Positron emission tomography image on evaluating intraperitoneal dissemination of malignant gastrointestinal stromal tumor

Herein is a report of a patient with gastrointestinal stromal tumor (GIST) possibly arising from greater omentum accompanying diffuse peritoneal disseminatation. Positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) revealed that 18F-FDG uptake was widely spreading in the abdomen. In this case, the PET image was more useful than computed tomography (CT) for understanding tumor distribution rather. PET provides important information on tumor distribution and has an impact on evaluating clinical stage in GIST patients.

[A case of omental mesothelioma presenting with laminar thickening of omentum-appearances of diffuse malignant peritoneal mesothelioma]

A man in his 60's with no apparent history of asbestos exposure was admitted to our hospital with a chief complaint of abdominal fullness. CA125 levels in serum and ascites were veryhigh. Enhanced abdominal CT confirmed a large amount of ascites, inflexible intestinal canal, short mesentery and laminar thickening of the omentum. SPIO-enhanced MRI-T1WI slightly enhanced the thickened omentum. These T1WI images largely matched portal-phase contrast CT images. Furthermore, the thickened omentum was clearly visualized by lowering the signal for the liver and spleen by SPIO and by suppressing the ascites signal by fluid-attenuated inversion recovery (FLAIR). Gascintigraphy confirmed Ga accumulation in the same areas. Chemotherapy was ineffective, and the patient died of liver metastasis in February 2006. Autopsy confirmed biphasic malignant peritoneal mesothelioma. The involvement of asbestos is clear in the onset of malignant peritoneal mesothelioma. Therefore, it is possible that the patient unintentionally inhaled asbestos. Hence, when levels of CA125 in serum and/or ascites are high, it is important to differentiate malignant peritoneal mesothelioma from primaryserous papillary carcinoma of the peritoneum. Here, we experienced a case of biphasic diffused omental mesothelioma. While studies have documented laminar thickening of the omentum by abdominal incision, this is thought to be first case in Japan in which laminar thickening of the omentum was detected on diagnostic imaging. Laminar thickening of the omentum and short mesentery are thought to be characteristic features of diffused peritoneal mesothelioma when subjective symptoms appear. In addition, Gascintigraphy and FDG-PET are useful auxiliary diagnostic tools. In the future, we hope to differentiate epithelial, sarcomatous and biphasic types based on imaging findings.

Ultrasound-guided biopsy of greater omentum: an effective method to trace the origin of unclear ascites

OBJECTIVES

Thickened greater omentum is encountered with high frequency in patients with ascites. The purpose of our study was to assess the utility of greater omentum biopsy under the guidance of ultrasound (US) in tracing the origin of unclear ascites and differentiating benign and malignant ascites.

MATERIALS AND METHODS

We retrospectively reviewed our institutional database for all records of greater omentum biopsy cases. One hundred and ninety-four patients with unclear ascites and thickened greater omentum were included in the study. The sonograms of greater omentum were evaluated before undergoing the ultrasound-guided biopsy and a biopsy was considered successful if a specific benign or malignant diagnosis was rendered by the pathologist.

RESULTS

Successful biopsy was rendered for 182 biopsy procedures (93.8%, 182/194) including tuberculosis (n=114), chronic inflammation (n=3), metastases (n=58), malignant mesothelioma (n=6) and pseudomyxoma peritonei (n=1). Twelve biopsies were non-diagnostic. According to the results of biopsy and follow-up, the sensitivity and specificity of biopsy in distinguishing malignant ascites from benign ascities were respectively 95.6% (65/68) and 92.9% (117/126). The greater omentum of 84 cases of tuberculous peritonitis showed "cerebral fissure" sign and was well seen as an omental cake infiltrated with irregular nodules when involved by carcinomatosis. No "cerebral fissure" sign was observed in peritoneal carcinomatosis. The sensitivity and specificity of this sign in indicating the existence of tuberculous peritonitis were 73.5% (89/121) and 100% (73/73). Moreover, if the specific "cerebral fissure" sign was combined with the biopsy results, the specificity of biopsy in distinguishing malignant ascites from benign ascits increased to 96.8% (122/126).

CONCLUSION

Ultrasound-guided biopsy of greater omentum is an important and effective method to diagnose the unclear ascites for patients with thickened omentum if certain techniques could be paid attention to. "Cerebral fissure" sign of greater omentum was a specific sign in indicating the tuberculous peritonitis and could increase the specificity of biopsy in distinguishing malignant ascites from benign ascits if combined with the biopsy results.

