Evaluation of (pre-)malignant colonic abnormalities: endoscopic validation of FDG-PET findings

The diagnostic accuracy of 2-[¹⁸F]-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) for the detection of (pre-)malignant lesions of the colon was compared with that of endoscopy. We selected a cohort of 39 patients [13 females and 26 males; mean age 62.3 years standard deviation (SD) 9.6 years] who underwent both FDG-PET and endoscopy (total of 44 procedures) in a 2-year period with a maximum interval between the examinations of 3 months (mean 30 days, SD 28 days). The underlying pathology was colorectal malignancies (24 patients), other malignancies (nine patients) and other disorders (six patients). Follow-up of resected colorectal cancer was the most common reason for the performance of endoscopy. In 19 patients FDG bowel uptake was interpreted as non-physiological, and in 18 patients abnormal findings (adenomatous polyps >3 mm or carcinoma) were detected by endoscopy. Compared with colonoscopy, FDG-PET had a sensitivity of 74% and specificity of 84%. The positive predictive value of FDG-PET was 78%. FDG-PET failed to detect small (diameter 3-10 mm) polyps in four patients. In nine cases abnormal FDG accumulation on PET imaging was the sole reason for performance of an endoscopic procedure. In these cases, endoscopy detected large adenomatous polyps in four patients and carcinomas in two patients, but no abnormalities were detected on endoscopy in the other three patients. There was a good correlation between the location of FDG uptake and endoscopy-positive lesions. FDG-PET is able to detect clinically relevant lesions of the colon. Our study suggests that it can be regarded as a useful adjunct in the non-invasive follow-up of patients with colorectal carcinomas.     

FDG uptake in colonic villous adenomas

Colonic adenomas constitute 70-80% of all colorectal polyps, and their clinical significance relates primarily to their relationship with colorectal cancer. The malignant potential of the polyps detected by FDG-PET is unknown, as not all the colonic lesions identified by FDG-PET represent colorectal malignancies. The purpose of this study was to investigate the rate of FDG-PET positivity within colonic villous adenomas. A pathology database search was performed to identify all patients diagnosed with colonic villous adenoma between June 1, 1996 and December 1, 2000. Patients with a pathologic diagnosis of colonic villous adenoma and who also had a FDG-PET study up to 1 month before colonoscopy were included in this study. FDG-PET findings were compared with pathological features. Of more than 4,000 patients, six patients were diagnosed with colonic adenoma on subsequent colonoscopy following FDG-PET study. Based on the pathological findings, these 6 patients had a total of 2 villous and 9 tubulovillous adenomas. Five of the 6 patients showed foci of increased FDG uptake in the region of the colon that corresponded to the villous adenoma(s) detected on colonoscopy, which accounted for a true-positive rate of 83.3% (5/6 subjects). Focal lesions in the colon seen on FDG-PET examinations need to be investigated further, even though some of these will prove to be villous adenomas rather than colorectal carcinomas. Future studies in a larger number of patients are needed to evaluate the relationship of histopathological features of colonic polyps and detectability of these lesions by FDG-PET.     

Incidental colonic focal lesions detected by FDG PET/CT

OBJECTIVE: The aim of this study was to assess the performance of FDG PET/CT for the detection of colonic lesions, especially advanced neoplasms (villous or >10-mm adenomas, carcinomas). Because of 18F FDG accumulation in adenomatous polyps, PET using FDG can detect early premalignant colorectal lesions. MATERIALS AND METHODS: FDG PET/CT studies performed for a 1-year period in 1,716 consecutive patients with various malignant diseases, except colorectal cancer, were retrospectively reviewed. PET images obtained 1 hr after FDG injection and non-contrast CT images used for attenuation correction were fused for analysis. Of 45 patients showing intense focal colonic FDG uptake, 20 patients (with 21 foci) underwent a colonoscopic investigation, and, when necessary, polyp resection. The intensity of FDG uptake was quantified using the standardized uptake value (SUV(max)). RESULTS: The FDG colonic foci were associated with 18 colonoscopic abnormalities in 15 patients, with no colonic abnormality detected in five patients (false-positive [FP] results). Histopathologic findings revealed advanced neoplasms in 13 patients (13 villous adenomas and three carcinomas) and two cases of hyperplastic polyps. A difference in the mean SUV(max) was found between FP and true-positive colonic FDG foci but was not statistically significant (p = 0.14). CONCLUSION: Presence of a focal colonic FDG uptake incidental finding on a PET/CT scan justifies a colonoscopy to detect (pre-)malignant lesions. The fusion of PET and CT images allows an accurate localization of the lesions. PET/CT is a useful tool to differentiate pathologic from physiologic FDG uptake.     

