnostic accuracy in the evaluation of the T staging of gastric cancer in vitro and thus potentially enables preoperative histopathologic staging.

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.

Prediction of recurrence of early gastric cancer after curative resection

BACKGROUND

Recurrence of early gastric cancer (EGC) after curative resection is rare, and the types of EGC that may recur have not been well studied. We attempted to create a system for predicting recurrence of EGC after R0 resection.

METHODS

From January 1987 to April 2005, 2,923 patients with EGC who underwent curative resection were retrospectively studied. Of them, 79 patients (2.7%) experienced recurrence. Logistic regression was performed to identify independent risk factors for overall recurrence and early recurrence (recurred within 24 months after resection) of EGC. A nomogram was developed on the basis of a Cox regression.

RESULTS

Median time to recurrence was 20.5 months, and early recurrence accounted for 60.7% of instances. Presence of lymph node metastasis and elevated gross type were independent risk factors for overall recurrence; patients with both identified risk factors had a higher recurrence rate than average level (17.5% vs. 2.7%, P < 0.001). Meanwhile, male gender, elevated gross type, and presence of lymph node metastasis were significantly associated with early recurrence, and in patients with all of the aforementioned identified risk factors, the early recurrence rate was higher (12.2% vs. 1.6%, P < 0.001). A nomogram for predicting the disease-free survival after operation was constructed. Its c-index was 0.79 and it appeared to be accurate.

CONCLUSIONS

Recurrence of EGC after curative resection can be predicted by using common clinical characteristics. Patients at high risk of overall and early recurrence could be identified; individual disease-free survival was predictable by the internally validated nomogram.

64 multidetector-row computed tomography for preoperative evaluation of gastric cancer: histological correlation

OBJECTIVE

To assess the accuracy of 64 multidetector-row computed tomography (MDCT) in the diagnosis and staging of gastric cancer.

METHODS

This study was approved by the institutional review board, and the patients involved gave informed consent. Forty-four patients (34 men and 10 women; mean age, 57 years) with gastric carcinoma underwent preoperative 64 MDCT (SOMATOM Sensation 64; Siemens Medical System, Forchheim, Germany; slice collimation, 0.6 mm; slice width, 5 mm; feed/rotation, 23 mm; pitch factor, 1.2; kernel, B30f; and gantry speed, 0.5 second per rotation). Gastric distension was achieved by ingestion of 8 g of effervescent granules. Scanning was performed during arterial and portal phases, as determined with bolus tracking and automated triggering technique after intravenous administration of 100 mL of contrast materials (4 mL/s). All computed tomography scans were retrospectively reviewed by 2 radiologists. Each tumor was staged according to the TNM classification system. All patients underwent surgery. Computed tomography results were compared with histological staging of tumor invasion depth and regional lymph node metastasis.

RESULTS

The accuracy of 64 MDCT for detection of gastric cancer was 90% (18/20) and 100% (24/24) in early and advanced gastric cancer, respectively, with an overall detection rate of 95% (42/44). Its accuracy for determination of tumor penetration depth was 89% (16/18) and 88% (21/24) in early and advanced gastric cancer, respectively, with an overall accuracy of 88% (37/42). Its accuracy for determination of lymph node metastasis was 90% (18/20) and 71% (17/24) in early and advanced gastric cancer, respectively, with an overall accuracy of 80% (35/44).

CONCLUSIONS

The 64 MDCT is a promising technique for the detection and preoperative staging of gastric cancer.

Comparison of CT and 18F-FDG pet for detecting peritoneal metastasis on the preoperative evaluation for gastric carcinoma

OBJECTIVE

The aim of our study was to compare the accuracy of CT and (18)FFDG PET for detecting peritoneal metastasis in patients with gastric carcinoma.

MATERIALS AND METHODS

One-hundred-twelve patients who underwent a histologic confirmative exam or treatment (laparotomy, n = 107; diagnostic laparoscopy, n = 4; peritoneal washing cytology, n = 1) were retrospectively enrolled. All the patients underwent CT and (18)F-FDG PET scanning for their preoperative evaluation. The sensitivities, specificities and accuracies of CT and (18)FFDG PET imaging for the detection of peritoneal metastasis were calculated and then compared using Fisher's exact probability test (p < 0.05), on the basis of the original preoperative reports. In addition, two board-certified radiologists and two board-certified nuclear medicine physicians independently reviewed the CT and PET scans, respectively. A receiver-operating characteristic curve analysis was performed to compare the diagnostic performance of CT and (18)F-FDG PET imaging for detecting peritoneal metastasis.