A study of multi-detector row CT scan on greater omentum in 50 individuals: correlating with anatomical basis and clinical application

BACKGROUND

In view of the descriptions of the CT manifestations on the greater omentum (GO) were not precise and detailed enough in the previous literature, we tried to evaluate the radiologic-anatomical features of the GO and to address the related clinical implications for the radiologic diagnosis and surgical application.

METHODS

We evaluated the GO by using multi-detector row CT (MDCT) scanning in 50 individuals correlating with anatomical basis and clinical application. Emphasis was placed on the following items: the anatomical distribution and location of the GO; the CT manifestations of the vasculature, fatty tissue and lymph nodes.

RESULTS

The gastro-epiploic vessel, the landmark for delineating the GO, was visualized in 50/50 cases (100%). The gastro-colic vein was detected in 34/50 cases (68%). The free-hanging portion, 48 cases revealed, seemed to have the capability of 'migration': it is located in the subphrenic spaces in 9/48 cases (19%) and distributed in the right lower quadrant predominantly in 10/48 cases (21%). Three-dimensional reformatted images, obtained in five cases, demonstrated the return of the gastro-epiploic vein distinctly. Lymph nodes were rarely detected within the GO.

CONCLUSION

The depicted omental vessels, visualized by using multi-planar reconstruction images together with three-dimensional reformatted images, played a crucial role in delineating the GO comprehensively. It can provide the valuable data for the radiologic diagnosis and surgical therapy planning including surgery of reconstruction, pancreas, portal hypertension as well as infections and neoplastic diseases.

Intraabdominal counter clockwise gastric volvulus incarcerated through a defect of the lesser omentum: CT diagnosis

We report the probably first case of incarcerated intra-abdominal gastric volvulus protruding through a defect of the pars flaccida of the lesser omentum. The 79-year-old woman presented with acute symptoms of upper gastrointestinal occlusion. Plain film radiographs, endoscopy and attempts at opacifying the upper alimentary tract failed to make the correct diagnosis. The definite preoperative diagnosis was achieved by mdCT thanks to high quality multiplanar reconstruction (MPR). In the reported case coronal oblique MPR views and vascular volume rendering views (VR) were of particular interest for the preoperative diagnosis.

Omental torsion without a whirl sign

Omental torsion is a very rare cause of acute abdomen. Its primary diagnostic modality is CT. The whirl sign visible in CT images is pathognomonic. The whirl sign is not present in all cases. When no whirl sign is seen, omental torsion is rather difficult to be differantieted radiologically from omental infarct and epiploic appendicitis. The diagnosis of these three entites is clinically important due to their different treatments. We present in this paper an omental torsion case where whirl sign was not present and diagnosis was made by other suggestive CT image findings.

Idiopathic segmental infarction of the greater omentum diagnosed by unenhanced multidetector-row CT and treated successfully by laparoscopy

Idiopathic segmental infarction of the greater omentum is a rare disorder presenting with nonspecific clinical symptoms that may mimic a variety of acute abdominal conditions. We describe the diagnosis and treatment of two patients who had idiopathic infarction of the greater omentum and presented with localized abdominal pain, mimicking acute cholecystitis and acute diverticulitis, respectively. Patients underwent unenhanced multidetector-row computed tomography (CT) examination, which demonstrated the characteristic features of omental infarction, consisting of a heterogeneous density fatty mass, containing hyperattenuating streaks, located in the greater omentum, between the anterior abdominal wall and the colon; a moderate amount of free peritoneal fluid was also present. There were no other pathological abdominal findings. Giving persisting and worsening symptoms, both patients underwent laparoscopy with resection of the necrotic portion of the omentum. Pathology confirmed the preoperative diagnosis. Unenhanced CT allows us to obtain a reliable diagnosis of omental infarction in patients with acute abdominal pain and may help in selecting the appropriate medical or surgical therapy.

Segmental omental infarction

Acute right-sided abdominal pain is a common presenting symptom in the emergency department. Acute cholecystitis and acute appendicitis are the most likely etiologies for right upper and lower quadrant pain, respectively. However, other differential possibilities include right-sided diverticulitis and perforated colon carcinoma. This case report of an 18-year-old man with segmental omental infarction highlights a much less frequent, self-limited cause of right-sided abdominal pain, which is increasingly identified on computed tomography scans.