Ability of FDG-PET to detect all cancers in patients with familial adenomatous polyposis, and impact on clinical management

Purpose Familial adenomatous polyposis (FAP) is characterised by colonic and duodenal adenomatous polyps that carry a risk of malignant transformation. Malignant degeneration of duodenal adenomas is difficult to detect. We speculated that 2-(¹⁸F)-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) might be able to detect early duodenal cancer in FAP. Accordingly, we investigated the role of FDG-PET in the management of FAP patients.Methods FDG-PET was performed in 24 FAP patients. Eight had advanced duodenal adenomas (Spigelman IV), including two patients with duodenal cancer. Scans were defined as positive on the basis of focal FDG accumulation.Results Pathological FDG accumulation was absent in 19 of 24 patients. All six patients with Spigelman IV duodenal adenomas (without cancer) were negative; two of these underwent a duodenectomy and pathological examination did not reveal duodenal cancer. In five patients, FDG-PET revealed significant uptake, in the duodenum (2), lower abdomen (1), lung (1) and multiple sites in the abdomen (1). These hot spots correlated with duodenal cancer (2), abdominal metastasis (1) and sclerosing haemangioma of the lung (1). We failed to make a histopathological diagnosis in the single patient with multiple intra-abdominal sites of FDG uptake. None of the patients from the FDG-PET-negative group developed cancer during follow-up (mean 2.8 years).Conclusion FDG-PET detected all the cancers present, and none of the patients with negative FDG-PET developed cancer. This suggests that positive FDG-PET in FAP patients should lead to further examinations to rule out cancer. In patients with negative FDG-PET a more conservative approach seems justified.     

Noninvasive monitoring of colonic carcinogenesis: feasibility of [(18)F]FDG-PET in the azoxymethane model

BACKGROUND: Azoxymethane (AOM) is a potent carcinogen that induces colorectal cancer and adenomas in rats. [(18)F]FDG-PET is a molecular imaging technique that is based on the elevated uptake and retention of radiolabeled glucose. At present, it is unknown at which stage FDG accumulation occurs during the adenoma carcinoma sequence. To address this issue, we studied the FDG uptake in AOM-induced rat colorectal adenocarcinoma (CRC) and correlated this with histopathological findings. METHODS: Seventy Fischer 344 rats were injected with AOM. Terminal autopsy took place 20-38 weeks after the first AOM injection. After [(18)F]FDG PET scanning, the rats were sacrificed, tissue [(18)F]FDG uptake was measured, followed by histopathological examination. RESULTS: Macroscopic examination revealed 21 tumors (7 located in the small bowel and 14 in the colon) in 19 rats. On histological examination, we found 10 colonic adenocarcinomas (the first being observed at Week 22) and 7 adenocarcinoma in the small bowel. In total, seven colon adenomas were found in five rats, six of which expressed high-grade dysplasia. The [(18)F]FDG accumulation in small intestine carcinomas was well beyond background accumulation (P<.0001). On PET scanning, two rats showed focal accumulation of the abdominal area, corresponding to small intestine carcinomas. CONCLUSION: Adenocarcinomas had a significantly higher [(18)F]FDG uptake than background bowel uptake. [(18)F]FDG uptake was lower in adenomas than in carcinomas. These data suggest that the AOM model allows the evaluation of intervention strategies with [(18)F]FDG uptake as a valid outcome measure.     

