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

The diagnostic accuracy of 2-[(18)F]-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.     

PET imaging of musculoskeletal tumours with fluorine-18 α-methyltyrosine: comparison with fluorine-18 fluorodeoxyglucose PET

Fluorine-18 labelled !-methyltyrosine (FMT) was developed for positron emission tomography (PET) imaging, and its potential for clinical application in patients with brain tumours has been demonstrated. This is the first trial to compare FMT with ¹⁸F-fluoro-2-deoxy-d-glucose (FDG) for the evaluation of musculoskeletal tumours. Seventy-five patients were examined with both FMT- and FDG-PET within a 2-week period. Imaging findings were visually inspected in conjunction with computed tomography and/or magnetic resonance imaging, and standardized uptake values (SUVs) for both FMT and FDG in lesions were also generated and compared with histological findings. A significant correlation between FMT and FDG SUVs was found for all lesions (r=0.769, P<0.0001), and mean values for malignant tumours were significantly higher than those for benign lesions in both FMT- and FDG-PET. The diagnostic sensitivities and specificities for malignancy were 72.7% and 84.9%, respectively, using FMT with a cut-off SUV of 1.2, and 72.7% and 66.0%, respectively, using FDG with a cut-off SUV of 1.9. The resultant accuracy with FMT was 81.3%, higher than that for FDG (68.0%), and the difference with respect to specificity was significant (L²cal=5.0625, P<0.05). On the other hand, while a significant correlation was found between malignant tumour grade and SUV with both FMT- (A=0.656) and FDG-PET (A=0.815), only the latter demonstrated significant differences among grades I, II and III. FMT and FDG for PET appear equally effective at detecting musculoskeletal tumours. In evaluating musculoskeletal tumours, FMT may be superior to FDG in the differentiation between benign and malignant tumours, while FDG may be the better choice for non-invasive malignancy grading.     

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.     

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.     

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.     

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。     

18F-FDG PET detection of colonic adenomas.

The adenomatous polyp of the colon is clinically important as a precursor of colonic cancer. The aim of this preliminary study was to evaluate the potential usefulness of (18)F-FDG PET for detecting adenomatous polyps of the colon. METHODS: We performed a retrospective study of 110 subjects who underwent both PET study and total colonoscopy. On nonattenuation-corrected PET images, focal distinct FDG accumulation along the large intestine was considered a positive finding, and the PET results were compared with colonoscopic findings. Histology and adenoma size were determined by polypectomy. RESULTS: Fifty-nine adenomatous polyps, 5-30 mm in size, were found in 30 subjects by total colonoscopy. PET findings were positive for 14 of the 59 adenomas (24%). The positivity rate for PET images rose with the increase in size of the adenomas; it was 90% in adenomas (9/10) that were > or =13 mm. The overall false-positive rate was 5.5% (6/110 subjects). CONCLUSION: Increased glucose metabolism is observed in colonic adenomas, and detectability with PET increases with the increase in adenoma size. Adenomas are premalignant lesions, and it is important to realize that colonic adenomas may be found incidentally during an FDG PET study.     

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     

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.     

Correlation of Glut-1 glucose transporter expression with [18F]FDG uptake in non-small cell lung cancer

Positron emission tomography (PET) with [¹⁸F]2-fluoro-2-deoxy-D-glucose (FDG) may show negative results for bronchioloalveolar lung carcinoma. We investigated the correlation of Glut-1 glucose transporter expression with [¹⁸F]FDG uptake in non-small cell lung cancer. Thirty-two patients with 34 non-small cell lung cancers (7 bronchioloalveolar carcinomas, 23 non-bronchioloalveolar adenocarcinomas, 3 squamous cell carcinomas, and 1 adenosquamous cell carcinoma) were studied. Final diagnoses were established by histology (via thoracotomy) in all patients. [¹⁸F]FDG PET was performed 40 min after i.v. injection of 185 MBq [¹⁸F]FDG. For semi-quantitative analysis of [¹⁸F]FDG uptake, standardized uptake values (SUVs) were calculated. Glut-1 expression was studied in terms of the immunohistochemistry of paraffin sections using anti-Glut-1 antibody to determine the intensity (0-3) of Glut-1 immunoreactivity and percentage of the Glut-1-positive area. Of seven bronchioloalveolar carcinomas, six (85.7%) were negative for the expression of Glut-1, while only one (4.3%) of 23 non-bronchioloalveolar adenocarcinomas was negative (P<0.0001). The percentages of Glut-1-positive area, as well as the SUVs, were significantly lower in bronchioloalveolar carcinomas (n=7) (2.86%lj.56% and 1.25ǂ.75, respectively) than in non-bronchioloalveolar adenocarcinomas (n=23) (54.83%ᆭ.64%, P<0.0001, and 3.94ǃ.93, P=0.001, respectively). The degree of cell differentiation correlated with the percentage of Glut-1-positive area and SUVs in adenocarcinoma of the lung. Correlations between SUVs and the intensity of Glut-1 immunoreactivity were also significant (intensities 0 and 1, n=11, SUV 1.47ǂ.63; intensities 2 and 3, n=23, SUV 4.78DŽ.13; P<0.0001). The percentage of Glut-1-positive area correlated significantly with SUVs (n=34, r=0.658, P<0.01). Overexpression of Glut-1 correlated with high [¹⁸F]FDG uptake. These findings suggest that Glut-1 expression is related to [¹⁸F]FDG uptake in non-small cell lung cancer. Glut-1 expression, as well as [¹⁸F]FDG uptake, correlated with the degree of cell differentiation in adenocarcinomas, and both Glut-1 expression and [¹⁸F]FDG uptake were significantly lower in bronchioloalveolar carcinomas than in non-bronchioloalveolar carcinomas.     

