Gastric cancer by multidetector row CT: preoperative staging

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

Elevated gastric lesions: virtual gastroscopy

With the development of multidetector computed tomography and the improvement in the capabilities of workstations, the use of high-quality three-dimensional reconstructions and virtual images can be applied to organs other than the colon such as the stomach. As a noninvasive technique, virtual gastroscopy represents an alternative to conventional endoscopy for the detection of elevated lesions. Findings of this technique are illustrated.     

多层CT虚拟胃镜显示胃癌:与光学胃镜和病理结果对照

目的 探讨多层CT虚拟胃镜(VG)与轴位图像对胃癌检出的价值,并与光学胃镜和病理对照。方法 对连续67例经光学胃镜活检证实或高度怀疑胃癌的患者,在服产气粉充分扩张胃后行多层螺旋CT薄层扫描后行VG。由2名放射诊断医师在不知光学胃镜结果的情况下分别评估VG和CT轴位图像,并通过协商达成一致。评价结果与光学胃镜和手术切除大体标本比较,采用McNemar检验比较VG图像和CT平扫轴位图像对胃癌灶的检出率。结果 67例患者中,VG检出61例,获得与光学胃镜相似图像,并经大体标本证实,其检出率(61/67,91.04%)与轴位CT的检出率(56/67,83.58%)差异无统计学意义(P=0.227)。对于胃癌灶≤3 cm的23例患者,VG检出20例(20/23,86.96%),高于轴位图像的13例(13/23,56.52%,P=0.016)。结论 采用MSCT行VG能检出胃癌,可获得与光学胃镜相似的图像;检出小胃癌病灶优于轴位CT,有望成为检出胃癌的辅助手段。     

CT's capability in detecting advanced gastric cancer

Upper GI series and CT scans of 23 patients with advanced gastric cancer were reviewed and correlated to determine CT's capability in detecting gastric tumors. The CT images of the gastric carcinomas revealed either a mass or thickening of the wall. These abnormalities were present in 78% of the cases whereas CT demonstrated a mass in 52%. The most difficult site for CT diagnosis of gastric cancer was the antrum. Diagnostic accuracy of CT in evaluating tumor invasion of adjacent structures is reportedly high. However, in the present study this was not necesarily true. In 4 of 5 patients whose gastric tumors proved unresectable, CT failed to reveal adjacent invasion. This suggests that CT is not always reliable in predicting surgical resectability.     

Afferent loop obstruction after gastric cancer surgery: helical CT findings

Background: We reviewed the computed tomographic (CT) findings of afferent loop obstruction and assessed the value of helical CT in determining the underlying cause.Methods: Helical CT scans of 18 patients (12 men and six women; age range = 35–67, mean age = 50 years) with afferent loop obstruction were reviewed. All patients had gastric cancer. Ten patients had undergone radical subtotal gastrectomy with Billroth II gastrojejunostomy, and eight had undergone total gastrectomy with Roux-en-Y esophagojejunostomy. CT images were analyzed retrospectively, and the presumed cause of obstruction on CT was compared with surgical findings (n = 8) and clinical courses (n = 10).Results: Local recurrence (n = 15), peritoneal seeding (n = 1), internal hernia (n = 1), and adhesion (n = 1) were the presumed causes of obstruction on CT. In all eight patients who underwent a second operation, the cause of afferent loop obstruction was correctly suggested on CT (local recurrence in six patients and adhesion and internal hernia in one patient). In 10 patients who were not re-explored, the clinical findings or biopsy indicated recurrent tumor as suggested on CT.Conclusion: Recurrent tumors and other potential causes of afferent loop obstruction can be correctly predicted with CT in most cases.     

Resectability of pancreatic adenocarcinoma: assessment using multidetector-row computed tomography with multiplanar reformations

The purpose was to assess capabilities of the multidetector-row computed tomography (MDCT) with multiplanar reformations (MPR) for predicting of pancreatic adenocarcinoma resectability. Forty-eight patients deemed to have resectable pancreatic adenocarcinoma after assessment using biphasic MDCT with MPRs underwent surgery for potential tumor resection. Imaging findings were retrospectively evaluated for tumor resectability and correlated with surgical and pathological results. Curative resection was successful in 44 of 48 patients. The positive predictive value for tumor resectability made up 91% with four false-negative results. The reasons for unresectability were venous involvement (1), small liver metastases (2) and peritoneal involvement associated with small metastases to lymph nodes (1). MDCT yielded a negative predictive value of 99% (286 of 288 vessels) for detection of vascular invasion. Our results indicate the tendency towards improved prediction of resectability using MDCT compared to single-detector CT.     

