Evaluation of 18F-FDG PET in patients with a, metastatic, or recurrent gastric cancer.

PET with (18)F-FDG has been widely used in oncology, but its application for stomach neoplasms has been limited. The aim of this study was to evaluate the visual diagnostic accuracy of (18)F-FDG PET for advanced, metastatic, or recurrent gastric cancer and to generate semiquantitative values for lesions. METHODS: (18)F-FDG PET scans were obtained on 42 patients (29 men, 13 women; age, 27-78 y; median age, 63 y): 20 patients with a PT931/04 scanner and 22 patients with a SET2400W scanner. The PT931/04 has a spatial resolution of 6.0 mm at full width at half maximum (FWHM) and covers 15 cm above and below the targeted lesion, and the SET2400W has a spatial resolution of 3.9 mm at FWHM and images the entire body. All PET images were interpreted visually, and tracer uptakes were quantitated as standardized uptake values (SUVs) on SET2400W images. RESULTS: The sensitivity, specificity, and accuracy as a whole were as follows: 71%, 74%, and 73%, respectively, with the SET2400W scanner and 47%, 79%, and 62%, respectively, with the PT931/04 scanner. Values were high for primary lesions, liver, lymph node, and lung metastases, but were low for bone metastases, ascites, peritonitis, and pleuritis carcinomatoses. SUVs were 8.9 +/- 4.2 (primary lesions, 19 patients/19 lesions), 6.5 +/- 2.2 (liver, 9/55), 6.1 +/- 2.5 (lymph nodes, 14/38), 6.5 +/- 1.8 (abdominal wall, 4/7), 3.9 +/- 2.0 (bone, 3/27), and 4.7 +/- 2.6 (lung, 2/3). Comparing SUVs and histologic findings for 17 untreated patients, values for well-differentiated and moderately differentiated adenocarcinomas versus poorly differentiated adenocarcinomas and signet ring cell carcinomas were 13.2 +/- 6.3 (4/4) versus 7.7 +/- 2.6 (13/13) (P < 0.05) for the primary lesions, 7.0 +/- 2.4 (5/39) versus 5.6 +/- 2.8 (2/2) for the liver, and 5.5 +/- 1.9 (9/28) versus 8.8 +/- 3.3 (3/8) (P < 0.05) for the lymph nodes. CONCLUSION: Our results indicate that (18)F-FDG PET is a useful diagnostic modality for advanced, metastatic, or recurrent gastric cancer but not for detecting bone metastases, peritonitis, or pleuritis carcinomatoses. (18)F-FDG uptake by gastric cancers is relatively high but does not parallel histopathologic features of malignancy.     

Whole-body 18F-FDG PET in recurrent or metastatic nasopharyngeal carcinoma.

The aim of this retrospective study was to evaluate the sensitivity and prognostic significance of whole-body (18)F-FDG PET for nasopharyngeal carcinoma (NPC) patients for whom there was a suspicion of recurrence or metastasis by conventional radiologic or clinical findings during their follow-up examinations. METHODS: Whole-body (18)F-FDG PET examinations were performed on 64 Taiwanese NPC patients (14 female, 50 male; mean age +/- SD, 45.8 +/- 13.0 y; age range, 16-75 y) 4-70 mo (mean +/- SD, 14.1 +/- 13.5 mo) after radiotherapy or induction chemotherapy followed by concurrent chemoradiotherapy from February 1997 to May 2001. The accuracy of (18)F-FDG PET detection for each patient was determined by the histopathologic results or other clinical evidence. RESULTS: The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of (18)F-FDG PET images in the diagnosis of NPC recurrence or metastases and secondary primary cancers were 92%, 90%, 92%, 90%, and 91%, respectively. Furthermore, the presence of (18)F-FDG hypermetabolism was highly correlated with the survival time of NPC patients. CONCLUSION: Whole-body (18)F-FDG PET is a sensitive follow-up diagnostic tool for the evaluation of NPC recurrences and metastases. It is also an effective prognostic indicator for NPC patients. To determine the optimized utilization of (18)F-FDG PET in the follow-up for NPC patients, further cost-effectiveness analysis of (18)F-FDG PET in combination with conventional management is necessary.     