RESULTS

Based on the original preoperative reports, CT and (18)F-FDG PET showed sensitivities of 76.5% and 35.3% (p = 0.037), specificities of 91.6% and 98.9% (p = 0.035), respectively, and equal accuracies of 89.3% (p = 1.0). The receptor operating characteristics curve analysis showed a significantly higher diagnostic performance for CT (Az = 0.878) than for PET (Az = 0.686) (p = 0.004). The interobserver agreement for detecting peritoneal metastasis was good (kappa value = 0.684) for CT and moderate (kappa value = 0.460) for PET.

CONCLUSION

For the detection of peritoneal metastasis, CT was more sensitive and showed a higher diagnostic performance than PET, although CT had a relatively lower specificity than did PET.

Magnetic resonance imaging for local staging of gastric carcinoma: results of an in vitro study

OBJECTIVE

Preoperative staging of gastric carcinoma is limited by the fact that available imaging modalities do not enable accurate evaluation of the depth of infiltration of the gastric wall. The aim of this study was to evaluate the efficiency of conventional magnetic resonance imaging (MRI) in local staging of gastric carcinoma.

METHODS

Sixty-five specimens of patients with proven gastric carcinoma were examined immediately after gastrectomy. Examination was performed with a 1-T MRI and included T1-weighted, T2-weighted, and opposed phase images. Images were analyzed for the number of visible wall layers and their signal intensity characteristics, for tumor localization and depth of infiltration. T-stage was classified according to the TNM system. Finally, the staging by MRI was compared with the histopathological staging of the specimens.

RESULTS

The mucosal, submucosal, and proper muscle layers could be differentiated by the typical signal intensities. Depiction of the subserosa or serosa was not possible. In 65 specimens, 67 carcinomas were found by the pathologist. Sixty-four of 67 (96%) histologically proven carcinomas were correctly localized by MRI; T-staging accuracy was 50% only, mainly because of overstaging pT2 tumors as T3.

CONCLUSIONS

MRI enables differentiation of gastric wall layers and, therefore, technically allows the evaluation of the local tumor stage of gastric carcinomas. However, infiltration of the subserosal and serosal layer cannot be proved accurately. Overstaging pT2 tumors is one of the most predominant problems. Yet further technical developments in high-resolution imaging of the gastric wall may improve T-staging in the near future and overcome today's staging limitations.

Radiologische Bildgebung des oberen Gastrointestinaltraktes

CT, and multi-detector row computed tomography in particular, play a very important role in staging malignant tumors of the stomach. The optimized technique of so called "Hydro-CT", including distension to the gastric wall with 1-1.5 l oral contrast media, mainly water, has fostered the diagnostic value of CT in the diagnosis of diseases of the stomach. By using the "Hydro-CT" technique, the detection rate for gastric carcinoma is now between 89% and 94%, and for liver metastasis between 85% and 92%. For overall T staging, the sensitivity is rather low at between 43% and 65%, and for the lymph nodes between 64 and 88%. Depending on tumor type, multislice computed tomography (MSCT) supplies morphological details for defining the type of lesion (polyps, gastritis, lymphoma, gastrointestinal stromal tumours, carcinoma). Nevertheless, a definite differential diagnosis remains difficult. In addition, multiplanar reconstruction (MPR), derived from multi-detector row computed tomography data sets, is very helpful in localizing these pathologies and demonstrating their anatomic relationship to adjacent organs and vascular structures. MRI plays no major part in the diagnostic evaluation of the upper GI-tract.