Greater and lesser omenta: normal anatomy and pathologic processes

The peritoneum is the largest serous membrane in the body and the one with the most complex structure. The omentum is a double-layered extension of the peritoneum that connects the stomach to adjacent organs. The peritoneal reflections form the greater and lesser omenta, and the natural flow of peritoneal fluid determines the route of spread of intraperitoneal fluid and consequently of disease processes within the abdominal cavity. The omenta serve both as boundaries for disease processes and as conduits for disease spread. The omenta are frequently involved by infectious, inflammatory, neoplastic, vascular, and traumatic processes. Computed tomography (CT) is a primary diagnostic method for evaluation of omental diseases, most of which may manifest with nonspecific clinical features. Multidetector CT with multiplanar reformation allows accurate examination of the complex anatomy of the peritoneal cavity, knowledge of which is the key to understanding the pathologic processes affecting the greater and lesser omenta.

Small bowel infarcts in Degos disease

Degos disease is a rare idiopathic vasculopathy with multisystem involvement. We present a previously healthy 40-year-old woman who developed spontaneous small bowel infarctions and perforations 17 months after presentation with characteristic skin lesions. The abdominal CT findings of Degos disease, which have not been previously depicted in the radiology literature, are discussed.

Sonographic features of female pelvic tuberculous peritonitis

OBJECTIVE

The purpose of this study was to evaluate the sonographic features of tuberculous peritonitis in an attempt to facilitate the recognition of this disorder preoperatively.

METHODS

The sonographic findings of 16 patients who had tuberculous peritonitis were reviewed.

RESULTS

The sonographic findings showed that 14 of the 16 patients had ascites; 10 of these had fine, complete and incomplete mobile septations. Of these 10 patients, 4 had ascites with a latticelike appearance, and 2 had ascites with a parallel violin string appearance, which to our knowledge has not been described previously; 3 had particulate ascites. Peritoneal and omental thickening or nodules were identified in 9 patients. Two patients showed bilateral complex adnexal masses with multiloculated fluid with a thick wall-like tubo-ovarian abscess.

CONCLUSIONS

Tuberculous peritonitis seems to have characteristic sonographic features, especially the findings of peritoneal and omental thickening and ascites with fine, mobile septations. These sonographic findings may provide valuable information to help with further investigations and may prevent unnecessary laparotomies.

Nonoperative management of omental infarction: a case report in a child

Omental infarction is a rare entity in children that is usually diagnosed during surgery for suspected appendicitis. We report the clinical case of an obese boy presenting with abdominal pain and right-sided tenderness without fever, anorexia, or leukocytosis. Abdominal ultrasonography suggested omental infarction, and computed tomography confirmed the diagnosis. Nonoperative management was adopted with rapid and uneventful recovery. Nonoperative treatment of omental infarction is safe and effective; accurate diagnosis is therefore crucial to enable a conservative approach. Suggestive clinical features and diagnostic workup are addressed.

[Malignant tumor with false negative 18F-FDG PET image]

OBJECTIVE

To investigate the FDG uptake characteristics, the factors affecting 18F-FDG uptake and the extra CT diagnostic value of 18F-FDG PET/CT scan in the malignant tumor with false negative 18F-FDG PET image.

METHODS

The data of PET/CT image in 17 patients with various kinds of cancers were reviewed and analyzed by visual observation and semi-quantity analysis ( SUV). The results were compared with the CT and histopathological diagnosis, respectively.

RESULTS

Of 6 well-differentiated HCC patients confirmed by histopathological diagnosis, one had two lesions in the right lobe of the liver. One of these two lesions showed low FDG uptake on 18F-FDG PET scan and low density on CT scan. The other one was not shown on either 18F-FDG PET or plain CT scan. But on enhanced CT scan, these two lesions were found to be inhomogeneous with high density at arterial phase. The false negative 18F-FDG PET images of one gastric signet ring cell carcinoma in the gastric fundus with right adnexa metastasis, 3 renal cell carcinoma, one greater omentum and peritoneal metastatic adenocarcinoma and one well-differentiated prostate cancer were caused by normal physical uptake in the digestive tract or FDG retention in the urinary system due to normal excretion. The size of three metastases was smaller than or equal to 1 cm in diameter, however, two primary lesions of these metastases showed high FDG uptake and only one was negative on either 18F-FDG PET or CT scan. In this series, 68.8% of the primary tumors and 66.7% of metastases were found to show abnormal density on CT scan, and 31. 2% of the primary tumors and 33. 3% of metastases were not detectable on either PET or CT images.

CONCLUSION

False negative 18F-FDG PET in malignant tumor may be correlated with the pathologic type, differentiation degree and the lesion size. Combining CT information with PET or paying attention to the scan methods during 8 F-FDG PET examination may reduce the rate of false negative 18F-FDG PET diagnosis in various kinds of malignant tumors.

