Comparison of18FDG-PET with99mTc-HMDP scntigraphy for the detection of bone metastases in patients with breast cancer

OBJECTIVE: Bone is one of the most common sites of metastasis in breast cancer patients. Although bone scintigraphy is widely used to detect metastatic breast cancer, the usefulness of 18FDG-PET for detecting bone metastasis has not been clearly evaluated. The purpose of this study was to compare the diagnostic accuracy of 18FDG-PET with bone scintigraphy in detecting bone metastasis in breast cancer patients. METHODS: Forty-four women aged 35 to 81 years (mean, 56 years) with breast cancer were examined in this study. Both 18FDG-PET and bone scintigraphy were performed for each patient with 0-69 day intervals (mean, 11.5 days). The results of each image interpretation were compared retrospectively. Whole-body bones were classified into 9 anatomical regions. Metastases were confirmed at 45/187 regions in 14 patients by bone biopsy or clinical follow-up including other imaging techniques for a period of at least 6 months afterwards. RESULTS: On a region basis, the sensitivity, specificity, and accuracy of 18FDG-PET were 84%, 99% and 95%, respectively. Although these results were comparable to those of bone scintigraphy, the combination of 18FDG-PET and bone scintigraphy improved the sensitivity (98%) and accuracy (97%) of detection. False negative lesions of bone scintigraphy were mostly bone marrow metastases and those of 18FDG-PET were mostly osteoblastic metastases. 18FDG-PET was superior to bone scintigraphy in the detection of osteolytic lesions (92% vs. 73%), but inferior in the detection of osteoblastic lesions (74% vs. 95%). CONCLUSIONS: This study shows that 18FDG-PET tends to be superior to bone scintigraphy in the detection of osteolytic lesions, but inferior in the detection of osteoblastic lesions. 18FDG-PET should play a complementary role in detecting bone metastasis with bone scintigraphy.     

FDG-PET in a case of multiple bone metastases of gastric cancer

F-18 2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) is useful for surveys to detect bone metastasis because of its greater specificity than bone scintigraphy. However, FDG-PET is also known to yield false-positive results in acute fractures and inflammatory lesions, and distinguishing between benign and malignant lesions is difficult, even when semiquantitative methods are used. We report a case of multiple bone metastases of gastric cancer. One of the bone lesions that was positive for FDG uptake was benign, suggesting that FDG-PET can yield false-positive results.     

Use of a corrected standardized uptake value based on the lesion size on CT permits accurate characterization of lung nodules on FDG-PET

The purpose of this study was to determine the actual standardized uptake value (SUV) by using the lesion size from computer tomography (CT) scan to correct for resolution and partial volume effects in positron emission tomography (PET) imaging. This retrospective study included 47 patients with lung lesions seen on CT scan whose diagnoses were confirmed by biopsy or by follow up CT scan when the PET result was considered negative for malignancy. Each lesion's FDG uptake was quantified by the SUV using two methods: by measuring the maximum voxel SUV (maxSUV) and by using the lesion's size on CT to calculate the actual SUV (corSUV). Among small lesions (2.0 cm or smaller on CT scan), ten were benign and 17 were malignant. The average maxSUV was 1.43+/-0.77 and 3.02+/-1.74 for benign and malignant lesions respectively. When using an SUV of 2.0 as the cutoff to differentiate benignity and malignancy, the sensitivity, specificity, and accuracy were 65%, 70%, and 67% respectively. When an SUV of 2.5 was used for cutoff, the sensitivity, specificity, and accuracy were 47%, 80%, and 59% respectively. The average corSUV was 1.65+/-1.09 and 5.28+/-2.71 for benign and malignant lesions respectively. Whether an SUV of either 2.0 or 2.5 was used for cutoff, the sensitivity, specificity, and accuracy remained 94%, 70%, and 85% respectively. The only malignant lesion that was falsely considered benign with both methods was a bronchioalveolar carcinoma which did not reveal any elevated uptake of fluorine-18 fluorodeoxyglucose (FDG). Of the large lesions (more than 2.0 cm and less than 6.0 cm), one was benign and 19 were malignant and the corSUV technique did not significantly change the accuracy. It is concluded that measuring the SUV by using the CT size to correct for resolution and partial volume effects offers potential value in differentiating malignant from benign lesions in this population. This approach appears to improve the accuracy of FDG-PET for optimal characterization of small lung nodules.     

