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 18F-FDG 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 18F-FDG PET scanning for their preoperative evaluation. The sensitivities, specificities and accuracies of CT and 18F-FDG 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 18F-FDG PET imaging for detecting peritoneal metastasis. RESULTS: Based on the original preoperative reports, CT and 18F-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 (κ value = 0.684) for CT and moderate (κ 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.

Peritoneal Lymphomatosis: Case Report

Peritoneal lymphomatosis is a rare manifestation of high grade lymphomas. Although it is difficult to differentiate peritoneal lymphomatosis from other peritoneal diseases such as peritoneal carcinomatosis and leiomyomatosis clinically and radiologically, it should be included in differential diagnosis because the disease is curable with chemotherapy. Consequently, radiologic diagnosis plays a very important role in the detection of this disease. We experienced two cases of peritoneal lymphomatosis with primary gastrointestinal lymphomas in the distal ileum. The two patients were 25 and 50-year-old males. Abdominal CT, ultrasound and barium study were performed on both patients. Both patients had non-Hodgkin's lymphoma confirmed with open or sonographically guided biopsies. Although radiologic appearances overlapped, characteristic findings of long-segmental circumscribed annular mass, aneurysmal luminal dilatation, small to moderate amount of ascites without septation or loculation, diffuse involvement of mesentery, omentum and peritoneum, and enlarged lymph nodes were helpful in narrowing the range of possible diagnoses.

Efficacy of Spiral CT in the Evaluation of Peritoneal Seeding of Gastric Cancer

PURPOSE: To determine usefulness of spiral CT in the preoperative evaluation of peritoneal seeding from a gastric carcinoma. MATERIALS AND METHODS: From a database of 411 consecutive patients with surgically proven advanced gastric cancinoma obtained over a six-month period, 17 with peritoneal seeding and a control group of 24 without peritoneal seeding underwent spiral CT scanning with 7 -8 mm scan thickness and interval during the portal phase. Preoperative CT images were analyzed by two readers who reached a consensus with regard to the presence and location of the ascites, thickening of the parietal peritoneum, and changes in the omentum and mesentery. RESULTS: Ascites was present in 47% (8/17) of patients with peritoneal seeding The right subhepatic space (n=6, 35%) and right paracolic gutter (n=5, 29%) but not the cul-de-sac (n=2, 12%)-were common sites of fluid collection. Permeative changes in the omentum and mesentery were seen in 18% (3/17) and 12% (2/17) of patients, respectively. Among five controls with false positive results, ascites in the cul-de-sac was present in three (two males and one female, 12%) while omental nodules and a thickened peritoneum were found in two (8%) and one (4%), respectively. In nine controls with false negative results, small disseminated nodules were seen in the mesentery and omentum at surgical field. The sensitivity and specificity of spiral CT were 47% (8/17) and 79% (19/24), respectively. CONCLUSION: In terms of sensitivity and specificity, spiral CT is not especially accurate in distinguishing peritoneal seeding from gastric carcinoma.

Primary Serous Papillary Carcinoma of the Peritoneum: A Case Report

Primary serous papillary carcinoma of the peritoneum is a rare neoplasm arising from the mesothelium. Histologically it is indistinguisable from ovarian serous papillary carcinoma, but it should be free of tumor or involved only superficially with the ovary. Radiologically its common findings are peritoneal and omental masses with ascites, and it is indistinguisable from peritoneal carcinomatosis or malignant mesothelioma. We report a case of surgically proven primary serous papillary carcinoma of the peritoneum in a 63-year-old woman.

Ultrasound-guided Biopsy of the Thickened Peritoneal Reflections: Efficacy and Diagnostic Role in the Differential Diagnosis of Peritoneal Tuberculosis and Peritoneal Carcinomatosis

PURPOSE: To evaluate the accuracy and safety of ultrasound-guided biopsy of the thickened peritoneal reflections and to determine the efficacy and diagnostic role of this procedure in the differential diagnosis of peritoneal tuberculosis and peritoneal carcinomatosis. MATERIALS AND METHODS: Twenty-seven patients with only mildly thickened (25 mm or less) peritoneal reflections without apparent mass formations, and in whom imaging findings were not diagnostic, underwent ultra-sound-guided biopsy. Five-MHz linear or convex linear array transducers were used for ultrasound guidance,and an automated gun with 18-gauge (n = 23) or 20-gauge (n = 4) needles for tissue sampling. Biopsies were performed on the thickened parietal peritoneum (n = 9), greater omentum (n = 11), and small bowel mesentery (n = 7), and the results were compared with the final diagnosis determined by adiologic/clinical follow-up (n = 17) or laparoscopic biopsy (n = 10). Complications and changes in hemoglobin and hematocrit levels after the procedure were evaluated. RESULTS: Specimens adequate for pathologic examination were obtained in all 27 patients. The histopathologic results were metastatic carcinomatosis (n = 15), peritoneal tuberculosis (n = 8), and chronic granulomatous inflammation (n = 4). Specific pathologic diagnosis was obtained in all patients except the four with chronic granulomatous inflammation. Differentiation between benignancy and malignancy was possible in all patients and the histopathologic specific accuracy rate was 100%. No clinically significant complications were observed. In 24 patients with ascites at the site of the biopsy, transient bleeding was observed immediately after the procedure, but this stopped spontaneously within a few minutes. Post-procedural hemoglobin and hematocrit levels were only minimally lower (mean values of 0.9g/dL and 3.0%, respectively) than pre-procedurally. CONCLUSION: Ultrasound-guided biopsy of thickened peritoneal reflections is a safe and effective diagnostic procedure and is useful in the differential diagnosis of peritoneal tuberculosis and peritoneal carcinomatosis.