Complementary roles of 18F-DOPA PET/CT and 18F-FDG PET/CT in medullary thyroid cancer

Serum calcitonin and carcinoembryonic antigen (CEA) are markers of recurrent or persistent disease in medullary thyroid cancer (MTC). However, conventional imaging often fails to localize metastatic disease. Our aim was to compare fluorine-labeled dihydroxyphenylalanine ((18)F-DOPA) and (18)F-FDG PET/CT with multidetector CT (MDCT) and MRI in recurrent or persistent MTC. METHODS: Nineteen MTC patients with increased calcitonin or CEA on follow-up (mean ± SD, 93 ± 91 mo; range, 4-300 mo) after primary therapy were prospectively imaged with 4 techniques: (18)F-DOPA PET/CT, (18)F-FDG PET/CT, MDCT, and MRI. Images were analyzed for pathologic lesions, which were surgically removed when possible. The correlation between the detection rate for each method and the calcitonin and CEA concentrations and histopathologic findings was investigated. Results: On the basis of histology and follow-up, one or more imaging methods accurately localized metastatic disease in 12 (63%) of 19 patients. The corresponding figures for (18)F-DOPA PET/CT, (18)F-FDG PET/CT, MDCT, and MRI were 11 (58%) of 19, 10 (53%) of 19, 9 (47%) of 19, and 10 (59%) of 17, respectively. Calcitonin and CEA correlated with (18)F-DOPA PET/CT (P = 0.0007 and P = 0.0263, respectively) and (18)F-FDG PET/CT findings (both P < 0.0001). In patients with an unstable calcitonin doubling time (n = 8), (18)F-DOPA and (18)F-FDG PET/CT were equally sensitive. In contrast, for patients with an unstable CEA doubling time (n = 4), (18)F-FDG PET/CT was more accurate. CONCLUSION: For most MTC patients with occult disease, (18)F-DOPA PET/CT accurately detects metastases. In patients with an unstable calcitonin level, (18)F-DOPA PET/CT and (18)F-FDG PET/CT are complementary. For patients with an unstable CEA doubling time, (18)F-FDG PET/CT may be more feasible. MRI is sensitive but has the highest rate of false-positive results.     

Therapeutic impact of 18F-FDG PET/CT in recurrent differentiated thyroid carcinoma

Purpose

¹⁸F-fluorodeoxyglucose-positron emission tomography/computed tomography (PET/CT) has proved effective in detecting recurrent or metastatic differentiated thyroid carcinoma (DTC) in the follow-up of operated DTC patients with high thyroglobulin (Tg) levels and negative findings on radioiodine whole-body scan. The aim of this retrospective study was to assess the impact of PET/CT on the planning of appropriate treatment for known recurrent disease in operated DTC patients.

Materials and methods

The study concerned 44 consecutive DTC patients (36 papillary, 8 follicular), who underwent total thyroidectomy and thyroid remnant ablation with ¹³¹I and PET/CT. All patients had proven or strongly suspected recurrent disease judging from neck ultrasound (US) and fine-needle aspiration cytology, and detectable basal Tg levels.

Results

PET/CT findings were positive in 25/44 patients (56.81 %) and negative in 19. A positive PET/CT result predicted resectable tumour recurrences in 19/25 patients, but also detected additional tumour sites that prompted changes to the treatment plan in 6/25 patients (24 %). A negative PET/CT result led to clinical monitoring for 11/19 patients (57.89 %).

Conclusions

PET/CT can help select patients, who might benefit from a tailored therapy by improving the detection of local recurrences not apparent on neck US or metastases.     