^18FDG-PET和^99mTc-MDP骨扫描检测骨转移瘤价值的比较

目的:评价18FDG-PET恶性肿瘤骨转移的作用及与99mTc-MDP-ECT 比较.材料和方法: 经病理证实为恶性肿瘤患者51 例及非肿瘤性疾病5例在本科同时接受18F-FDG-PET和99mTc-MDP-ECT检查(时间间隔不超过2周).骨转移的诊断由病理、X线或CT/MRI、随访超过1年综合决定.结果:99mTc-MDP和18FDG-PET 对骨转移瘤诊断的灵敏度、特异性、准确率率分别为93.7%、93.7%,97.5%、50%,90.8%、62.5%.99mTc-MDP和18FDG-PET均为阳性15例,其中证实骨转移为14例,假阳性1例;均为阴性例数为20例.21例不相符的结果中20例99mTc-MDP-ECT 阳性而18F-FDG-PET 为阴性.18F-FDG-PET和99mTc-MDP-ECT假阴性各1例.均诊断为多发骨转移的12例患者中99mTc-MDP-ECT发现的骨转移病灶数多于18F-FDG-PET.结论:18F-FDG-PET 与99mTc-MDP骨扫描相比较对肿瘤骨转移的探测有较高的特异性,但敏感性较低.     

肺癌脊柱骨转移ECT检查76例分析

目的:探讨肺癌脊柱骨转移患者全身静态骨显像(ECT)的特点及规律。方法:收集用ECT检查发现的35~85岁肺癌脊柱骨转移76例患者临床资料,将其分为49岁以下组及50岁以上组(包括50岁),分析其临床特点及ECT表现,并结合X线检查结果分析其早期诊断优势。结果:50岁以上组61例,占80.3%;49岁以下组15例,占19.7%;76例脊柱转移患者中50例为多发病灶(占65.8%),26例为单发病灶(占34.2%)。转移灶尤以胸腰椎最多见。全组病例的78.9%表现为溶骨性破坏,14.5%表现为蜂窝状溶骨性骨破坏,5.3%表现为小片状、斑片状成骨性改变,1.3%表现为斑片状溶骨及成骨混合性改变。结论:肺癌脊柱骨转移的发生有一定的规律及特点,较之X线检查,核素全身骨显像对于肺癌脊柱骨转移的早期临床诊断及治疗决策有重要的意义。     

Fluoro-deoxy-glucose positron emission tomography for evaluation of indeterminate lung nodules: assigning a probability of malignancy may be preferable to binary readings

OBJECTIVE: To assess the diagnostic value of fluorine-18 fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) using standard uptake values (SUV) in the differential diagnoses of indeterminate pulmonary nodules. Specifically, we assessed the probability of malignancy for various SUV ranges, and compared the diagnostic efficacy of SUV with and without correction for partial volume effects on the basis of lesion size. METHODS: The FDG-PET scans performed on 158 patients with biopsy-proven pulmonary lesions seen on computed tomography (CT) scan were retrospectively reviewed. Histopathological confirmation was obtained to establish the diagnosis of the lesions. A region of interest (ROI) was drawn for each lesion, and FDG uptake was quantified (SUV(raw)). The SUV(raw) values were normalized for the "size" of the pulmonary lesions measured on CT (SUV(size)). Sensitivity and specificity of FDG-PET for pulmonary lesions <2 cm in diameter or > or =2 cm in diameter were determined at SUV cutoff values of 2.5. The areas under the receiver-operating characteristic (ROC) curve for SUV(raw) and SUV(size) regarding the presence of malignancy were compared for statistical differences. The frequency of malignant lesions for each range of SUVs was obtained to produce the probability of cancer (POC). RESULTS: The mean SUV(raw) was 3.17 +/- 2.76 and 9.18 +/- 6.72 for benign and malignant lesions, respectively. When a SUV(raw) value of 2.5 was used as a cutoff, sensitivity and specificity were 89% and 51%, respectively, for all lesion sizes. The sensitivity and specificity at a cutoff SUV(raw) of 2.5 for lesions less than 2 cm in diameter were 75% and 72%, respectively, and 92% and 41% for lesions 2 cm or greater, respectively. The sensitivity and specificity at a cutoff SUV(size) of 2.5 were 88% and 42%, respectively. The area under the ROC curves for SUV(raw) and SUV(size) was 0.816 and 0.743, respectively (P value 0.034). When the SUV(raw) was divided into three groups, the probability of malignancy was 26% when the SUV(raw) was <2, 57% for 2 < or = SUV(raw) < 6, and 89% for SUV(raw) > or = 6. CONCLUSIONS: The FDG-PET is a reasonably accurate and useful tool for characterizing the nature of indeterminate pulmonary lesions, although the specificity was not as high as that reported in the literature, probably owing in part to our patient population and selection bias. Our data suggest that reporting the results of PET studies as a probability rather than as positive or negative for malignancy would be more useful for further management decision making. Correction of SUVs for tumor size did not improve accuracy.     

