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

Does T2-weighted MR imaging improve preoperative detection of malignant hepatic tumors? Observer performance study in 49 surgically proven cases

The purpose of our study was to determine whether or not the addition of T2-weighted fast spin-echo (SE) imaging to gadolinium-enhanced spoiled gradient-recalled-echo (GRE) imaging improves the observer performance in the preoperative detection of malignant hepatic tumors. Gadolinium-enhanced GRE and fat-suppressed T2-weighted fast SE images obtained in 49 patients with 82 surgically confirmed malignant hepatic tumors (40 hepatocellular carcinomas and 42 metastases) were retrospectively reviewed by three independent off-site observers. In the random review of images, gadolinium-enhanced GRE images were reviewed first; thereafter, T2-weighted fast SE images were added for combined review. Observer performance was evaluated with the McNemar's test and receiver operating characteristic curve analysis. For gadolinium-enhanced GRE images alone vs. combined images, sensitivities for detection were 78% vs. 79% for hepatocellular carcinomas (P>.05), 67% vs. 71% for metastases (P<.05) and 72% vs. 75% for tumors overall (P<.05), respectively. The Az values were 0.892 vs. 0.889 in hepatocellular carcinomas (P>.05), 0.797 vs. 0.828 in metastases (P<.05) and 0.839 vs. 0.846 in tumors overall (P>.05), respectively. Our results showed that the addition of T2-weighted fast SE imaging to gadolinium-enhanced GRE imaging improved the observer performance in the detection of metastases.

Gastric cancer staging at multi-detector row CT gastrography: comparison of transverse and volumetric CT scanning

PURPOSE

To prospectively evaluate the accuracy of multi-detector row computed tomography (CT) gastrography for preoperative staging of gastric cancer, with pathologic and surgical results as the reference standard.

MATERIALS AND METHODS

This study was approved by the institutional review board, and patients gave written informed consent. One hundred six patients (72 male, 34 female; mean age, 56 years) with endoscopically proved gastric cancer underwent unenhanced and contrast material-enhanced multi-detector row CT gastrography, with effervescent granules used as oral contrast material. Two experienced radiologists independently evaluated the depth of tumor invasion into the gastric wall (tumor staging), the involvement of regional lymph nodes (nodal staging), and the presence or absence of metastasis (metastatic staging) on transverse and volumetric CT images, which included images produced with multiplanar reformation and a virtual endoscopic technique. TNM staging of each tumor was compared with the pathologic and surgical results. Diagnostic accuracy in TNM staging was analyzed.

RESULTS

Gastric cancer was detected in 92 (87%) of 106 study patients with transverse CT imaging and in 104 (98%) with volumetric CT imaging. The overall accuracy of the tumor staging was 77% with transverse CT imaging and 84% with volumetric CT imaging (P < .001). The overall accuracy for lymph node staging was 62% with transverse CT imaging and 64% with volumetric CT imaging (P = .057). For staging of metastases, there was no difference between transverse and volumetric CT imaging (86% for both) (P > .99).

CONCLUSION

Multi-detector row CT gastrography with multiplanar reformation and virtual endoscopy, compared with transverse CT imaging, can improve the accuracy of preoperative staging of gastric cancer. This difference was significant for tumor staging but not for the staging of lymph nodes and metastases.

Assessing Tumor Perfusion and Treatment Response in Rectal Cancer with Multisection CT: Initial Observations

PURPOSE

To use first-pass perfusion computed tomography (CT) to prospectively investigate tumor vascularity in rectal cancer and to determine whether any of the perfusion parameters would predict tumor response to chemotherapy and radiation therapy.

MATERIALS AND METHODS

The institutional review board approved this study, and informed prior consent was obtained from participants. Perfusion CT of rectal cancer was performed with four-section multi-detector row CT in 15 patients (13 men, two women; mean age, 62.1 years; age range, 46-84 years). Five patients with prostate cancer served as controls. All patients with rectal cancer underwent 6-8 weeks of chemotherapy and radiation therapy followed by surgery. In nine patients, perfusion CT was repeated after completion of chemotherapy and radiation therapy. Contrast medium-enhanced dynamic CT was performed with a static table position for 45 seconds, and the data were analyzed by using commercial software to calculate tissue blood flow (BF), blood volume, mean transit time (MTT), and vascular permeability-surface area product. Perfusion parameters of normal rectum and tumor were compared. Perfusion parameters before and after chemotherapy and radiation therapy were compared. A tumor was considered to have responded if its stage at pathologic analysis indicated regression compared with the preoperative stage. Baseline perfusion values were compared between responders and nonresponders. Statistical analysis was performed with the Student t test.