New coil concept for endoluminal MR imaging: initial results in staging of gastric carcinoma in correlation with histopathology

Our aim was to conduct a prospective study to evaluate staging accuracy of a new coil concept for endoluminal magnetic resonance imaging (MRI) on ex vivo gastric carcinomas. Twenty-eight consecutive patients referred to surgery with a clinically proven primary gastric malignancy were included. Surgical specimens were examined with a foldable and self-expanding loop coil (8-cm diameter) at 1.5 Tesla immediately after total gastrectomy. T1- and T2-weighted and opposed-phase sequences (axial, frontal sections; 3- to 4-mm slice thickness) were acquired. Investigators blinded to any patient information analyzed signal intensity of normal gastric wall, gastric tumor, and lymph nodes. Findings were compared with histopathological staging. On surgical specimens, 2-5 gastric wall layers could be visualized. All gastric tumors (26 carcinomas, two lymphomas) were identified on endoluminal MR data (100%). Overall accuracy for T staging was 75% (18/24); sensitivity to detect serosal involvement was 80% and specificity 89%. N staging correlated in 58% (14/24) with histopathology (N+ versus N-). The endoluminal coil concept is feasible and applicable for an ex vivo setting. Endoluminal MR data provided sufficient detail for gastric wall layer differentiation, and therefore, identification of T stages in gastric carcinoma is possible. Further investigations in in vivo settings should explore the potential of our coil concept for endoluminal MR imaging.

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.

Diagnosis of gastric cancer with MDCT using the water-filling method and multiplanar reconstruction: CT-histologic correlation

OBJECTIVE

The purpose of this study was to assess the utility of MDCT with a thin-sliced multiplanar reconstruction (MPR) technique and water-filling method for the diagnosis of gastric cancers.

MATERIALS AND METHODS

Sixty-five patients with gastric cancers were preoperatively examined with MDCT using the water-filling method. The abdomen was dynamically scanned at 30 and 80 sec after the start of contrast medium administration. MPR images were reconstructed with a slice width of 1.25 mm and a slice interval of 1 mm. The detection rate and accuracy of T staging for gastric cancer were evaluated on MPR images and compared with 5-mm-slice axial images. In addition, MDCT images were correlated with pathologic findings.

RESULTS

The detection rate of all gastric cancers using the MPR technique was 65%. The detection rate of advanced gastric cancers was 96.2% (25 of 26), whereas that of early gastric cancers was 41.2% (14 of 34). There was a statistically significant difference (p < 0.05) in the detection rate of early gastric cancers between MPR and 5-mm-slice axial images. The MDCT appearances of gastric cancers were well correlated with pathologic findings such as mucinous component or differences in infiltration of cancer cells. The overall accuracy of CT staging was 85%. MPR images were superior to axial images for the evaluation of the z-axis extent of tumor.

CONCLUSION

MDCT with the water-filling method has advantages in acceptable evaluation of depth invasion of gastric carcinomas and in visualization of histologic changes in the tumors. MPR images may be a useful guide for the evaluation of the z-axis extent of tumor.

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.

Magnetic Resonance Imaging Gastrography

OBJECTIVES

We sought to demonstrate the feasibility of depicting gastric tumors using magnetic resonance imaging (MRI) while applying the dark lumen technique. The findings were correlated with conventional gastroscopy. In addition, we evaluated the screening for lymph nodes and liver metastases during the same session to identify potential tumor spread.

MATERIALS AND METHODS

The study included 15 patients with known malignant gastric disease. Conventional gastrointestinal endoscopy was performed in all patients as gold standard. All patients were examined with computed tomography for tumor staging. MRI was performed using 1 L of tap water as oral contrast agent for all protocols. The MRI program included an axial T1-weighted (T1w; 2D-FLASH) sequence, an axial STIR and T2w (TSE) sequence, and 2 postcontrast T1w (3D coronal /2D axial FLASH) sequences using 0.2 mmol/kg gadolinium diethylenetriaminepenta-acetic acid as intravenously injected contrast agent. Qualitative analysis and comparison with conventional gastroscopy were performed.

RESULTS

The images obtained with the postcontrast 3D coronal T1w-FLASH sequence were the most suitable in identifying gastric tumors. Complete correlation with conventional gastroscopy was achieved in 80% of the cases and partial correlation in 13% of the cases. The same imaging sequence was also appropriate for the evaluation of lymph nodes. For the identification of liver metastases, the images obtained with the axial postcontrast T1w 2D-FLASH sequence provided a higher diagnostic confidence as compared with other imaging protocols.

CONCLUSIONS

Applying the dark lumen technique through MRI is suitable for imaging gastric tumors and has the potential to become a "one-stop shopping" method because of the possibility for lymph node evaluation and screening for metastases during the same session based on the same images.