Pitfalls of FDG-PET for the diagnosis of osteoblastic bone metastases in patients with breast cancer

Purpose The purpose of this study was to investigate the pitfalls of using 2-[¹⁸F]-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) for the evaluation of osteoblastic bone metastases in patients with breast cancer by comparing it with ^99mTc-hydroxymethylene diphosphonate bone scintigraphy.Methods Among the 89 breast cancer patients (mean age 59±15 years) who had undergone both FDG-PET and bone scintigraphy within 1 month between September 2003 and December 2004, 55 with bone metastases were studied. The bone metastases were visually classified by multi-slice CT into four types according to their degree of osteosclerosis and osteolysis—osteoblastic, osteolytic, mixed and invisible—and compared in terms of tracer uptake on FDG-PET or bone scintigraphy and SUV_mean on FDG-PET. Differences in the rate of detection on bone scintigraphy and FDG-PET were analysed for significance by the McNemar test.Results The sensitivity, specificity and accuracy of bone scintigraphy were 78.2%, 82.4% and 79.8% respectively, and those of FDG-PET were 80.0%, 88.2% and 83.1%, respectively, revealing no significant differences. According to the CT image type, the visualisation rate of bone scintigraphy/FDG-PET was 100%/55.6% for the blastic type, 70.0%/100.0% for the lytic type, 84.2%/94.7% for the mixed type and 25.0%/87.5% for the invisible type. The visualisation rates of bone scintigraphy for the blastic type and FDG-PET for the invisible type were significantly higher. The SUV_mean of the blastic, lytic, mixed and invisible types were 1.72±0.28, 4.14±2.20, 2.97±1.98 and 2.25±0.80, respectively, showing that the SUV_mean tended to be higher for the lytic type than for the blastic type.Conclusion FDG-PET showed a low visualisation rate in respect of osteoblastic bone metastases. Although FDG-PET is useful for detection of bone metastases from breast cancer, it is apparent that it suffers from some limitations in depicting metastases of the osteoblastic type.An editorial commentary on this paper is available at     

Diagnostic performance of PET/CT in differentiation of malignant and benign non-solid solitary pulmonary nodules

OBJECTIVE: To evaluate whether [F-18] fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) can distinguish benign from malignant solitary pulmonary nodules (SPNs) with non-solid components. METHODS: [F-18] FDG-PET/CT scans were performed on 53 consecutive patients (30 men, 23 women; mean age 65 years) who had SPNs with non-solid components identified by CT screening for lung cancer. All patients underwent surgical resection, and all lesions were pathologically proved. Visual score, maximal, and mean standardized uptake value (SUV), and maximal and mean lesion-to-normal tissue count density ratio (LNR) were calculated in all lesions. In addition, clinical characteristics, laboratory test results, and CT findings were assessed. RESULTS: Benign SPNs with non-solid components had a higher uptake on [F-18] FDG-PET/CT. Visual score, maximal and mean SUV, and maximal and mean LNR were significantly higher in the benign when compared with the malignant SPNs (P < 0.001). When the cutoff of 1.5 was assigned for maximal SUV, the diagnostic performance of [F-18] FDG-PET/CT in predicting benign SPN revealed 100.0% sensitivity, 96.4% specificity, and 100.0% accuracy. CONCLUSIONS: [F-18] FDG-PET/CT is useful for the differential diagnosis of SPNs with non-solid components.     