Rapid detection of human infections with fluorine-18 fluorodeoxyglucose and positron emission tomography: preliminary results

The purpose of this study was to evaluate the feasibility of 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) and positron emission tomography (PET) for rapid detection of human infections. Eleven patients who were known or suspected to be harboring various infections were studied with FDG-PET. Dynamic scans over the putative infection sites were performed immediately after FDG (370 MBq) injection through 60 min, and static images including multiple projection images were then obtained. FDG uptake was assessed visually into four grades (0, normal; 1, probably normal; 2, probably abnormal; 3, definitely abnormal). For the semiquantitative index of FDG uptake in infections, the standardized uptake value of FDG normalized to the predicted lean body mass (SUV-lean, SUL) was determined from the images obtained at 50–60 min after FDG injection. PET results were compared with final clinical diagnoses. Eleven lesions in eight patients, which were interpreted as grade 2 or 3 by FDG-PET, were all concordant with active infectious foci. The SUL values of infections ranged from 0.97 to 6.69. In two patients, FDG-PET correctly showed no active infection. In one patient, it was difficult to detect infectious foci by FDG-PET due to substantial normal background uptake of FDG. In total, FDG-PET correctly diagnosed the presence or absence of active infection in 10 of 11 patients. Fusion images of PET with computed tomography showed the most intense FDG uptake to be within an abscess wall. In conclusion, FDG-PET appears to be a promising modality for rapid imaging of active human infections. More extensive clinical evaluation is warranted to determine the accuracy of this method. Received 5 March and in revised form 20 May 1998     

FDG-PET in infectious lesions: The detection and assessment of lesion activity

The usefulness of FDG-PET in the detection of infectious foci and the assessment of lesion activity was evaluated. The study covered 24 patients with 25 FDG-PET studies, including lesions of bacterial, tuberculous and fungal origins. The FDG uptake was determined by the lesion to muscle ratio (LMR) on the static images. The time activity curves (TACs) were classified into four patterns based on both the existence of an initial peak and a slope thereafter. A high FDG uptake was observed in 23 of 25 lesions (92%). Two lesions, in which no abnormal uptake was noted, included one in the healing stage and the other consisting of a cavity with a thin wall. The acute active lesions showed higher LMRs than the chronic active or healing lesions (mean ± SD: 9.8 ± 3.6, 3.6 ±1.8 and 4.3 ± 1.7, respectively, p < 0.05), and they could be approximately distinguished by an LMR of 6. The patterns of the TACs in acute or chronic active lesions were either an increase without an initial peak or a plateau, while those in the healing lesions demonstrated predominantly an increase with an initial sharp peak. Our results indicated that FDG-PET is clinically useful in the detection of the infection of miscellaneous microorganisms as well as in the assessment of lesion activity.     

Mucosa-associated lymphoid tissue lymphoma studied with FDG-PET: a comparison with CT and endoscopic findings

OBJECTIVE: We investigated the accumulation of 2-deoxy-2-[(18)F] fluoro-D: -glucose positron emission tomography (FDG-PET) in patients with mucosa-associated lymphoid tissue (MALT) lymphoma patients as compared with computerized tomography (CT) and endoscopic imaging. METHODS: FDG-PET was performed on 13 untreated patients with MALT lymphoma. CT scanning of the affected areas was performed in all the patients to compare with the FDG-PET images. In five patients with gastric MALT lymphoma, comparison was also made with the endoscopic findings. RESULTS: Of the 13 untreated MALT lymphoma patients, all 8 non-gastric MALT lymphoma patients exhibited abnormal accumulation of FDG. However, in the five gastric MALT lymphoma patients, no abnormal FDG accumulation was observed. Although lesions could be confirmed on CT images from the patients other than those with gastric MALT lymphoma, the mucosal lesions of gastric MALT lymphoma could be observed only by endoscopy. CONCLUSIONS: FDG-PET can be used to detect MALT lymphoma when it forms mass lesions, whereas it is difficult to detect non-massive MALT lymphoma of gastrointestinal origin.     