^18F-FDG PET／CT显像对肺癌临床治疗决策的影响

目的评价^18F-脱氧葡萄糖（FDG）PET／CT显像对肺癌分期、再分期及临床治疗决策的影响。方法收集2007年7—12月接受PET／CT检查的肺癌或肺癌经过手术、放疗或化疗至少1种治疗的患者为研究对象。通过临床医师填写问卷调查的方法了解患者临床治疗相关资料。PET／CT检查前及检查后问卷资料均齐全的病例为资料完整者。治疗方法主要分为手术、放疗、化疗、随访4种,改变主要分为不同治疗方式间和同一治疗方式内部2种。结果参考PET／CT检查前后问卷情况,资料完整符合要求的病例245例纳入研究进行分析,其中49．8％（122／245）为初次分期,50．2％（123／245）为治疗后再分期或治疗效果评价。PET／CT检查前后临床分期改变为26．5％（65／245）,其中分期上调为17．1％（42／245）,分期下调为9．4％（23／245）,另外还有5．7％（14／245）的病例由于相应临床医师习惯参考PET／CT结果进行分期,故PET／CT检查影响临床分期32．2％（79／245）。PET／CT检查前后治疗方案改变为51．8％（127／245）,不同治疗方式间改变为15．9％（39／245）,同一治疗方式内部改变为35．9％（88／245）。结论^18F-FDG PET／CT显像可提高肺癌临床分期或再分期的准确性,进而影响肺癌临床治疗决策。     

18F-FDG PET/CT显像对肺癌临床治疗决策的影响

目的 评价18F-脱氧葡萄糖(FDG)PET/CT显像对肺癌分期、再分期及临床治疗决策的影响.方法 收集2007年7-12月接受PET/CT检查的肺癌或肺癌经过手术、放疗或化疗至少1种治疗的患者为研究对象.通过临床医师填写问卷调查的方法了解患者临床治疗相关资料.PET/CT检查前及检查后问卷资料均齐全的病例为资料完整者.治疗方法主要分为手术、放疗、化疗、随访4种,改变主要分为不同治疗方式间和同一治疗方式内部2种.结果 参考PET/CT检查前后问卷情况,资料完整符合要求的病例245例纳入研究进行分析,其中49.8%(122/245)为初次分期,50.2%(123/245)为治疗后再分期或治疗效果评价.PET/CT检查前后临床分期改变为26.5%(65/245),其中分期上调为17.1%(42/245),分期下调为9.4%(23/245),另外还有5.7%(14/245)的病例由于相应临床医师习惯参考PET/CT结果进行分期,故PET/CT检查影响临床分期32.2%(79/245).PET/CT检查前后治疗方案改变为51.8%(127/245),不同治疗方式问改变为15.9%(39/245),同一治疗方式内部改变为35.9%(88/245).结论 18F-FDG PET/CT显像可提高肺癌临床分期或再分期的准确性,进而影响肺癌临床治疗决策.     

^18F-FDG PET/CT对可疑复发性宫颈癌的临床价值

目的 探讨^18F-FDG PET/CT在可疑复发性宫颈癌临床诊疗中的价值.方法 回顾性分析51例宫颈癌根治后随访期间临床可疑复发的患者,记录患者的治疗资料、可疑复发表现、18F-FDG PET/CT显像结果、同期常规影像检查结果、病理及临床随访结果、PET/CT结果对临床诊疗的影响.结果 PET/CT诊断宫颈癌复发43例,最终经病理检查及临床随访证实复发性宫颈癌40例,盆腔脓肿2例,放射性肠炎1例;PET/CT未见恶性征象8例,病理检查及临床随访均未见异常.PET/CT诊断复发性宫颈癌灵敏度为100.00%（40/40）,特异性为72.73%（8/11）,准确性为94.12%（48/51）.PET/CT指导制订临床诊疗及随访计划34例,改变治疗计划7例.与其他影像检查相比,PET/CT可发现更多的病灶.结论^18F-FDG PET/CT能有效诊断复发性宫颈癌,指导临床诊疗.     