Usefulness of CT colonography in the preoperative evaluation of patients with distal occlusive colorectal carcinoma

PURPOSE: To evaluate the role of preoperative virtual colonoscopy to study the proximal colon in patients with distal occlusive carcinomas, diagnosed by conventional colonoscopy. MATERIAL AND METHODS: We examined 19 patients aged 46 to 83 years (13 men and 6 women) with distal occlusive colorectal carcinomas diagnosed by conventional colonoscopy, who were preoperatively studied with virtual colonoscopy. Patients with acute bowel obstruction were excluded. Results were compared with the findings of preoperative conventional colonoscopy and barium enema examination, intraoperative colon palpation, histopathologic outcome, postoperative conventional colonoscopy and barium enema examination. RESULTS: Virtual colonoscopy identified all 19 distal occlusive colon carcinomas and 22 synchronous lesions, 2 cancers (prevalence 10,6%) and 20 polyps (prevalence 68,4%). Both synchronous cancers were confirmed intraoperatively by direct palpation. Postoperative conventional colonoscopy, which was performed in 18 patients, confirmed the presence of 15 polyps in 12 patients. Three subcentimeter polyps were removed during conventional colonoscopy and were missed at virtual colonoscopy. Two polyps shown by virtual colonoscopy were not found at conventional colonoscopy. Postoperative barium enema was performed in three patients and confirmed three polyps identified at virtual colonoscopy. Preoperative barium enema was performed in five patients and failed to adequately demonstrate the proximal colon. Virtual colonoscopy showed a sensitivity of 87% and a specificity of 75%. CONCLUSIONS: Virtual CT colonoscopy can be considered an important diagnostic technique to evaluate preoperatively the proximal colon in patients with distal occlusive carcinomas,as it gives better results than barium enema or conventional colonoscopy, as well as being well tolerated and less invasive.     

Multislice spiral CT colonography in the evaluation of colorectal neoplasms

PURPOSE: The purpose of our study was to evaluate the efficacy of multislice spiral CT colonography: 1) in the diagnosis and staging of colorectal carcinoma; 2) in the evaluation of the proximal colon in patients with stenosing neoplasms. MATERIALS AND METHODS: There were 33 patients (21 males and 12 females) with known colorectal carcinoma diagnosed by conventional colonoscopy. All patients enrolled in the study underwent both conventional colonoscopy followed by CT colonography on the same day. CT examination was performed using a multislice spiral CT scanner (Somatom Plus 4 Volume Zoom; Siemens, Erlangen, Germany). Imaging parameters were: slice collimation, 1 mm; slice thickness, 1 mm; table speed, 8 mm/sec; reconstruction interval, 1 mm; mAs, 80; kVp, 120; acquisition time, 25-32 sec. Image analysis was performed using a software package with volume-rendering capabilities (Vitrea 2.6; Vital Images, Minneapolis, USA). Image analysis consisted in the evaluation of: 1) number, size, and location of the lesions; 2) primary tumor staging. For the purposes of tumor staging, we utilized the TNM staging system. For the evaluation of parameters T and N, histologic examination on resected surgical specimens and lymph nodes served as the standard of reference. The presence of hepatic metastases was confirmed by means of partial surgical resection in patients with single metastasis or by means of intraoperative ultrasonography in patients with multiple metastases. RESULTS: Conventional colonoscopy detected 33 carcinomas and 4 polyps and was incomplete in 9 cases (27.2% of all examinations) due to stenosing lesions. CT colonography provided adequate visualization of the whole colon in all patients with identification of 35 carcinomas (33 primary and 2 synchronous) and 10 polyps. Therefore, CT colonography correctly detected all lesions seen at conventional colonoscopy and yielded the additional identification of 2 synchronous tumors and 6 polyps located in the colon proximal to the primary stenosing neoplasm. Primary tumor staging with CT colonography was correct in 32 of 33 patients (accuracy, 96.9%) CONCLUSIONS: Multislice spiral CT colonography detected all primary neoplasms, provided correct staging of 96.9% of tumors and visualized the whole colon even in patients with stenosing lesions. Considering the current limitations of the other procedures and the possibility of assessing both the colon and the extracolonic structures, multislice spiral CT colonography can be proposed as the initial diagnostic modality for pre-operative evaluation of patients with colorectal carcinoma.     