Improvement in preoperative staging of gastric adenocarcinoma with positron emission tomography

BACKGROUND

Positron emission tomography (PET) with 18- fluorodeoxyglucose (FDG) has been used to both detect and stage a variety of malignancies. The current study examined the value of PET for preoperative staging of gastric adenocarcinoma.

METHODS

Sixty-eight patients (49 males and 19 females) with gastric adenocarcinoma, who were referred for preoperative FDG-PET scans, were enrolled in this study. The patients underwent spiral-computed tomography (CT) within 1 week of referral. The final diagnosis in all patients was made by histologic and surgical findings. For quantitative PET analysis, the regional tumor FDG uptake was measured by the standardized uptake value (SUV).

RESULTS

For the primary tumor of a gastric adenocarcinoma, PET demonstrated an increased uptake in 64 of 68 patients (sensitivity, 94%), with a mean SUV of 7.0 (range, 0.9-27.7). A comparison of FDG uptake and clinicopathologic features showed significant association between FDG uptake and macroscopic type, tumor size, lymph node metastasis, histologic type, and TNM stage. The PET scan had a similar accuracy with that of CT for diagnosing local and distant lymph node metastases as well as peritoneal status. In assessing local lymph node status, however, PET had a higher specificity than CT (92% vs. 62%, P = 0.000). Moreover, PET had additional diagnostic value in 10 (15%) of 68 patients by upstaging 4 (6%) and downstaging 6 (9%) patients. PET combined with CT was more accurate for preoperative staging than either modality alone (66% vs. 51%, 66% vs. 47%, respectively; P = 0.002).

CONCLUSIONS

FDG-PET improves the preoperative TNM staging of gastric adenocarcinoma. Based on its superior specificity, FDG-PET can facilitate the selection of patients for a curative resection by confirming a nodal status identified by CT.

Preoperative staging of gastric adenocarcinoma: comparison of helical CT and endoscopic US

PURPOSE

To compare the performance of helical computed tomography (CT) and endoscopic ultrasonography (US) in the preoperative staging of gastric cancer.

MATERIALS AND METHODS

Fifty-one consecutive patients with a primary malignant gastric tumor (stage T2-T4) were preoperatively evaluated with both helical CT and endoscopic US within 3 days. Each tumor was staged according to the TNM classification system with both modalities. All patients subsequently underwent surgery. Results of CT and endoscopic US were compared with histologic staging of tumor invasion depth and regional lymph node metastasis. For comparison of CT and endoscopic US data, the marginal homogeneity test was used, and a P value of less than.05 was determined to indicate statistical significance.

RESULTS

In comparison with histologic results, CT achieved correct T staging in 39 patients (76%) and correct N staging in 35 patients (70%). The corresponding results for endoscopic US achieved correct T staging in 44 patients (86%) and correct N staging in 45 patients (90%). There was no significant difference between T staging (P =.55) and N staging (P >.99). Because of challenging detection of wall layers, correct T staging was difficult for CT and endoscopic US in the differentiation of T2 and T3 lesions.

CONCLUSION

Compared with endoscopic US, helical CT focused on the stomach provides valuable results regarding T and N staging in patients with gastric cancer.

Prospective comparison of endoscopy, endosonography and computed tomography for staging of tumours of the oesophagus and gastric cardia

BACKGROUND

Local and multimodal therapeutic strategies for tumours of the oesophagus and gastric cardia, require precise preoperative staging. Endosonography is considered the most accurate staging method, while computed tomography (CT) has limitations especially in the evaluation of local infiltration. Macroscopic endoscopic evaluation was reported to be accurate in selected series, but no study has yet compared all three staging modalities.

METHODS

One hundred and seventeen unselected patients with tumours of the oesophagus and gastric cardia were prospectively staged first by the endoscopic macroscopic appearance and then by endosonography. All patients had preoperative CT scans, however, only the 36 patients receiving the scans at our institution were included in the study. The preoperative staging results were then compared to postoperative histology which was available as the gold standard in all included patients. Kappa statistics were used to exclude chance agreement of the clinical staging results with the pathohistological findings. Differences between the resulting kappa values for the different staging modalities were analysed with a jack-knife test.