18F-FDG PET/CT对可疑复发性宫颈癌的临床价值

目的 探讨18F-FDG PET/CT在可疑复发性宫颈癌临床诊疗中的价值.方法 回顾性分析51例宫颈癌根治后随访期间临床可疑复发的患者,记录患者的治疗资料、可疑复发表现、18F-FDG PET/CT显像结果、同期常规影像检查结果、病理及临床随访结果、PET/CT结果对临床诊疗的影响.结果 PET/CT诊断宫颈癌复发43例,最终经病理检查及临床随访证实复发性宫颈癌40例,盆腔脓肿2例,放射性肠炎1例;PET/CT未见恶性征象8例,病理检查及临床随访均未见异常.PET/CT诊断复发性宫颈癌灵敏度为100.00%(40/40),特异性为72.73%(8/11),准确性为94.12%(48/51).PET/CT指导制订临床诊疗及随访计划34例,改变治疗计划7例.与其他影像检查相比,PET/CT可发现更多的病灶.结论 18F-FDG PET/CT能有效诊断复发性宫颈癌,指导临床诊疗.     

Detection of neck recurrence in patients with differentiated thyroid cancer: comparison of ultrasound, contrast-enhanced CT and 18F-FDG PET/CT using surgical pathology as a reference standard: (ultrasound vs. CT vs. 18F-FDG PET/CT in recurrent thyroid cancer)

Objectives

To compare the diagnostic performance of ultrasound, contrast-enhanced computed tomography (CT) and ¹⁸F-FDG positron emission tomography (PET)/CT for detecting recurrent differentiated thyroid cancer in the neck.

Methods

Twenty patients who had undergone previous surgery for differentiated thyroid cancer (19 papillary carcinomas; 1 medullary carcinoma) and presented with pathologically proven recurrence in the neck were included. All patients had undergone ultrasound, CT and PET/CT in the 2 months before further surgery. In each patient, ultrasound, CT and PET/CT images were retrospectively reviewed to determine the presence of loco-regional recurrence by level-by-level analysis. Imaging results were correlated with the histological evaluation of the neck dissection as a standard of reference.

Results

Recurrences were found at 52 out of 110 cervical nodal levels surgically explored. The sensitivity, specificity and accuracy were 69.2 %, 89.7 % and 80.0 % for ultrasound; 63.5 %, 94.8 % and 80.0 % for CT; and 53.8 %, 79.3 % and 67.3 % for PET/CT, respectively. ROC analysis revealed higher diagnostic performance with ultrasound than with PET/CT for detecting recurrent tumour.

Conclusions

Although no significant difference was found among the three techniques, the sensitivity and specificity of ultrasound and CT were higher than those of PET/CT for the evaluation of cervical recurrence in patients with differentiated thyroid cancer.

Key Points

? Ultrasound, CT and ¹⁸ F-FDG PET/CT can all detect recurrent thyroid cancer. ? Ultrasound and CT have higher sensitivity and specificity. ? Ultrasound, CT and ¹⁸ F-FDG PET/CT frequently demonstrated discordant findings     

Comparison of 18F-DOPA, 18F-FDG and 68Ga-somatostatin analogue PET/CT in patients with recurrent medullary thyroid carcinoma

Purpose

To retrospectively evaluate and compare ¹⁸F-FDG, ¹⁸F-DOPA and ⁶⁸Ga-somatostatin analogues for PET/CT in patients with residual/recurrent medullary thyroid carcinoma (MTC) suspected on the basis of elevated serum calcitonin levels.

Methods

Included in the study were 18 patients with recurrent MTC in whom functional imaging with the three tracers was performed. The PET/CT results were compared on a per-patient basis and on a per-lesion-basis.

Results

At least one focus of abnormal uptake was observed on PET/CT in 13 patients with ¹⁸F-DOPA (72.2% sensitivity), in 6 patients with ⁶⁸Ga-somatostatin analogues (33.3%) and in 3 patients with ¹⁸F-FDG (16.7%) (p?18F-DOPA and ¹⁸F-FDG PET/CT (p?18F-DOPA and ⁶⁸Ga-somatostatin analogue PET/CT (p?=?0.04). Overall, 72 lesions were identified on PET/CT with the three tracers. ¹⁸F-DOPA PET/CT detected 85% of lesions (61 of 72), ⁶⁸Ga-somatostatin analogue PET/CT 20% (14 of 72) and ¹⁸F-FDG PET/CT 28% (20 of 72). There was a statistically significant difference in the number of lymph node, liver and bone lesions detected with the three tracers (p?18F-DOPA PET/CT and ¹⁸F-FDG PET/CT (p?18F-DOPA PET/CT and ⁶⁸Ga-somatostatin analogue PET/CT (p?Conclusion ¹⁸F-DOPA PET/CT seems to be the most useful imaging method for detecting recurrent MTC lesions in patients with elevated serum calcitonin levels, performing better than ¹⁸F-FDG and ⁶⁸Ga-somatostatin analogue PET/CT. ¹⁸F-FDG may complement ¹⁸F-DOPA in patients with an aggressive tumour.     