RESULTS

Rectal cancer showed higher BF and shorter MTT compared with those of normal rectum (P < or =.05). After chemotherapy and radiation therapy, tumors showed significant reduction in BF and increase in MTT (P < or =.05). There was a significant difference in baseline BF and MTT values between responders and nonresponders (P < or =.05). Tumors in three patients with high initial BF and short MTT showed poor response.

CONCLUSION

Perfusion CT of rectal cancer can enable assessment of tumor vascularity and perfusion changes that result from chemotherapy and radiation therapy. In this small patient sample, tumors with initial high BF and short MTT values tended to respond poorly to chemotherapy and radiation therapy.

Expression of vascular endothelial growth factor C and chemokine receptor CCR7 in gastric carcinoma and their values in predicting lymph node metastasis

AIM: To study the expression of vascular endothelial growth factor C (VEGF-C) and chemokine receptor CCR7 in gastric carcinoma and to investigate their associations with lymph node metastasis of gastric carcinoma and their values in predicting lymph node metastasis.

METHODS: The expression of VEGF-C and CCR7 in gastric carcinoma tissues obtained from 118 patients who underwent curative gastrectomy was examined by immunohistochemistry. Among these patients, 39 patients underwent multi-slice spiral CT (MSCT) examination.

RESULTS: VEGF-C and CCR7 were positively expressed in 52.5 and 53.4% of patients. VEGF-C expression was more frequently found in tumors with lymph node metastasis than those without it (P < 0.001). VEGF-C expression was also closely related to lymphatic invasion (P < 0.001), vascular invasion (P < 0.01), and TNM stage (P < 0.001). However, there was no significant correlation between VEGF-C expression and age at surgery, gender, tumor size, tumor location, Lauren classification, and depth of invasion. CCR7 expression was significantly higher in patients with lymph node metastasis compared with those without lymph node metastasis (P < 0.001) and was also associated with tumor size (P < 0.01), depth of invasion (P < 0.001), lymphatic invasion (P < 0.001), and TNM stage (P < 0.001). However, the presence of CCR7 had no correlation to age at surgery, gender, tumor location, Lauren classification, and vascular invasion. Among the 39 patients who underwent MSCT examination, only CCR7 expression was related to lymph node metastasis determined by MSCT (P < 0.05). In the current retrospective study, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of VEGF-C and CCR7 expression in the diagnosis of lymph node metastasis for patients with gastric carcinoma were 73.8%, 70.2%, 72.6%, 71.4% and 72.0%, and 82.0%, 77.2%, 79.4%, 80.0% and 79.7%, respectively. After subdivision according to the combination of VEGF-C and CCR7 expression, receiver operating characteristic (ROC) analysis showed that the accuracy of the combined examination of VEGF-C and CCR7 expression in predicting lymph node metastasis was relatively high (area under ROC curve [Az] = 0.83).

CONCLUSION: The expression of VEGF-C and CCR7 is related to lymph node metastasis of gastric carcinoma and both of them may become new targets for the treatment of gastric carcinoma. Furthermore, the combined examination of VEGF-C and CCR7 expression in endoscopic biopsy specimens may be useful in predicting lymph node metastasis of gastric carcinoma and deciding the extent of surgical lymph node resection.

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.

Preoperative simulation of vascular anatomy by three-dimensional computed tomography imaging in laparoscopic gastric cancer surgery

BACKGROUND

Treatment of early gastric cancer may be an ideal application for laparoscopic surgery. But laparoscopic surgery has various limitations derived from the lack of tactile feedback and a two-dimensional display of the operative field. So, laparoscopic surgery is technically challenging and requires a more detailed understanding of local anatomy than conventional open surgery does. The purpose of this study was to evaluate the value of three-dimensional computed tomography imaging in the preoperative simulation of laparoscopic gastric cancer surgery.

STUDY DESIGN

Multidetector-row helical CT was performed preoperatively in 49 patients who underwent laparoscopic gastric cancer surgery. Scanning was initiated approximately 20 seconds after an intravenous injection of 100 mL of contrast material at 5 mL/second. Three-dimensional CT images were reconstructed using the volume-rendering technique.