RESULTS

Endoscopic macroscopic staging and endosonography (accuracy 67 and 69%, weighted kappa 0.78 and 0.84) were significantly more accurate than CT (accuracy 33%, weighted kappa 0.44) for determination of the T category (p = 0.006 and p = 0.001). After exclusion of tumours of the cardia (n = 33), the accuracy of macroscopic and endosonographic staging (accuracy 72 and 75%, weighted kappa 0.86 and 0.88) increased and remained more accurate than CT (accuracy 50%, weighted kappa 0.62). The main pitfall in our series in staging the T category was the overestimation of T2 tumours in the cardia as T3 or even as T4 tumours due to the inability to visualise the serosa. The accuracy of predicting lymph node metastasis was 68% for macroscopic endoscopic, 79% for endosonographic, and 67% for CT staging. Only endosonographic staging was significantly different from chance agreement with histology (weighted kappa = 0.56). Endosonographic staging was significantly more accurate than endoscopic macroscopic and CT staging (p = 0.03).

CONCLUSIONS

Endosonography is the most accurate staging modality for overall preoperative staging of oesophageal and cardial tumours. Endoscopic macroscopic staging allows a reasonably accurate assessment of the T category.

Carcinoma of stomach and duodenum: radiologic diagnosis and staging

Gastric carcinoma is one of the leading causes of cancer mortality worldwide. Accurate preoperative staging of gastric cancer is important in planning the most effective therapy toward cure or palliation. This article reviews the radiologic diagnosis and staging of gastric cancer.

Mucinous versus nonmucinous gastric carcinoma: differentiation with helical CT

PURPOSE

To assess the capability of helical computed tomography (CT) to assist in the differentiation between mucinous and nonmucinous gastric carcinomas, with a focus on the thickened stomach wall itself.

MATERIALS AND METHODS

In 62 patients with pathologically proved mucinous (n = 21) or nonmucinous (n = 41) gastric carcinomas, contrast material-enhanced helical CT images were obtained. The gross appearance, contrast enhancement pattern, predominant thickened layer, and degree of enhancement were retrospectively evaluated. Statistical analyses were performed with Fisher exact, chi(2), and Student t tests. A P value of less than.05 was considered to indicate a statistically significant difference.

RESULTS

The most common type of gross appearance in both carcinomas was fungating: It occurred in 71% of patients with mucinous carcinomas and in 59% of patients with nonmucinous carcinomas. The next most common gross appearance type was ulcerative (24% of patients) in nonmucinous carcinomas and diffusely infiltrative (29% of patients) in mucinous carcinomas (P =.009). The most common contrast enhancement pattern was homogeneous (61% of patients) in nonmucinous carcinomas and layered (62% of patients) in mucinous carcinomas (P =.001). These findings were significantly different. The predominantly affected thickened layer was the high-attenuating inner layer or the entire layer (88% of patients) in nonmucinous carcinomas and the low-attenuating middle or outer layer (57% of patients) in mucinous carcinomas. Only two mucinous tumors showed miliary punctate calcifications in infiltrative lesions.

CONCLUSION

Helical CT may assist in distinguishing mucinous from nonmucinous gastric carcinoma, primarily on the basis of enhancement pattern, predominant layer of the thickened wall, gross appearance, and presence of calcifications.

Gastric mucosa-associated lymphoid tissue lymphoma: helical CT findings and pathologic correlation

OBJECTIVE

The purpose of this study was to describe helical CT findings of gastric mucosa-associated lymphoid tissue (MALT) lymphoma and to correlate them with pathologic findings.

MATERIALS AND METHODS

We retrospectively reviewed CT examinations of 58 patients with confirmed gastric MALT lymphomas. Using the histopathologic grade of the MALT lymphomas, we divided the patients into two groups: those with high-grade lymphoma (n = 21) and those with low-grade lymphoma (n = 37). Common CT findings for the two groups were reviewed and compared.