CT virtual pancreatoscopy: a new method for diagnosing intraductal papillary mucinous neoplasm (IPMN) of the pancreas

Background We sought to validate computed tomographic virtual pancreatoscopy (CT-VP) created by multidetector row CT (MD-CT) in the clinical diagnosis of intraductal papillary mucinous neoplasm (IPMN) of the pancreas. Methods Five cases of pancreatic IPMNs were included in this study. A nasopancreatic drainage tube was inserted and the pancreatic duct was filled with contrast medium, after which an upper abdominal scan was performed by MD-CT. CT-VP and three-dimensional (3D) CT pancreatographic images were created using a workstation and compared with images by conventional diagnostic techniques. All cases were evaluated by endoscopic retrograde pancreatography (ERP) and three cases of main duct type were assessed by intraoperative real pancreatoscopy (RP). Results In the main duct cases, papillary projections in the main pancreatic duct and branch orifices were clearly detected by CT-VP. These lesions and structures were confirmed by intraoperative RP, and the CT-VP images were clearer than RP images. In branch cases, a surface-rendering method allowed protruding lesions to be clearly detected in the dilated branches. Conclusion Compared with conventional ERP or RP, CT-VP and 3D-CT pancreatographic images were finer in quality, and the procedures were less invasive, faster, and less expensive. The potential shown by CT-VP with 3D-CT pancreatography in the clinical diagnosis of pancreatic IPMNs suggests that this approach may replace ERP in the near future.     

Calcified gastric carcinoma: CT findings

The computed tomographic (CT) findings of 13 cases of calcified gastric carcinoma were analyzed retrospectively. Eleven cases were confirmed as a mucinous adenocarcinoma by surgery (three cases), or endoscopic biopsy (eight cases). Two cases were diagnosed as adenocarcinoma by endoscopic biopsy. In all cases the calcifications were of the punctate or miliary shape and the size varied from 1–3 mm in diameter. The calcifications were located in the thickened gastric wall in all cases, and were seen in metastatic lesions such as lymph nodes and the liver in two cases. In 10 cases, some tumor portions showed lower attenuation number than that of the muscle on CT scans, and corresponded to mucin pool in tumor portions histologically. Twelve cases were in inoperable advanced stage.     

Acute gastrointestinal bleeding: contrast-enhanced MDCT

With the introduction of multidetector row computed tomography (MDCT), CT is being considered a potential diagnostic method for patients with acute gastrointestinal (GI) bleeding. On arterial phase MDCT images, active GI bleeding is typically identified as a focal area of high attenuation within the bowel lumen, which represents a collection of contrast material that has been extravasated in association with arterial bleeding. Additional CT findings suggestive of acute GI bleeding are focal dilatation of fluid-filled bowel segment noted on contrast-enhanced CT and acute hematoma on unenhanced CT. In addition to detection of active bleeding, an advantage of contrast-enhanced MDCT is the ability to demonstrate morphologic changes in the GI tract, which could suggest specific conditions that cause acute GI bleeding such as intestinal tumors. Arterial phase contrast-enhanced MDCT is rapid, noninvasive, and accurate in detecting and localizing sites of bleeding in patients with acute GI bleeding. Contrast-enhanced MDCT may be a promising diagnostic option in patients with acute GI bleeding.     

Acute appendicitis within a femoral hernia: multidetector CT findings

We present a case of surgically proved acute appendicitis strangulated in a femoral hernia sac. Multidetector computed tomography with multiplanar reformations was thought to be helpful in evaluating acute appendicitis in a femoral hernia sac. An awareness of computed tomographic findings may avoid a delay in recognition and management of a patient with this unusual condition.     

Multidetector CT colonoscopy: evaluation of the perspective-filet view virtual colon dissection technique for the detection of elevated lesions

Background The purpose of our study was to determine the usefulness of a virtual computed tomography colon dissection visualization technique for the detection of polypoid lesions in comparison with conventional virtual colonoscopy analysis and optical colonoscopy. Methods Twenty-three patients were evaluated with optical colonoscopy and computed tomography colonoscopy using 16-row MDCT on the same day. CT images were analyzed by the colon dissection workup with unfolded haustra visualization and also using the conventional virtual colonoscopy technique (axial images and endoluminal views). The CT analysis was performed by an experienced radiologist using both viewing methods in a randomized order and blinded to optical colonoscopy results. Results Optical colonoscopy revealed 35 colonic lesions; 15 < 5 mm, 18 between 5–9 mm and 2 > 9 mm. For conventional virtual colonoscopy analysis the overall sensitivity was 86.67%; for the colon dissection visualization technique, the overall sensitivity was 82.86%. The average reading time for conventional virtual colonoscopy was 15 ± 3 vs. 8 ± 2 min for the colon dissection visualization technique. Conclusions Our results showed that there is a significant reduction in the reading time using the colon dissection visualization technique without detriment to the detection rate, that is, competitive to conventional virtual colonoscopy interpretation results. There are no conflicts of interest in connection with the submitted article.     