RESULTS

3D-CT imaging depicted the stomach, arterial, and venous anatomy and was able to identify important vascular variants. Preoperative information concerning the right gastric artery led us to the site of its branching and facilitated dissection of suprapyloric lymph nodes. The left gastric artery furnishing the aberrant left hepatic artery was successfully revealed and this information enabled us to avoid accidental hemorrhage and ischemic liver damage. Preoperative confirmation of the drainage routes of the left gastric vein was also useful in accomplishing secure lymphadenectomy.

CONCLUSIONS

3D-CT imaging provides a vascular "road map," which is critical for surgical guidance, and prevents the risks involved in surgery. Preoperative 3D-CT imaging may be an informative device to overcome the disadvantages of laparoscopic gastric cancer surgery.

Dedicated multidetector CT of the stomach: spectrum of diseases

Multidetector computed tomography (CT) offers new opportunities in imaging of the gastrointestinal tract. When thin collimation is used, near-isotropic imaging of the stomach is possible, allowing high-quality multiplanar reformation and three-dimensional reconstruction of gastric images. Proper distention of the stomach and optimally timed administration of intravenous contrast material are required to detect and characterize disease. In contrast to gastroscopy and double-contrast studies of the stomach, CT provides information about both the gastric wall and the extragastric extent of disease. Preoperative staging of gastric carcinoma appears to be the main clinical indication for multidetector CT. In addition, multidetector CT allows detection of other gastric malignancies (lymphoma, carcinoid tumors, metastases, gastrointestinal stromal tumors) and benign gastric tumors (neural tumors, polyps). Gastric inflammation (gastritis, ulcers, Ménétrier disease) and miscellaneous gastric conditions (emphysema, gastric outlet obstruction, varices) can also be visualized with multidetector CT. Multidetector CT is a valuable tool for the evaluation of gastric wall disease and serves as an adjunct to endoscopy.

Staging of upper GI malignancy

Imaging plays a vital role in the management of oesophageal cancer including diagnosis, staging and follow up. Computerised tomography (CT) is used for staging and follow up, with magnetic resonance imaging (MRI) having only a limited role. Endoscopic ultrasound (EUS) provides optimal information for tumour extent and local nodal involvement. Functional imaging using 2-¹⁸fluoro-deoxyglucose positron emission tomography (FDG-PET) is increasingly being used to provide unique information and, when combined with anatomic imaging, will provide better staging information for the extent of metastases and perhaps response to treatment.

Functional computed tomography in oncology

Functional Computed Tomography (CT) describes the use of existing technologies and conventional contrast agents to capture physiological parameters that reflect the vasculature within tumours and other tissues. The technique is readily incorporated into routine conventional CT examinations and, in tumours, the physiological parameters obtained provide an in-vivo marker of angiogenesis. As well as providing a research tool, functional CT has clinical applications in tumour diagnosis, staging, risk stratification and therapy monitoring, including the characterisation of pulmonary nodules, detection of occult hepatic metastases, grading of cerebral glioma and monitoring of anti-angiogenesis drugs. With the recent commercial availability of appropriate software and the development of multislice CT systems, functional CT is poised to make a significant impact upon the imaging of patients with cancer.

A surface-modified chylomicron remnant-like emulsion for percutaneous computed tomography lymphography: synthesis and preliminary imaging findings

RATIONALE AND OBJECTIVES

To assess a surface-modified emulsion as a percutaneous CT lymphographic agent in normal dogs.

METHODS

An iodinated chylomicron remnant-like microemulsion was formulated with a mean particle size of 91.3 nm and an iodine concentration of 91 mg I/mL. Contrast material (2 mL) was injected into the subcutaneous tissues of the metatarsus and metacarpus of six normal dogs to enhance popliteal and cervical lymph nodes, respectively. CT images were acquired at 0, 15, 30, 45, 60, 240, 480, and 1440 minutes.

RESULTS

Significant lymph node enhancement occurred in as little as 15 minutes after injection and persisted at least 8 hours. Node opacification was most pronounced at 1 to 4 hours postinjection and exceeded 200 HU in some nodes (precontrast attenuation = 45 HU). Marked enhancement of popliteal efferent lymphatics and of iliac and sacral node groups also occurred indicating distribution to second order nodes. Attenuation of enhanced nodes reverted to precontrast levels by 24 hours.