18F-FDG PET/CT在可疑神经系统副肿瘤综合征中的应用价值

目的 探讨18F-脱氧葡萄糖(FDG)PET/CT显像探测临床可疑神经系统副肿瘤综合征(PNS)患者潜在肿瘤病灶的应用价值.方法 回顾性分析20例可疑PNS患者18F-FDG PET/CT显像资料,对所有患者行随访病理检查或临床最终诊断,并将结果与PET/CT显像和随访结果进行比较.结果 20例中PET/CT显像发现可疑恶性病变或既往肿瘤复发和(或)转移者9例,阴性11例.9例阳性者中3例为假阳性.PET/CT显像对PNS恶性肿瘤检出的灵敏度、特异性、准确性、阳性预测值和阴性预测值分别为6/6,78.57%(11/14),85.00%(17/20),6/9和100.00%(11/11).6例真阳性中4例治疗方案得以修正,经抗肿瘤和免疫疗法后神经异常症状得到改善.结论 18F-FDG PET/CT显像在可疑PNS中的应用有积极意义,有助于发现恶性肿瘤,也能对肿瘤分期提供帮助.     

18F-FDG PET/CT在可疑神经系统副肿瘤综合征中的应用价值

目的 探讨18F-脱氧葡萄糖（FDG）PET/CT显像探测临床可疑神经系统副肿瘤综合征（PNS）患者潜在肿瘤病灶的应用价值.方法 回顾性分析20例可疑PNS患者18F-FDG PET/CT显像资料,对所有患者行随访病理检查或临床最终诊断,并将结果与PET/CT显像和随访结果进行比较.结果 20例中PET/CT显像发现可疑恶性病变或既往肿瘤复发和（或）转移者9例,阴性11例.9例阳性者中3例为假阳性.PET/CT显像对PNS恶性肿瘤检出的灵敏度、特异性、准确性、阳性预测值和阴性预测值分别为6/6,78.57%（11/14）,85.00%（17/20）,6/9和100.00%（11/11）.6例真阳性中4例治疗方案得以修正,经抗肿瘤和免疫疗法后神经异常症状得到改善.结论 18F-FDG PET/CT显像在可疑PNS中的应用有积极意义,有助于发现恶性肿瘤,也能对肿瘤分期提供帮助.     

18F-FDG PET/CT在可疑神经系统副肿瘤综合征中的应用价值

目的 探讨18F-脱氧葡萄糖(FDG)PET/CT显像探测临床可疑神经系统副肿瘤综合征(PNS)患者潜在肿瘤病灶的应用价值.方法 回顾性分析20例可疑PNS患者18F-FDG PET/CT显像资料,对所有患者行随访病理检查或临床最终诊断,并将结果与PET/CT显像和随访结果进行比较.结果 20例中PET/CT显像发现可疑恶性病变或既往肿瘤复发和(或)转移者9例,阴性11例.9例阳性者中3例为假阳性.PET/CT显像对PNS恶性肿瘤检出的灵敏度、特异性、准确性、阳性预测值和阴性预测值分别为6/6,78.57%(11/14),85.00%(17/20),6/9和100.00%(11/11).6例真阳性中4例治疗方案得以修正,经抗肿瘤和免疫疗法后神经异常症状得到改善.结论 18F-FDG PET/CT显像在可疑PNS中的应用有积极意义,有助于发现恶性肿瘤,也能对肿瘤分期提供帮助.     