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.     

The detection of local recurrent head and neck cancer with fluorine-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.     

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.     

PET-FDG as predictor of therapy response in patients with colorectal carcinoma.

AIM: The purpose of this study was to evaluate the prognostic value of quantitative dynamic FDG PET studies in patients with metastastic colorectal cancer receiving FOLFOX (fluorouracil, folinic acid and oxaliplatin) chemotherapy. METHODS: The evaluation includes 28 patients with 55 metastases from primary colorectal cancer. Reference for the FDG studies was the clinical response data, according to the WHO classification. Three response groups were defined: progressive disease (PD), stable disease (SD) and partial response (PR). The FDG studies were accomplished as dynamic series for 60 min. The evaluation of the FDG kinetics was performed using the SUV, and fractal dimension (FD) of the time activity curves based on the box counting procedure (parameter for the inhomogeneity of the tumors). RESULTS: The median SUV as measured in the tumor lesions prior to onset to FOLFOX was 3.15, in comparison with 2.68 SUV after the first cycle and 2.61 SUV after the second cycle. Discriminant analysis (DA) was used for the classification of the data into the 3 categories. Both parameters SUV and FD provided 2 of the 3 "predicted" categories, namely PD and SD. It was possible to correctly classify PR in only 10% of the patients, using the FD of both studies. Generally, DA inclined to misclassify the data towards PD. Even the first PET study was predictive with respect to therapy outcome (96% for PD and 47% for SD using only the baseline SUV). Metastases with a baseline SUV lower than 4.6 did not respond to FOLFOX chemotherapy. The combination of SUV and FD of the first study lead to a correct classification of 93% of PD and 60% of SD. Best results were obtained for the FD of the initial PET study (90% for PD and 75% for SD) as well as for the FD of both studies (77% for PD, 73% for SD, 10% for PR). CONCLUSION: Quantitative, dynamic FDG-PET should be used preferentially for monitoring patients with metastatic colorectal cancer receiving chemotherapy. Even the first FDG study prior to onset to chemotherapy is predictive for the therapy outcome.     

Colorectal polyps: detection with dark-lumen MR colonography versus conventional colonoscopy

PURPOSE: To prospectively compare dark-lumen magnetic resonance (MR) colonography with conventional colonoscopy in the detection of colorectal polyps. MATERIALS AND METHODS: Local ethical committee approval and informed consent were obtained. One hundred consecutive patients (56 men, 44 women; mean age +/- standard deviation, 67.7 years +/- 14.7; range, 25-82 years) who were referred for conventional colonoscopy from January 2003 to January 2004 underwent MR colonography and conventional colonoscopy after standard precolonoscopic bowel cleansing. Colonoscopy was performed immediately after MR colonography. For MR colonography, the colon was filled with approximately 2000 mL of tap water. Imaging was performed with a 1.5-T MR unit with patients in the prone position. A T1-weighted three-dimensional volumetric interpolated breath-hold sequence was performed before and 75 seconds after intravenous administration of 0.2 mmol gadobenate dimeglumine per kilogram of body weight. Results of MR colonography were analyzed on a per-polyp and per-patient basis. Findings at colonoscopy were used as the reference for determining accuracy, sensitivity, specificity, and positive and negative predictive values of MR colonography. RESULTS: Of 100 patients recruited for study, 92 (52 men, 40 women; mean age, 61.5 years +/- 14.5; range, 25-82 years) underwent complete MR and conventional colonoscopy examinations. Forty-three of the 92 patients (47%) had normal findings at conventional colonoscopy. In the other 49 patients (53%), conventional colonoscopy depicted 107 polyps (82 adenomas, 25 hyperplastic polyps) and seven carcinomas. At per-polyp analysis, sensitivity of MR colonography in the detection of adenomatous polyps was 100% for polyps at least 10 mm in diameter and 84.2% for polyps 6-9 mm in diameter. At per-patient analysis, the accuracy of MR colonography was 93.1% (sensitivity, 89%; specificity, 96%) if detection of adenomatous polyps of all sizes was considered. CONCLUSION: Dark-lumen MR colonography is a promising modality with high accuracy for detecting colorectal polyps larger than 5 mm in diameter.