CONCLUSION

The new surface-modified, chylomicron remnant-like emulsion provided marked, selective enhancement of targeted lymph nodes after subcutaneous administration. Moreover, the formulation produced significant opacification of more distant node groups from a single injection.

Provision of MRI can significantly reduce CT collective dose

The purpose of this study was to investigate the proportion of patients currently being investigated by CT that could be investigated by MRI with a potential reduction in exposure to ionizing radiation. The health detriment arising from the radiation dose associated with CT has been quantified in terms of the number of likely cases of serious health effects. The results show that a significant saving in the collective radiation dose is possible, with an associated detriment of between 0.23 and 0.33 cases of cancer or severe hereditary effects averted in one imaging department every year. In selecting the balance of provision of MRI and CT facilities, the health detriment associated with the radiation dose from CT should be considered.

Two cases of histopathologically advanced (stage IV) early gastric cancers

We report two cases of early gastric cancer with distant metastases (stage IV). At our institute 1428 cases of primary gastric cancer were resected between 1980 and 1997; 536 were diagnosed as early gastric cancer based on the resected specimens (304 cases of mucosal cancer, Tis--TNM classification--and 232 of submucosal cancer, T1). 528 of these 536 cases were classified as histological stage I, six as stage II, none as stage III and two as stage IV. The incidence of stage IV early gastric cancer was 0.14% of all gastric cancers and 0.37% of the early gastric cancers. The two patients with stage IV early gastric cancer were women. Both tumors were defined as early cancer because they were confined to the submucosa. One was a type 0 IIc + III early cancer, histologically classifiable as a small, moderately differentiated adenocarcinoma (tub2 according to the Japanese Classification of Gastric Carcinoma, G2; TNM classification: ICD-O C16), size 10 x 8 mm; the other was a surface spreading type 0 IIc, classifiable as a signet-ring cell carcinoma (sig, G3), size 50 x 35 mm. Stage IV factors were N3 in the first and ovarian metastasis (Krukenberg tumor) in the second case.

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).

Time trends of surgical treatment and the prognosis for Japanese patients with gastric cancer

The incidence of gastric cancer is much higher in Japan than in other countries even though diagnostics and treatments of such patients have improved. The objective of this study was to present an overview of the past, present and future of surgical treatment for our patients with gastric cancer. We analysed data on 2152 Japanese men and women with gastric cancer who underwent surgical resection from 1965 to 1995 at Kyushu University in Fukuoka, Japan, based on a univariate and the multivariate analysis. We focused on time trends of surgical treatment and the postoperative outcome. Over the years, there have been favourable changes in the numbers of patients with early gastric cancer. In all cases of gastric cancer, the rate of 18% in the first six year period (group 1) was 57% in the last 5 year period (group 6). Size of the tumour was smaller, well-differentiated tumour tissue was more common, and lymphatic involvement was less frequent. Lymph node metastasis, liver metastasis and peritoneal dissemination all decreased. Extensive lymph node dissection was more frequently done and the rate of curative resection (curability A and B) increased. With increases in identifying the early stage of cancer and better perioperative care, mortality rates 30 days after the surgery greatly decreased. Multivariate analysis revealed that the 10 factors of depth of invasion, lymph node metastasis, lymph node dissection, tumour size, liver metastasis, peritoneal dissemination, lymphatic invasion, vascular invasion, lesion in the whole stomach and lesion in the middle stomach were independent factors for determining the prognosis. Detection of the tumour in an early stage, standardized surgical treatment, including routine lymph node dissection, close follow-up schedules and better perioperative management are expected to increase survival time for patients with this malignancy.

Comparison of dynamic helical CT and dynamic MR imaging in the evaluation of pelvic lymph nodes in cervical carcinoma

OBJECTIVE

This study compares dynamic helical CT with dynamic MR imaging in the evaluation of pelvic lymph nodes in cervical carcinoma.

SUBJECTS AND METHODS

Women with biopsy-proven cervical carcinoma prospectively underwent dynamic helical CT and MR imaging before surgery. A metastatic node on CT and MR imaging was defined as a rounded soft-tissue structure greater than 10 mm in maximal axial diameter or a node with central necrosis. Imaging results were compared with pathology, and receiver operating characteristic curves for size and shape were plotted on a hemipelvis basis. Nodal density and signal intensity on CT and MR images, respectively, were reviewed for differences between benign and malignant disease.