大肠息肉679例临床特征及内镜、病理学特点分析

 目的 研究大肠息肉患者的年龄,息肉的发生部位、大小、病理类型以及息肉癌变的相关规律.方法 对电子肠镜检查中检出的大肠息肉患者的临床表现、内镜特点及病理资料进行总结和分析.结果 在3 680例肠镜检查者中,发现大肠息肉679例,其中男468例,女211例,检出率18.45%; 好发年龄以30～69岁为主,占80.41%;炎性、增生性、腺瘤性、错构瘤性、幼年性息肉分别占33.87%、32.11%、31.37%、1.77%、0.59%;息肉部位分别为直肠34.18%、乙状结肠23.12% 、降结肠14.96%、横结肠12.13%、升结肠11.49%、盲肠4.11%.679例大肠息肉患者中有30例发生癌变,癌变率为4.42%.管状腺瘤、混合性腺瘤、绒毛状腺瘤癌变率分别为5.88%、4.21 %、23.08%.息肉直径≤1.0 cm,无癌变发生;1.1～1.9 cm息肉,癌变率4.24%;≥2.0 c m息肉,癌变率21.37%.结论 30～69岁大肠息肉发病率较高,年龄大于50 岁为危险因素,男性较女性更容易患大肠息肉;息肉好发部位为左半结肠;病理类型以炎性息肉、增生性息肉和腺瘤性息肉常见;左半结肠、直径≥2.0 cm息肉、绒毛状腺瘤容易癌变 ;发现大肠息肉应尽可能切除,并应建立良好的随访机制,内镜下切除大肠息肉可预防息肉癌变.     

The role of positron emission tomography with fluorine-18-deoxyglucose in identifying colorectal cancer metastases to liver

Liver metastasis is a common consequence of colorectal carcinoma. Early and accurate detection of liver metastasis is crucial for a decision about partial hepatectomy, which is considered a standard and potentially curative therapy in such a setting. The presence of extrahepatic metastases will exclude surgical resection as a therapeutic option. Positron emission tomography with fluorine-18-deoxyglucose (FDG-PET) has been successful in detecting and staging a variety of malignancies. The purpose of this study was to assess the utility of FDG-PET in the accurate detection of liver and distal metastases from colorectal cancer. The results of 80 PET and computed tomography (CT) scans were compared with surgical pathology and clinical outcome. FDG-PET detected liver metastases in 28 patients, with a sensitivity of 100%. CT detected metastasis in 20 patients, giving a sensitivity of 71.4%. In addition, in one patient with negative CT findings, PET detected a focus of hypermetabolism in the region adjacent to liver, which was proven to be a second focus of primary colon carcinoma. In six patients with liver metastases, PET correctly detected extrahepatic lesions, while CT only detected hepatic lesions. In conclusion, FDG-PET is an excellent imaging modality for the detection and staging of liver metastases in patients with colorectal carcinomas.     

Influence of rhTSH on [18F]fluorodeoxyglucose uptake by differentiated thyroid carcinoma

The influence of serum TSH levels on fluorine-18 fluorodeoxyglucose (FDG) uptake by recurrences or metastases of differentiated thyroid carcinomas has not yet been clarified. The aim of this study was to ascertain whether the administration of recombinant human thyrotropin (rhTSH) stimulates FDG uptake by such lesions. In this prospective study, 30 patients with positive or equivocal thyroglobulin (Tg) levels and negative or equivocal iodine-131 and/or morphological imaging results (ultrasound, MRI, CT) underwent FDG positron emission tomography (PET) under exogenous TSH suppression and under exogenous TSH stimulation of serum levels by injection of rhTSH. The mean interval between the FDG-PET studies under these two conditions was 9.3+/-8.8 weeks. Serum TSH levels and free thyroid hormones were determined on each occasion. FDG uptake was quantitated using tumour to background ratios (TBRs) and standardised uptake values (SUVs). Under TSH suppression there was focal FDG accumulation in nine subjects (22 tumour-like lesions). The total number of foci was 45. After exogenous TSH stimulation, the number of patients in whom FDG foci were detected was 19, and the number of foci identified was 82 (78 tumour-like lesions). TBR of regions showing positive FDG contrast with either of the modalities averaged 2.54+/-1.89, and under stimulated TSH levels, 5.51+/-2.99 ( P<0.0001). Corresponding SUVs were 2.05+/-1.45 versus 2.77+/-1.58 ( P<0.001). In a small number ( n=4) of foci related to inflammatory lymph nodes, TBR and SUV were only marginally increased under TSH stimulation (2.01+/-0.38 and 1.07+/-0.38, respectively), and the values did not differ significantly from those obtained under suppression. These results provide the first direct evidence that TSH stimulates FDG uptake by differentiated thyroid carcinoma and that, therefore, FDG-PET is more accurate under rhTSH than under suppression.     