Radiological-pathological correlation in lipoblastoma and lipoblastomatosis

BACKGROUND

Lipoblastoma and lipoblastomatosis are uncommon benign mesenchymal lesions that predominantly occur in infancy and early childhood.

OBJECTIVE

To evaluate the imaging and histological features of lipoblastoma and lipoblastomatosis.

MATERIALS AND METHODS

Retrospective review of the radiological and pathological findings in children with lipoblastoma and lipoblastomatosis treated at a single centre between 1997 and 2004.

RESULTS

Eight children (median age 18 months) had undergone imaging and surgery at our institution. An infiltrative growth pattern was identified at imaging in two children with lipoblastomatosis, and a well-defined mass in six children with lipoblastoma. In all patients, imaging showed a lesion composed mostly, but not entirely, of fat. There were no recurrences at follow-up of between 1 and 91 months.

CONCLUSION

In infancy and early childhood, the identification of a tumour composed mostly of fat should suggest the diagnosis of lipoblastoma or lipoblastomatosis.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

[Fistulography in destructive pancreatitis in postoperative period]

Results of different x-ray methods applied in 151 patients early after operations for destructive pancreatitis were analyzed. The technique of fistulography is described. Plain roentgenography of the chest demonstrated changes in 77.4% cases, most often occurred disk-shaped atelectases and pleural effusion. Examination of the abdominal cavity revealed functional disorders in 69.8% cases, direct symptoms of purulent process -- in 52.9%, radiographic signs of aseptic sequestration -- in 47.1% patients. X-ray signs of purulent process in the retroperitoneal fat and aseptic sequestration of the infiltrate or fat are outlined. The value of fistulography for localization and determination of the shape of drained cavities, position of the drainage tubes in the cavity, condition of the adjacent tissue, progression of purulent process, adequacy of drain of the purulent cavities is shown. Based on the results of complex x-ray examination with ultrasound investigation and CT data, the indications to repeated procedure (surgery or additional drainage) were formulated in 82 (54.3%) of 151 patients.

Omental lipoblastoma in a child: diagnosis based on CT density measurements

A 2-year-old girl presented with an abdominal mass which on CT was central and hypodense. Housefield units measured -60 which made the diagnosis of a fatty mass. The diagnosis of an omental lipoblastoma was confirmed after surgery on histology.

Ultrasound and color power Doppler in the detection of metastatic omentum: a prospective study

OBJECTIVES

To analyze prospectively the ability of ultrasound to detect metastatic omentum in patients with suspicious pelvic masses and to describe the sonographic features of metastatic omental disease.

METHODS

One hundred and eighty-four patients were evaluated preoperatively by ultrasound examination and of these 173 were used in the analysis. We defined as an ultrasound-positive examination one which visualized intra-abdominal aperistaltic solid tissue, located above the bowel loops and below the anterior peritoneal surface. Preoperative sonographic findings were compared with pathological results.

RESULTS

Sonographic detection of metastatic omentum was achieved in 104 of 173 patients (60.1%), appearing as either solid aperistaltic tissue (80.8% of cases), or as solid discrete nodules (19.2%). When considering the echostructure of the surrounding bowel loops, this tissue appeared hypoechoic in 46 (44.2%) cases and isoechoic or slightly hyperechoic in the other 58 (55.8%) cases. In the overall series, the negative and positive predictive values (NPV and PPV) and the accuracy of ultrasound examination were 92.7%, 91.3% and 91.9%, respectively. When considering only the group of ovarian tumors, the NPV, PPV and accuracy were 91.9%, 94.6%, and 93.8%, respectively.

CONCLUSION

Ultrasound examination is highly accurate in detecting metastatic omental involvement in cases with suspicious pelvic masses.

Omental torsion with right-sided inguinal hernia

Omental torsion is a rare cause of acute abdomen. The diagnosis is usually not established before surgery, but recently some reports have described the usefulness of computed tomography (CT) for the detection of this condition. We encountered a 58-year-old man with torsion of the greater omentum secondary to right-sided inguinal hernia, and present the characteristic CT findings of a whirl-like mass with hyperattenuated fatty tissue.

Adult metastatic pancreaticoblastoma detected with Tc-99m MDP bone scan

Osteotropic radiopharmaceutical uptake has been reported in a wide variety of benign and malignant soft tissue tumors. We present an unusual case of pancreaticoblastoma with mesenteric and omental metastases detected by bone scan in a 69-year-old man who presented with fever, weight loss, and renal insufficiency. Pancreaticoblastoma is a rare childhood tumor that may occur in adults, although only two cases of adults with metastatic disease have been described.