RESULTS

A total of 949 lymph nodes were found at pathology in 76 hemipelves in 43 women, of which 69 lymph nodes (7%) in 17 hemipelves (22%) were metastatic. Sensitivity, specificity, positive and negative predictive values, and accuracy of helical CT and MR imaging in the diagnosis of lymph node metastasis on a hemipelvis basis was 64.7%, 96.6%, 84.6%, 90.5%, and 89.5% and 70.6%, 89.8%, 66. 7%, 91.4%, and 85.5%, respectively. Receiver operating characteristic curves for helical CT and MR imaging gave cutoff values of 9 and 12 mm in maximal axial diameter, respectively, in the prediction of metastasis. Central necrosis had a positive predictive value of 100% in the diagnosis of metastasis. Signal intensity on MR imaging and density-enhancement pattern on CT in patients with metastatic nodes did not differ from those in patients with negative nodes.

CONCLUSION

Helical CT and MR imaging show similar accuracy in the evaluation of pelvic lymph nodes in patients with cervical carcinoma. Central necrosis is useful in the diagnosis of metastasis in pelvic lymph nodes in cervical cancer.

Cystic dystrophy of the duodenal wall in the heterotopic pancreas: radiopathological correlations

PURPOSE

The purpose of this work was to correlate the CT features of cystic dystrophy in heterotopic pancreas (CDHP) with pathological features.

METHODS

Patients were selected from 190 patients who underwent pancreatico-duodenectomy over a 10 year period in our institution. CT findings were retrospectively analyzed in 20 cases and correlated with pathological findings.

RESULTS

Lesions were found to be located in the inner part of the second portion of the duodenum in all except one case. In all cases, the duodenal wall was thickened, both at CT and at histopathological examination, and moderate to strong contrast enhancement of the duodenal wall was noted at CT in all cases but one. Cysts were multiple in all cases. No heterotopic pancreas was identified with CT. Inflammatory changes with or without enlarged nodes were detected on CT in 15 of 20 cases. Chronic pancreatitis was present in 10 cases at pathology, including 5 cases with calcifications. The radiopathological correlation was excellent for all criteria but two: the size of the cysts and the extent of pyloric involvement.

CONCLUSION

In patients with CDHP, CT features correlate well with pathological results. Multiple cysts located in an enlarged duodenal wall with postcontrast enhancement and inflammatory changes are strongly suggestive of CDHP.

MRI in staging advanced gastric cancer: is it useful compared with spiral CT?

PURPOSE

During the last decade, rapid progress has been made in MR technology. Our objective was to evaluate the role of MRI in staging advanced gastric cancer (AGC; gastric cancer invading the muscularis propria) and to compare it with that of spiral CT.

METHOD

We prospectively performed both MR and CT examinations on 26 patients with AGC proven by endoscopic biopsy. Contrast-enhanced CT and nonenhanced MRI with a 1.0 T scanner using FLASH, HASTE, and true-FISP sequences were obtained in each patient after injection of antiperistaltic drug and ingestion of 1 L of tap water. Fifty-two sets of CT and MR images were analyzed by two radiologists in consensus without any information from other images. T and N staging of AGC was determined according to the TNM classification. All patients underwent surgery within 1 week after both examinations. Diagnostic accuracy of each staging of AGC on CT or MRI was evaluated by comparison with the pathologic results.

RESULTS

MRI was slightly superior to CT in T staging (81 vs. 73%, respectively; p < 0.05). Although MRI had a tendency to overstage the pathologic T2 cancer, positive predictability of T2 stage and sensitivity of T3 stage were high (100%, respectively). Regarding the N staging, CT was slightly superior to MRI (73 vs. 65%; p > 0.05). However, both CT and MRI demonstrated the tendency of understaging in N staging.

CONCLUSION

Although MRI was superior to spiral CT in T staging, MRI cannot completely replace spiral CT in staging AGC because of its limitation in N staging.

Helical hydro-CT for diagnosis and staging of gastric carcinoma

PURPOSE

The purpose of this work was to define the accuracy of helical hydro-CT (HHCT) in the diagnosis and staging of gastric carcinoma.

METHOD

One hundred twelve patients with gastric carcinoma were preoperatively imaged by HHCT. Gastric distension was achieved by ingestion of up to 1,500 ml of water. Bolus tracking was performed, and peristalsis was minimized by intravenously administered spasmolytics. Contrast material was then injected, and helical scanning was performed at the time of peak enhancement of the liver. CT images were analyzed for tumor infiltration of the gastric wall, and TNM staging criteria were applied according to the International Union Against Cancer (UICC) classification. The results were correlated with histopathologic findings.