Comparison of the prognostic values of 68Ga-DOTANOC PET/CT and 18F-FDG PET/CT in patients with well-differentiated neuroendocrine tumor

Purpose

To determine the prognostic value of ⁶⁸Ga-DOTANOC PET/CT in patients with well-differentiated neuroendocrine tumor (NET), and to compare the prognostic value with that of ¹⁸F-FDG PET/CT and other conventional clinicopathological prognostic factors.

Methods

Data from 37 consecutive patients (age 46.6?±?13.5 years, 51 % men) with well-differentiated NET who underwent ⁶⁸Ga-DOTANOC PET/CT and ¹⁸F-FDG PET/CT were analyzed. All patients underwent a baseline visit with laboratory and radiological examinations. Clinical and imaging follow-up was performed in all patients. Progression-free survival (PFS) was measured from the date of the first PET/CT scan to the first documentation of progression of disease.

Results

⁶⁸Ga-DOTANOC PET/CT was positive in 37 of the 37 patients and ¹⁸F-FDG PET/CT was positive in 21. During follow-up 10 patients (27 %) showed progression of disease and 27 (73 %) showed no progression (24 stable disease, 3 partial response). The median follow-up was 25 months (range 2 – 52 months). Among the variables evaluated none was significantly different between the progressive disease and nonprogressive disease groups, with only SUVmax on ⁶⁸Ga-DOTANOC PET/CT being borderline significant (P?=?0.073). In the univariate analysis for PFS outcome, SUVmax on ⁶⁸Ga-DOTANOC PET/CT (HR 0.122, 95 % CI 0.019 – 0.779; P?=?0.026) and histopathological tumor grade (HR 4.238, 95 % CI 1.058 – 16.976; P?=?0.041) were found to be associated with PFS. Other factors including age, sex, primary site, Ki-67 index, TNM stage, ¹⁸F-FDG PET/CT status (positive/negative), SUVmax on ¹⁸F-FDG PET/CT and type of treatment were not significant. In multivariable analysis, only SUVmax on ⁶⁸Ga-DOTANOC PET/CT was found to be an independent positive predictor of PFS (HR 0.122, 95 % CI 0.019 – 0.779; P?=?0.026).

Conclusion

SUVmax measured on ⁶⁸Ga-DOTANOC PET/CT is an independent, positive prognostic factor in patients with well-differentiated NET and is superior to SUVmax on ¹⁸F-FDG PET/CT and conventional clinicopathological factors for predicting PFS.     

18F-FDG PET or PET/CT for detection of metastatic lymph nodes in patients with endometrial cancer: A systematic review and meta-analysis

The present study assessed the diagnostic performances of 18F-FDG PET or PET/CT in detecting pelvic and/or paraaortic lymph node metastasis in patients with endometrial cancer. METHODS: Through a search of MEDLINE (January 1998 to March 2011), an overall weighted average for sensitivity and specificity as well as pooled estimates of positive and negative likelihood ratios were calculated. A summary receiver-operating-characteristics (sROC) curve was constructed and the area under the sROC curve (AUC) was calculated. I-square was calculated to explore heterogeneity. RESULTS: The present study included 243 patients from seven studies. Results indicated a lack of significant heterogeneity for sensitivity and specificity (I(2)<50% and p>0.05). The overall pooled estimates for sensitivity and specificity of FDG-PET or PET/CT scans in the detection of pelvic and/or paraaortic metastasis were 63.0% (95% CI, 48.7-75.7%) and 94.7% (95% CI, 90.4-97.4%), respectively. The positive likelihood ratio was 10.465 (95% CI, 5.646-19.396) and the negative likelihood ratio 0.399 (95% CI, 0.284-0.560). The AUC was 0.9533. The overall diagnostic accuracy (Q* index) was 89.5%. Conclusion The high positive likelihood value confirms the reliability of a positive FDG-PET or PET/CT to detect pelvic and/or paraaortic lymph nodes metastasis in patients with untreated endometrial cancer. FDG-PET or PET/CT may prove beneficial to surgeons when selecting appropriate patients on whom to perform lymphadenectomy.     

Usefulness of whole-body (18)F-FDG PET in patients with suspected metastatic brain tumors.