Desmoplastic Small Round Cell Tumor: Radiologic Findings

PURPOSE: To evaluate the radiologic findings of intra-abdominal DSRCT. MATERIALS AND METHODS: We reviewed sixcases of pathologically proven DSRCT of the abdomen. Five of these patients were men and one was a woman ; theiraverage age was 26.8 years. We retrospectively analyzed CT(n=6) and MRI(n=4). RESULTS: In all patients, largerelatively well defined lobulated mass was seen;this arose from the peritoneal surface, and its average size was12.6(range, 10-18)cm. After the administration of contrast material, the masses showed inhomogeneous enhancement,and in addition, the following features were seen: irregular internal septations (n=5); necrosis (n=3); andamorphous calcification (n=4). Various associated findings such as ascites (n=4) and multiple para-aortic lymphnode enlargement (n=4) were present; omental cake (n=5), liver metastasis (n=1), cervical lymphadenopathy (n=1),hydronephrosis (n=1), small bowel obstruction (n=1), scrotal swelling (n=1) and collateral vessels by encasedaorta and renal vein (n=1) were also seen. CONCLUSION: In young male patients with a large heterogeneous enhaneedcalcified abdominopelvic mass and findings of carcinomatosis on both CT and MR images, DSRCT should be inelvded inthe differential diagnosis.

Intraabdominal Desmoplastic Small Round Cell Tumor: Report of Two Cases

Intraabdominal desmopl small round cell tumor is a rare neoplasm predominant in adolescent or young adult male. The tumor is characterized by widespread growht along the peritoneal surfaces of the abdomen and pelvis,typical histologic features, and a specific immunohistochemical staining pattern. We report the clinical,radiologic, and pathologc findings of intraabdominal desmoplastic small round cell tumor.

CT Findings of Peritoneal Tuberculosis and Peritoneal Carcinomatosis: Relationship between Peritoneal Change and Omental Infiltration

PURPOSE: To compare the CT findings of peritoneal tuberculosis (PT) and peritoneal carcinomatosis (PC) based on the morphologic features of the peritoneum and assess the relationship between the degree of peritoneal thickness and the severity of omental infiltration in PT and PC. MATERIALS AND METHODS: We retrospectively reviewed the CT findings of 15 patients with PT and 14 with PC. We checked the morphologic changes of the peritoneum as seen on CT, for the following points: 1) the presence of peritoneal change: 2) the pattern of any change-diffuse thickening, plaque or nodularity, combined thickening (diffuse and plaque, or nodularity); 3) the degree of thickness on the whole peritoneum - mild (grossly definite, but not more than 3 mm), moderate (more than 3mm); 4) the presence of irregularity on the peritoneal surface. We also evaluated the significance of the relationship between peritoneal thickness and omental infiltration in both disease entities. The degree of omental infiltration was described as follows : grade I (no change or focal smudge pattern); grade II ( diffuse smudge), grade III (omental cake regardless extent). RESULTS: Peritoneal change was seen in 12 of 15 PT patients and in 7 of 14 PC patients. In all 12 PT patients, the pattern of change was diffuse thickening, and among the seven PC patients, there was diffuse thickening in one, plaque or nodular thickening in four, and combined thickening in two. In PT patients, the degree of thickness on the whole peritoneum was mild in six and moderate in six, and in PC patients it was mild in two and moderate in one. An irregular peritoneum surface was seen in one patient with PT and in two with PC. The degree of omental infiltration in PT was grade I in four patients, grade II in six andgrade III in five. In PC, it was grade I in six patients, grade II in two and grade III in six. Smooth diffuse thickening of the peritoneum was seen in 11 of 15 PT cases and in one of 14 PC (P0.5). CONCLUSION: In PT and PC different CT findings based on peritoneal morphologic changes might be useful in differentiating these two entities. In addition, careful observation of relationship between the peritoneal change and the severity of omental infiltration is necessary.

Multicystic Mesothelioma of the peritoneum: A case Report

We report a case of multicystic mesothelioma in the visceral peritoneum anterior of the ascending colon. A 39-year-old female patient visited hospital with a palpabel tender mass in the right flank. An ultrasonogram showed multiple cystic mass lesions in the right flank and CT scan showed a multicystic rative mass with enhancing wall and septum in front of the ascending colon. The patient underwent explolaparotomy and the mass. which inpathology turned out to be a benign multicystic masothelioma, was removed.