RESULTS

One hundred two of 115 (89%) gastric carcinomas were correctly diagnosed by HHCT. Small malignant ulcers (< or =2 cm) that corresponded to early gastric carcinoma were not visible on CT scans. T and N staging accuracies were 51% each; abdominal M staging was correct in 79% of all cases. The positive and negative predictive values of HHCT to foresee curative resection of gastric carcinoma were 75 and 84%, respectively.

CONCLUSION

Mural thickening as well as marked contrast enhancement of the gastric wall are firmly related to gastric carcinoma. The accuracy of HHCT is acceptable for M staging but inadequate for local staging of gastric carcinoma. Nonetheless, HHCT is a useful guide for choosing between tumor resection and nonoperative treatment of patients. We therefore recommend HHCT as the method of choice for preoperative imaging of gastric carcinoma.

Imaging diagnosis for staging of gastric cancer

A more differentiated therapy regimen concept for gastric cancer requires more precise pre-operative diagnostic imaging. There are several methods for pre-operative locoregional tumor staging in gastric cancer: percutaneous abdominal ultrasound with hydrotechnique (HUS), endoluminal ultrasound in the stomach (EUS), computed tomography (CT), and magnetic resonance imaging (MRI). The advantages and indications for each method are described and an overview of the medical literature is given. The results in the literature are compared to our own findings, which were obtained in prospective studies comparing the four different imaging methods. On the basis of our experience and the literature, we conclude that the indication for the different diagnostic imaging methods primarily depends on the type of therapy concept followed in the respective surgical department. Endoscopy with biopsy remains the primary diagnostic procedure. Endosonography (EUS) is another diagnostic procedure, which can be performed simultaneously with endoscopy. Only special questions or reasons warrant the use of other imaging methods.

Tumour angiogenesis and its relation to contrast enhancement on computed tomography: a review

Angiogenesis describes the formation of new blood vessels within tumours. The process is essential for tumour growth and metastasis. The development of new vessels leads to physiological changes, specifically increased perfusion, blood volume and capillary permeability, that alter contrast enhancement during computed tomography (CT). Functional CT techniques that quantify these physiological changes can provide greater insight into how angiogenesis alters contrast enhancement in routine practice and also serve as diagnostic tools in their own right. The functional information obtained can aid with tissue characterisation, such as type or grade of tumour, improve the detection of hepatic metastases, produce clearer delineation of tumours with benefits for radiotherapy planning and biopsy, and provide prognostic information. By providing a marker for tumour angiogenesis, quantitative contrast enhanced CT can improve the diagnostic assessment of patients with cancer.

Metastases to pelvic lymph nodes from carcinoma in the pelvic cavity: diagnosis using thin-section CT

OBJECTIVE

To assess the accuracy of thin-section computed tomography (CT) in the diagnosis of pelvic lymph nodes affected by metastatic cancer.

METHODS

Incremental CT was performed by obtaining 3 mm sections with 3 mm intervals in 34 patients who had carcinoma in the pelvis, pre-operatively and prospectively. CT diagnoses were made before surgery using the cine mode with a manual trackball. Lymph nodes with a maximum short axis diameter of greater than 5 mm were considered enlarged.

RESULTS

The accuracy, sensitivity, specificity, positive and negative predictive values of CT diagnoses were 79.7%, 54.5%, 84.9%, 42.9% and 90.0% on a hemipelvis basis; and 79.4%, 85.7%, 77.8%, 50.0% and 95.5% on a patient basis, respectively. There was only one false-negative case on a patient basis analysis.

CONCLUSION

Because of a fairly high negative predictive value, negative thin-section CT can be considered an alternative to surgical lymphadenectomy. This is clinically important as unnecessary staging operations and extended surgery are avoided.