RESULTS

Forty (69%) of the 58 patients showed at least one abnormality of the stomach on CT. Abnormalities included diffuse or segmental gastric wall thickening (66%, 38/58), lymphadenopathy (40%, 23/58), ulcer (22%, 13/58), and gastric mass (3%, 2/58). Eighteen (31%) of 58 patients were found to have no abnormality. The high-grade group had a higher incidence of abnormalities seen on CT than the low-grade group (100% vs 51%, respectively). Gastric wall thickening in the high-grade group was more diffuse (48% vs 8%) and severe (71% vs 14%; severe or moderate) than that seen in the low-grade group. Lymphadenopathy was visualized in 67% of the high-grade group and in 24% of the low-grade group. Gastric ulcer was found in 57% of the high-grade group and in only 5% of the low-grade group. The gastric mass formation was seen in only two patients in the high-grade group.

CONCLUSION

The CT findings of gastric MALT lymphoma that the two groups had in common were gastric wall thickening and lymphadenopathy. Although our results pointed to no specific CT finding for differentiating high-grade from low-grade gastric MALT lymphomas, we found that the absence of abnormality on CT is highly predictive of low-grade MALT lymphoma.

A resource utilization projection study of EUS

BACKGROUND

EUS has emerged as standard practice with respect to the diagnosis and staging of GI malignancies. Whether currently available resources are sufficient to meet the potential need for EUS is uncertain. This study examines the hypothetical demand for EUS in the United States.

METHODS

EUS cases performed at 3 centers with well-established expertise in EUS in 1997 were retrospectively reviewed and trends were extrapolated to national cancer statistics. Indications for EUS fell into 3 categories: (1) diagnosis/staging of esophageal, gastric, pancreatic, or rectal cancers (established indications); (2) suspected GI malignancy (obligate "rule out"); and (3) "other" (emerging indications). Hypothetical total numbers of cases in which EUS could be performed in the United States were calculated taking into consideration the expected number of GI malignancies for which EUS would be appropriate (based on cancer statistics for 2000), the fraction unresectable by CT, the fraction of elderly nonsurgical candidates, proportionate "rule out" cases, as well as "other" emerging indications.

RESULTS

The calculated hypothetical number of cases (United States) in which EUS would be indicated is 79,568 per year (10,287 esophagus, 10,666 stomach, 23,069 pancreas, and 35,546 rectal). If "other" indications remained constant at 12%, there would potentially be 89,116 EUS procedures performed per year, with a conservative estimate of 79,572 per year.

CONCLUSIONS

This model suggests that currently available EUS resources are not sufficient to meet hypothetical demand. Future considerations include the number of endoscopy units in which EUS is performed, the capacity of individual units, and the implications for training programs in the United States.

Comparison of hydro-US and spiral CT in the staging of gastric cancer

The purpose of this study was to compare the diagnostic accuracy of hydro-ultrasonography (US) and spiral computed tomography (CT) in the staging of gastric cancer. Forty-three patients with gastric cancers confirmed at surgery underwent hydro-US and spiral CT on the same day prospectively. Hydro-US and spiral CT were done after ingestion of water. US and CT images were independently analyzed. After surgery, pathological findings according to TNM classification were compared with US and CT findings. The detection rate for T1 tumors was 75% (12/16), and all T2-T4 tumors were detected (27/27). In the T class, good correlation with pathology occurred in 55.8% of cases for US and 58.1% for CT, and there was no difference in staging accuracy between US and CT (P=.7667). Overstaging occurred in 14% for US and CT. Understaging occurred in 30.2% for US and 27.9% for CT. In the N class, good correlation with pathology occurred in 60.5% for US and 55.8% for CT, and there was no difference in staging accuracy between US and CT (P=.0949). Overstaging occurred in 4.7% for US and 18.6% for CT, and understaging occurred in 34.9% and 25.6%, respectively. The diagnostic accuracy of hydro-US and spiral CT in the staging of gastric cancer was between 55.8% and 60.5%, and there was no significant difference in staging accuracy between hydro-US and spiral CT, except for a tendency to overstaging by CT and understaging by US in the N class (P<.05).

Role of computerized tomography in the staging of gastrointestinal neoplasms

Gastrointestinal neoplasms are very common diseases, and the first challenge for clinicians is to define the extent of the tumor in order to plan the best treatment. The role of computerized tomography in assessing this kind of patient is well established worldwide. This article reviews the capabilities and the limits of this imaging technique in the staging of the tumors of the digestive tract (liver, gallbladder, biliary tract, pancreas, esophagus, stomach, small bowel, and colon).