CT virtual endoscopy of the stomach: comparison study with gastric fiberscopy

Background We evaluated the value of computed tomographic (CT) gastric virtual endoscopy (VE) by comparing it with real gastric fiberscopy (GF).Methods Sixty-six VE findings in 63 patients were compared with lesions found with GF. After a GF examination, the examinees were given bubble-making granules for the stomach and placed in a supine position on the CT table. Abdominal CT slices of 1 mm thickness were obtained by multidetector row CT (Siemens Sensation 16) and reconstructed to VE images with volume and surface rendering on the same day.Results VE images were successful in showing subtle alterations in the gastric mucosal folds. Gastric cancer, polyps, ulcers, erosions, and gastritis were clearly visualized. Comparison studies between VE and GF (as the gold standard) showed a sensitivity of 92.7% and a specificity of 90.9%. Original CT images were also useful in detecting lesions in other abdominal organs such as the liver, adrenal gland, and kidney.Conclusion Because VE is a good noninvasive screening method, except for minimal radiation exposure, it is expected to become a new technique for stomach examinations.     

Computed tomography of gastric lipomas

The computed tomographic manifestations of 2 cases of benign gastric lipoma are reported. Although conventional barium studies revealed the usual nonspecific appearances of submucosal tumors, their true fatty nature was easily demonstrated by computed tomography (CT). CT is a highly reliable noninvasive method for the diagnosis of gastric lipoma.     

Computed tomography in the preoperative evaluation of gastric carcinoma

Computed tomography (CT) of the abdomen was done in 49 patients with gastric carcinoma. These cases were retrospectively staged and evaluated as to operability. Various staging parameters were also evaluated separately. The results were correlated to findings on surgery, liver scan, and cytology. Overall accuracy of CT staging and operability assessment was 72 and 82%, respectively. Among the various CT parameters, perigastric fat invasion had a positive predictive value of 91%. The demonstration of local node involvement and invasion of adjacent organs was unreliable. Since surgery is currently the only treatment for gastric carcinoma, CT staging has limited clinical value. The principal role of CT is in the assessment of operability in patients with carcinoma of the stomach.     

Computed tomography of the abdomen: Initial experience

Computed tomography has provided a new dimension in the roentgenologic evaluation of the abdomen. Normal structures not visible on conventional examinations are clearly identified. Abnormalities are recognized by their alterations in anatomic form or by their effect on tissue absorption values. Our early experience suggests that in the abdomen computed tomography will be most valuable in detecting lesions in those sites least accessible to conventional roentgenographic methods such as the liver, spleen, pancreas and retroperitoneum.     

CT staging of early rectal carcinoma

Of 43 rectal carcinomas, initially presumed to be modified Dukes' stage A or B-1, 42 were examined with computed tomography (CT) prior to endocavitary treatment or surgery in 40 cases. The CT correctly showed 28 patients to have early stages and incorrectly showed 2 to have perirectal extension. Three patients had anal neoplasms. The remaining 10 patients had disease stage B-2 or higher and CT was not good for staging them. A CT scan can fairly accurately stage rectal carcinomas stage A and B-l grouped together, and is doing better in predicting the prognosis than digital palpation when histologic sections show well or moderately well-differentiated adenocarcinoma of the rectum.     

Intragastric metastasis in a patient with gastric cancer: unusual CT manifestation

We describe computed tomographic findings of intragastric metastasis in a patient with gastric cancer. On computed tomography, the intragastric metastatic lesion appeared as an exophytically growing cystic masss with minimal thickening of the adjacent gastric wall, thus mimicking an exophytically growing submucosal tumor or adenocarcinoma. Received: 18 May 2001/Revision accepted: 10 October 2001     

18F-FDG PET/CT显像在胃癌术后复发和转移中的诊断价值

目的：探讨18F-FDG PET/CT显像在胃癌术后复发及转移灶诊断中的价值。方法：胃癌术后患者112例,共行PET/CT检查150例次,图像分析采用视觉及半定量分析法（SUVave）,病灶根据病理学检查结果、多种影像学检查手段及临床随访确诊,随访时间半年以上。结果：112例患者中,16例存在肿瘤复发和转移,PET/CT诊断残胃复发的灵敏度为81.2%,特异性100%,准确性97.3%。复发病灶SUVave为4.4±1.2,吻合口炎性病灶SUVave为2.6±0.5,两者差异显著（t=3.9370,P=0.0005）。PET/CT诊断胃癌术后肿瘤转移的灵敏度94.1%、特异性96.7%和准确性95.5%。26例行两次以上PET/CT检查,第一次PET/CT检查发现复发或转移15例,经放化疗后6例PET显像示病情好转,随访6个月至2年患者均存活;9例治疗后PET显像示病情无明显变化或者出现新病灶,患者存活时间为3个月至1年。结论：18F-FDG PET/CT在胃癌术后复发和转移中有很好的诊断价值,并在监测胃癌术后复发放化疗疗效有一定的价值。