Low sensitivity of computed tomography in the staging of gastric lymphomas of mucosa-associated lymphoid tissue: impact on prospective trials and ordinary clinical practice

The natural history and management of gastric lymphomas of mucosa-associated lymphoid tissue (MALTomas) are not completely understood. Most stage I cases are now entered into prospective trials to confirm the excellent results obtained with conservative treatment, whereas current therapeutic policies are based on accumulated experience. The limits of staging work-ups may have a significant impact on prospective trials and ordinary clinical practice. The authors explore the sensitivity of computed tomography scanning in detecting perigastric adenopathy in 20 patients with gastric MALToma treated by gastrectomy. Clinical staging identified 17 patients as having stage I MALTomas and three patients as having stage II1 MALTomas. Histopathologic staging showed that 8 of 17 patients formerly diagnosed with stage I MALToma had perigastric nodal involvement, whereas the three patients with clinical stage II1 were confirmed as such. Computed tomography scanning has low sensitivity in detecting perigastric lymphadenopathy in gastric MALTomas. This leads to understaging, with a significant impact on therapeutic decision, and distorts newly acquired knowledge about the disease's natural history and management, introducing a bias in prospective clinical trials. Endoscopic ultrasonography should be tested as a staging procedure both in prospective trials and in ordinary clinical practice.

Usefulness of the non-distension of the stomach in the evaluation of perigastric invasion in advanced gastric cancer by CT

The purpose of this study was to evaluate by CT the usefulness of the non-distension of the stomach in determining invasion of the gastric cancer into perigastric space and adjacent organs. Forty-eight patients with pathologically proved gastric cancer were studied by conventional CT. Patients were examined using two techniques: (a) non-distension of the stomach in the supine position and 34 patients additionally in prone position; and (b) distension of the stomach with water or air in the supine and/or prone position. CT findings by both techniques were separately analysed preoperatively and compared to surgical findings. Invasion of perigastric fat was better demonstrated by the non-distension technique in 15 of the 36 patients with pathologically proven fat infiltration. Non-distension technique was more accurate than distension in detecting: (a) involvement of gastric ligaments (80 versus 67% for gastrohepatic, 85 versus 73% for gastrocolic and 80% by both techniques for gastrosplenic ligament); (b) perigastric lymphadenopathy (86% by both techniques for lymph nodes sited at the gastrohepatic ligament, 85 versus 75% for gastrocolic and 85 versus 80% for gastrosplenic ligament lymph nodes, respectively); and (c) pancreatic invasion (86 versus 80%). The prone position with non-distended stomach was particularly helpful in excluding pancreatic invasion in five patients with carcinoma of the gastric body. The distension technique was more accurate in demonstrating perigastric extension in gastroesophageal junction tumors in two patients. In conclusion, additional CT of the non-distended stomach with the patient in prone position can provide further evidence about infiltration of the perigastric fat, ligaments, lymph nodes and pancreas, in patients with gastric carcinoma, with the exception of gastroesophageal junction tumors.

Correlation of CT with histopathological findings in patients with gastric and gastro-oesophageal carcinomas following neoadjuvant chemotherapy

Gastric carcinoma is the fourth commonest cause of death from malignant disease in United Kingdom. In the Western hemisphere, it usually presents with advanced disease, which contributes to its very poor prognosis. Pre-operative (neoadjuvant) chemotherapy offers the possibility of down-staging such tumours and the potential to render tumours operable. Computed tomography (CT) plays a central role in the assessment of patients presenting with the disease, and in those who undergo chemotherapy, in evaluating their response.

OBJECTIVE

This study was undertaken to evaluate the role of CT in predicting loco-regional spread of tumour following neoadjuvant chemotherapy in non-metastatic gastric and gastro-oesophageal cancers.

METHODS AND MATERIALS

We correlated CT evidence of loco-regional spread with pathological findings following surgery in 21 patients who received pre-operative chemotherapy.

RESULTS

Residual masses were seen on CT in 19 patients, and 15 contained active tumour, although in four patients no viable tumour was demonstrated at histopathology. The overall accuracy of CT in assessing loco-regional disease was disappointing with sensitivities, specificities, positive and negative predictive values of 57%, 43%, 75% and 33%, respectively.

CONCLUSIONS

We conclude that CT is not accurate in identifying residual loco-regional spread and therefore should not preclude surgery in those patients who have received neoadjuvant chemotherapy.