Evaluation of 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography in gastric carcinoma: relation to histological subtypes, depth of tumor invasion, and glucose transporter-1 expression

OBJECTIVE: Variable uptake of 2-deoxy-2-[18F]fluoro-D-glucose (FDG) has been noticed in positron emission tomography (PET) studies of gastric carcinoma patients, with low uptake occurring especially in some particular histological subtypes and early carcinomas. But this phenomenon has not been adequately explained. The aim of the present study is to clarify FDG uptake in gastric carcinomas especially focusing on histological subtypes, the depth of tumor invasion, and glucose transporter-1 (GLUT-1) expression which is considered to be one of the major factors for higher FDG uptake in human malignant tumors. METHODS: FDG-PET was performed on 35 preoperative patients with gastric carcinoma. Forty macroscopically distinguishable lesions on a surgical specimen were histologically classified into two subtypes: Cohesive type (papillary adenocarcinoma, tubular adenocarcinoma, and solid type poorly differentiated adenocarcinoma) or Noncohesive type (signet-ring cell carcinoma and non-solid type poorly differentiated carcinoma). GLUT-1 expression was immunohistochemically determined. Histological parameters (GLUT-1 expression, histological subtypes, the depth of invasion, lymphatic permeation, venous invasion and tumor size) were evaluated, and factors for FDG uptake (detectability and the degree) and GLUT-1 overexpression were determined by multiple regression analysis. RESULTS: Nineteen of 40 gastric carcinomas showed detectable FDG uptake (48%), multiple regression analysis revealed that both the depth of invasion and histological subtypes are independent factors that influence the detectable FDG uptake in gastric carcinoma (R2 = 0.66). GLUT-1 expression was seen from an early cancer stage and the cohesive type was an independent factor influencing the overexpression of GLUT-1 (R2 = 0.66). GLUT-1 expression was the most influential factor for the degree of FDG uptake in gastric carcinoma (R2 = 0.68). CONCLUSIONS: This study provided important information on the clinical application of FDG-PET in gastric carcinoma that early or non-cohesive gastric carcinoma may show lower FDG uptake. Therefore, the usefulness of FDG-PET for the detection of gastric carcinoma is limited. But there is a possibility that FDG uptake associated with GLUT-1 expression may serve as a prognostic factor of gastric carcinoma representing tumor metabolism.     

Incidental detection of colon cancer by FDG positron emission tomography in patients examined for pulmonary nodules

PURPOSE: Fluorodeoxyglucose (FDG) positron emission tomographic (PET) imaging has been used extensively to diagnose cancer with high rates of sensitivity and specificity. One of its applications is to distinguish benign from malignant pulmonary nodules. It is common to observe colonic uptake on whole-body FDG-PET images. Because patients with lung cancer also tend to be in the age group with the highest incidence of colon cancer, the authors tried to assess the efficacy of FDG-PET for detecting occult colon cancer in patients referred for the evaluation of lung nodules. METHODS: The records of 500 consecutive patients referred for the evaluation of pulmonary nodules were reviewed retrospectively. Among the patients, 197 had no previous clinical or radiographic evidence of abnormalities in the gastrointestinal tract, and none had been found to have any cancer before undergoing an FDG-PET study. All colon lesions were verified either by histologic analysis or by clinical course. RESULTS: Among the 197 patients analyzed, 59 had diffuse colonic uptake in various segments of the colon. Seventeen of the patients had focal colonic uptake, five of which were proved to be colon cancer. CONCLUSIONS: The routine use of FDG PET to characterize lung lesions significantly increases the probability of detecting unexpected extrathoracic disease. In these patients, the incidental finding of colon cancer had an important effect on their treatment and may prove to be very cost-effective.     

The detection of local recurrent head and neck cancer with fluroine-18 fluorodeoxyglucose dual-head positron emission tomography