The aim of this study was to evaluate the diagnostic value of whole-body (18)F-FDG PET imaging in the differentiation of metastatic brain tumor from primary brain tumor and in the localization of the primary lesion in patients with metastatic brain tumor. METHODS: The subjects consisted of 127 patients (77 men, 50 women; mean age +/- SD, 55 +/- 12 y) with brain masses that were suspected to be metastatic brain tumors on radiologic studies: 77 with confirmed metastatic brain tumor and 50 with primary brain tumor. Whole-body (18)F-FDG PET was performed on all patients. When the abnormal lesion was detected outside the brain, we interpreted the brain lesion as metastatic brain tumor. RESULTS: In 61 of the 77 patients with metastatic brain tumor, primary lesions were detected using whole-body (18)F-FDG PET. Of the remaining 16 patients (all false-negative cases), 7 were classified as metastases of unknown origin. In 47 of the 50 patients with primary brain tumor, whole-body (18)F-FDG PET did not show any other abnormal lesions. The sensitivity, specificity, positive and negative predictive values, and accuracy of PET for the detection of primary origin were 79.2%, 94.0%, 95.3%, 74.6%, and 85.0%, respectively. The most common primary origin of metastatic brain tumors on PET examination was lung cancer (48/61, 78.7%). The concordance rate between (18)F-FDG PET and conventional radiologic work-up was 80% in identifying primary lesion. Unknown bone or bone marrow metastases and unsuspected distant metastases were found in 14 patients (18%) and 24 patients (31%), respectively, on PET examination. CONCLUSION: Screening the patients with suspected metastatic brain tumors using whole-body (18)F-FDG PET could be helpful in differentiating metastatic brain tumor from primary brain tumor and in detecting the primary lesion.     

18F-FDG hybrid PET in patients with suspected spondylitis

This study investigated the value of fluorine-18 2'-deoxy-2-fluoro- D-glucose (FDG) imaging with a double-headed gamma camera operated in coincidence (hybrid PET) detection mode in patients with suspected spondylitis. Comparison was made with conventional nuclear medicine imaging modalities and magnetic resonance imaging (MRI). Sixteen patients with suspected spondylitis (nine male, seven female, mean age 59 years) prospectively underwent FDG hybrid PET (296 MBq) and MRI. For intra-individual comparison, the patients were also imaged with technetium-99m methylene diphosphonate (MDP) (555 MBq) ( n=13) and/or gallium-67 citrate (185 MBq) ( n=11). For FDG hybrid PET, two or three transverse scans were performed. Ratios of infected (target) to non-infected (background) (T/B) vertebral bodies were calculated. MR images were obtained of the region of interest. Patients found positive for spondylitis with MRI and/or FDG hybrid PET underwent surgical intervention and histological grading of the individual infected foci. Twelve out of 16 patients were found to be positive for spondylitis. Independent of the grade of infection and the location in the spine, all known infected vertebrae ( n=23, 9 thoracic, 12 lumbar, 2 sacral) were detected by FDG hybrid PET. T/B ratios higher than 1.45+/-0.05 (at 1 h p.i.) were indicative of infectious disease, whereas ratios below this value were found in cases of degenerative change. FDG hybrid PET was superior to MRI in patients who had a history of surgery and suffered from a high-grade infection in combination with paravertebral abscess formation ( n=2; further computed tomography was needed) and in those with low-grade spondylitis ( n=2, no oedema) or discitis ( n=2, mild oedema). False-positive 67Ga citrate images ( n=5: 2 spondylodiscitis, 1 aortitis, 1 pleuritis, 1 pulmonary tuberculosis) and 99mTc-MDP SPET ( n=4: 1 osteoporosis, 2 spondylodiscitis, 1 fracture) were equally well detected by FDG hybrid PET and MRI. No diagnostic problems were seen in the other patients ( n=5). In this study, FDG hybrid PET was superior to MRI, 67Ga citrate and (99m)Tc-MDP, especially in patients with low-grade spondylitis (as compared with MRI), adjacent soft tissue infections (as compared with 67Ga citrate) and advanced bone degeneration (as compared with 99mTc-MDP).