Relationship between histological type and endosonographic detection of regional lymph node metastases in gastric cancer

The aim of the study was to compare the ability of endoscopic ultrasonography (EUS) in detecting lymph node metastases in differentiated and undifferentiated gastric adenocarcinoma. EUS was performed in 149 patients with differentiated or undifferentiated gastric cancer. Histopathological findings were compared with pre-operative EUS findings in a total of 2961 resected lymph nodes. The EUS detection rates of metastasis to individual nodes in relation to node size, the ratio of the metastasized area to the cross-sectional area of the node and to the depth of primary tumour invasion, were also investigated. The accuracy and negative predictive values of EUS for detecting metastatic lymphadenopathy in each patient were significantly higher for differentiated (87%, 94%) than for undifferentiated (71%, 71%) tumours. The detection rate of individual node metastasis was higher for differentiated (31%) than for undifferentiated (21%) tumours. For differentiated lesions, EUS detected more small nodal metastases (< 5 mm in diameter) (p < 0.01) and more nodes involved with a relatively small proportion of the metastasized area to the cross-sectional area of the node (< 1/3 involvement) (p < 0.05). In relatively superficial lesions, such as pT1 and pT2, the pre-operative EUS detection rate of metastatic nodes was higher for differentiated than for undifferentiated tumours. In conclusion, the ability of EUS to detect nodal metastases is related to the histological type of gastric cancer.

Efficacy of helical CT in T-staging of gastric cancer

PURPOSE

The purpose of this study was to evaluate the performance of helical CT in preoperative T-staging in patients with gastric cancer.

METHOD

A total of 71 patients with an established diagnosis of gastric cancer [75 lesions, 46 early (T1) and 29 advanced (T2 or more) cancers] were evaluated with helical CT. Helical CT was performed with 5-mm slice thickness at 5-mm/s table incrementation. Using the volumetric data by helical scanning, axial CT images (5-mm slice thickness at 5-mm intervals) and multiplanar reconstruction (MPR) images were obtained. CT findings were compared with histopathologic studies of the resected specimen.

RESULTS

Sensitivity of helical CT for gastric cancer was 26% (12 of 46) for early and 100% (29 of 29) for advanced cancer. Three lesions were misdiagnosed as gastric cancer by helical CT. Histopathologically, all early gastric cancers detected by helical CT were either polypoid or elevated types or showed massive invasion of the submucosal layer. The differentiation between T1 cancer with massive submucosal invasion and advanced cancer was difficult. The differentiation between T2 and T3 cancer was possible in 73% (19 of 26) and between T1/T2 and T3/T4 (extraserosal invasion) in 83% (34 of 41). Overall T-staging was correct in 66% (27 of 41). MPR images improved the detection rate (three lesions) or increased confidence in T-staging (eight lesions) over axial CT images.

CONCLUSION

When helical CT detected gastric cancer that was not a polypoid or elevated type with underlying normal-appearing gastric wall, it was either T1 cancer with massive invasion of the cancer cells into the submucosal layer or advanced cancer. However, differentiation between these two stages was difficult on CT. Diagnosis of serosal invasion was not markedly improved by helical CT. MPR images increased confidence in the staging of certain gastric cancers, such as those in locations where CT images are susceptible to partial volume averaging effects.

CT measurements of capillary permeability within nodal masses: a potential technique for assessing the activity of lymphoma

Analysis of time-attenuation data has enabled CT to measure capillary permeability within the brain and kidney. As yet, such techniques have not been applied to nodal masses in patients with lymphoma. Tumour angiogenesis is known to produce capillaries that exhibit increased permeability and CT measurements of permeability could therefore potentially provide a marker of tumour viability. This study aims to determine the feasibility and limitations of CT measurement of capillary permeability within lymphoma nodal masses. Six patients with biopsy proven lymphoma have been studied. Time-attenuation curves from the aorta and nodal mass were generated from a single-location dynamic sequence of images acquired over 3 min following an intravenous bolus of iopamidol. A nuclear medicine data processing technique, Patlak analysis, was used to calculate capillary permeability and blood volume within the nodal mass. Renal blood vessel permeability was also determined in four patients. Median lymph node permeability to iopamidol was 88.5 microliters min-1 ml-1 (range 36.4-198.5 microliters min-1 ml-1). The correlation coefficient of the linear fit for the Patlak analysis ranged from 0.74 to 0.95 and was greater than 0.9 for regions of interest of 150 pixels or more (256 x 256 matrix). The values for renal permeability (442 microliters min-1 ml-1; range: 349-589 microliters min-1 ml-1) were comparable to those previously reported. Functional images of permeability were also obtained. The study has confirmed the feasibility of CT measurements of capillary permeability within nodal masses. The technique combines anatomical imaging and functional information within one examination and has potential application in monitoring the response of lymphoma to therapy.