Primary tumors of the larynx and hypopharynx are preferably treated with high-dose radiation therapy. In these patients, it may be difficult to distinguish recurrent disease from post-treatment reactions. The aim of the present study was to assess the value of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) in the detection of local relapses of laryngeal or hypopharyngeal carcinoma after radiotherapy using a dual-head PET camera. Forty-eight patients (43 male, 5 female; mean age ±SD, 61±9.5 years) with suspected recurrent laryngeal or hypopharyngeal cancer were prospectively studied. The mean interval between initial treatment and suspicion of recurrent disease was 14.6 months (range: 3–100 months). FDG dual-head PET was followed by endoscopy with or without biopsy under general anaesthesia within a period of 2 months in all patients. The mean period of follow-up after FDG dual-head PET was 13.7 months. In 19 out of 31 patients with focally increased uptake, tumour recurrence (mean diameter: 2.4 cm; range 0.4–6.5 cm) was found at initial endoscopy. In five patients recurrence was found during follow-up with a mean interval of 6.6 months. Seven patients had a false-positive study due to benign lesions or swallowing artefacts. In none of the patients with a normal PET study was tumour recurrence found during follow-up. The sensitivity and specificity of FDG dual-head PET were 100% and 71%, respectively. It is concluded that FDG dual-head PET is highly sensitive for the detection of local recurrence of laryngeal and hypopharyngeal carcinoma after radiotherapy. Some lesions were detected with a mean interval of 6.6 months before histological confirmation. In patients suspected of having recurrent laryngeal or hypopharyngeal cancer in whom FDG-PET is negative, endoscopy may be omitted for at least 6 months and possibly for up to 1 year. Received 27 January and in revised form 15 March 1999     

CT attenuation of colorectal polypoid lesions: evaluation of contrast enhancement in CT colonography

The aim of this study was to calculate pre- and postcontrast CT attenuation values of benign colorectal polyp and carcinoma lesions detected by virtual colonoscopy, and to investigate whether contrast enhancement of these lesions can be potentially used for differentiation from residual fluid in the colon. Fifteen benign polyps and 21 colorectal carcinoma lesions detected by virtual colonoscopy in 18 patients were included in our study. All of the polyps and carcinoma lesions were confirmed by colonoscopic biopsy. Measurement of CT attenuation values was performed in precontrast (supine) and postcontrast (prone) scans for each polyp and carcinoma. The CT attenuation values of residual fluid in the colon was also measured from the same location before and after intravenous contrast administration. On unenhanced CT scan mean attenuation values of benign polyps and colorectal carcinomas were 32.4 and 42.6 HU, respectively. Following contrast enhancement, mean attenuation value increased to 78.9 HU for polyps and 90.7 HU for carcinomas. Increase in the CT attenuation values of these lesions was significant ( p <0.0001). Mean CT attenuation value of residual fluid before and after administration of IV contrast were 14.6 and 13.8 HU, respectively. The difference between CT attenuation value of residual fluid in the colon before and after contrast material was not significant ( p =0.29). Colorectal benign polyps and carcinomas demonstrate significant enhancement following contrast administration and use of intravenous contrast material during virtual colonoscopy may help in some cases in differentiating these solid lesions from residual colonic fluid that does not enhance. This paper was presented at RSNA 2001 meeting.     

550例大肠息肉的临床病理分析、内镜下治疗及随访

本文报道５５０ 例大肠息肉的临床及病理特点、内镜下治疗及１～２０ 年随访结果。大肠息肉的检出率为１４．０％ ，５０ 岁以上患者占 ４９．１％ ，单发性息肉 ４２０ 例，多发性息肉 １３０ 例，好发部位为乙状结肠和直肠（５０．５％ ）。病理诊断以腺瘤性息肉（４２．２％ ）和炎性息肉（４０．０４％ ）最多，息肉的异型增生发生率为１４．２％ ，腺瘤性息肉的癌变率为 １２．１％ ，结肠癌伴息肉的发生率为 ２．９％ 。对５４４ 例患者进行了内镜下息肉治疗，息肉的复发及再发率为５５．４％ ，平均复发时间为 ３２ 个月。随访检出４ 例息肉癌变，分别在术后第 ３、５、１０、２０ 年。     

An abnormal accumulation of fluorine-18-FDG PET in cytomegalovirus enteritis—A case report

The source of a fever of unknown origin (FUO) and watery diarrhea in a 63-yr-old female with a history of disturbance of consciousness due to moyamoya disease was examined. Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET), colonoscopy, blood analysis, and determination of cytomegalovirus (CMV) antigenemia were performed. FDG was found to be accumulated in the wall of a dilated colon, and extended from the transverse to sigmoid colon. Colonoscopy revealed edematous, inflammatory, and punched out lesions in accordance with the areas of abnormal FDG uptake. A biopsy specimen showed the antibody of CMV in the colonic mucosa, and CMV antigenemia was detected by an immunohistochemical assay using a monoclonal antibody for CMV pp65 antigen. From these findings, we strongly suspected CMV enteritis.     

Current status of nuclear medicine. Clinical application of FDG-PET for cancer diagnosis. Esophageal cancer

Positron emission tomography (PET) with [18F]-fluorodeoxyglucose (FDG) is a tool for the imaging and evaluation of glucose metabolism. This technique has recently become available in more than thirty hospitals and has been approved under Japan's national health insurance program. FDG uptake correlates with glucose utilization in tissue and is widely used for evaluating malignant tumors as well as brain function and myocardial viability. FDG-PET is useful for the diagnosis of lung cancer, colon cancer, esophageal cancer, malignant lymphoma, malignant melanoma, head and neck cancer, myocardial viability, and epileptic focus. A brief summary of the application and utility of FDG-PET for esophageal carcinoma is described in this article. Because of its limited spatial resolution, FDG-PET is not able to evaluate the invasiveness of primary tumors and small lesions. However, the uptake of FDG correlates with the aggressiveness of the tumor and the prognosis of patients with esophageal carcinoma. The sensitivity, specificity, and accuracy of lymph node staging is higher than that with CT. FDG-PET has the advantage of being able to detect distant metastases on a single occasion. Evaluation of the response to therapy and of recurrence is also possible by means of FDG-PET. There is some normal uptake and physiological distribution of FDG in many organs. Physiological status has an effect on the uptake of FDG in normal organs, and, consequently, on lesion uptake. Understanding of these characteristics makes this procedure a useful diagnostic modality for the management of patients with esophageal carcinoma.     

Sacral insufficiency fracture detected by FDG-PET/CT: Report of 2 cases

We report 2 cases of sacral insufficient fracture detected by FDG-PET/CT. In case 1, a 79-year-old female patient with malignant lymphoma, who had recent lumbago, received FDG-PET/CT examination. Vertical linear FDG uptake medial to bilateral sacro-iliac joint was observed on FDG-PET and a fracture line corresponding to FDG uptake was observed in bone window of CT images. In case 2, an 81-year-old male patient with colon cancer, who also complained of lumbago, received FDG-PET/CT examination. Vertical linear FDG uptake medial to bilateral sacro-iliac joint and horizontal uptake which connects vertical line (H-shaped) was demonstrated and CT also demonstrated a fracture line corresponding to FDG uptake. H-shaped high intensity area corresponding to FDG uptake was observed on T2-weighted image of MRI. On bone scintigraphy, H-shaped uptake was also observed. Like bone scintigraphy, typical H-shaped FDG uptake may be diagnostic in sacral insufficiency fracture. Adding CT information to FDG-PET, that is, assessing SIF with FDG-PET/CT may be useful when atypical findings are observed.     

26. Incidental findings should be included in the analysis of cost-effectiveness for evaluation of pulmonary nodules by FDG-PET

Background: In cost-effective analysis regarding to utilization of FDG-PET on lung nodules, most studies focused on lung lesions themselves (benign vs. malignant) and possible metastases if primary lesion is malignant. However, in a patient with pulmonary nodules, abnormal sites of increased FDG uptake on a whole-body PET scan may either the primary tumor or lesions unrelated to lung malignancy. The incidence of detection of the unsuspected lesions, which often changes the management of these patients, should also be included in the cost-effective analysis.Methods: We retrospectively analyzed 213 cases referred for evaluation of pulmonary nodules. 89 of them proved to have lung malignancy and were excluded in our study. None of the remaining 124 patients had prior clinical or radiographic evidence of other abnormalities before undergoing FDG-PET. All unsuspected lesions were verified either histologically or by the clinical course of the disease.Results: Among the 124 patients without lung cancer, FDG-PET revealed unsuspected abnormality in eight patients. These include other malignancy (colon cancer x 3, lymphoma x 1) and benign lesions (sarcoidosis x 3, cystic kidney x 1). None of the 124 patients studied had additional pathology found during follow-up.Conclusion: The routine uses of FDG-PET for characterizing the lung lesions significantly increases the chances detecting unexpected other pathology. The incidental FDG-PET findings of unsuspected lesions, especially those unrelated to lung cancers, no doubt have a major impact on the management of these patients and may prove to be cost-effective.