Comparison of bone single-photon emission tomography and planar imaging in the detection of vertebral metastases in patients with back pain

Bone scan has long been considered to be an important diagnostic test in searching for bone metastases. However, considerable difficulty is encountered in the vertebral region due to the complexity of structures and the fact that other benign lesions, especially degenerative changes, are very common there. Single-photon emission tomography (SPET) has been reported to be useful in the differentiation of benign from malignant conditions. Here we report our experience with bone SPET in the diagnosis of vertebral metastases. This is a retrospective study of technetium-99m methylene diphosphonate (MDP) bone scans in 174 consecutive patients who were referred for the investigation of back pain in our department. MDP planar and SPET images were obtained. Of teh 174 patients, 98 had a known history of malignant tumours. The diagnosis of vertebral metastasis was made on the basis of the patients’ clinical histories and the findings with other imaging techniques such as magnetic resonance imaging, computed tomography or follow-up bone scan. We found that the presence of pedicle involvement as seen on SPET was an accurate diagnostic criterion of vertebral metastasis. SPET had a sensitivity of 87%, a specificity of 91%, a positive predictive value of 82%, a negative predictive value of 94% and an accuracy of 90%. On the other hand, planar study had a sensitivity of 74%, a specificity of 81%, a positive predictive value of 64%, a negative predictive value of 88% and an accuracy of 79% in diagnosing vertebral metastasis. Except with regard to the negative predictive value, SPET performed statistically better than planar imaging. Only 9/147 (6.4%) lesions involving the vertebral body alone and 3/49 (6.1%) lesions involving facet joints alone were subsequently found to be metastases. We conclude that bone SPET is an accurate diagnostic test for the detection of vertebral metastases and is superior to planar imaging in this respect. Received 20 December 1997 and in revised form 16 March 1998     

Comparison of FDG PET and SPECT for detection of bone metastases in breast cancer

OBJECTIVE: The purpose of our study was to evaluate the efficacy of FDG PET and bone SPECT for diagnosing bone metastases in breast cancer. SUBJECTS AND METHODS: The study was a prospective series of 15 patients with breast cancer who underwent both PET and bone scanning with SPECT. Comparison was performed on a lesion-by-lesion analysis. MDCT, MRI, and the patient's clinical course were used as references. RESULTS: In the lesion-by-lesion analysis (n = 900), the sensitivity for diagnosing bone metastases was 85% for SPECT and 17% for PET, specificity was 99% for SPECT and 100% for PET, and accuracy was 96% for SPECT and 85% for PET. In the statistical analysis, bone SPECT was significantly superior to FDG PET for its sensitivity (p < 0.0001) and accuracy (p < 0.0001). No statistically significant difference was seen with regard to specificity. When classifying the bone metastases as osteoblastic or osteolytic, bone scanning classified 92% of metastases as osteoblastic and 35% of metastases as osteolytic, whereas PET classified 6% of metastases as osteoblastic and 90% of metastases as osteolytic. CONCLUSION: Bone SPECT is superior to FDG PET in detecting bone metastases in breast cancer. The sensitivity of osteoblastic lesions is limited with FDG PET. Surveillance of metastatic spread to the skeleton in breast cancer patients based on FDG PET alone is not possible.     

Detection of bone metastases in breast cancer by positron emission tomography

Positron emission tomography (PET) is able to demonstrate changes in the metabolism of malignant tumors and metastases before they become visible on anatomical imaging. The skeleton is the most common site of distant metastases of breast cancer. There is convincing evidence that FDG-PET is more sensitive in detecting osteolytic metastases than bone scintigraphy, whereas bone scintigraphy is more sensitive in detecting osteoblastic metastases. Because both types of metastases can occur in breast cancer, bone scintigraphy and FDG-PET should be considered as complementary and can currently be regarded as standard of care for staging in breast cancer patients, whereas the decision to use F-18 fluoride PET should be made individually for each patient, depending on the expected change of therapy management.     

Assessment of local control after laser-induced thermotherapy of liver metastases from colorectal cancer: contribution of FDG-PET in patients with clinical suspicion of progressive disease

BACKGROUND: Management of patients after locally ablative treatment of liver metastases requires exact information about local control and systemic disease status. To fulfill these requirements, whole-body imaging using positron emission tomography with (18)F-fluorodeoxyglucose (FDG-PET) is a promising alternative to morphologic imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI). PURPOSE: To evaluate FDG-PET for the assessment of local control and systemic disease in patients with clinical suspicion of tumor progression after laser-induced thermotherapy (LITT) of colorectal liver metastases. MATERIAL AND METHODS: In 21 patients with suspicion of progressive disease after LITT, whole-body FDG-PET was performed. The presence of viable tumor within treated lesions, new liver metastases, and extrahepatic disease was evaluated visually and semiquantitatively (maximal standard uptake value [SUV(max)], tumor-to-normal ratio [T/N]). The standard of reference was histopathology (n = 25 lesions) and/or clinical follow-up (>12 months) including contrast-enhanced MRI of the liver. RESULTS: Among 54 metastases treated with LITT, 29 had residual tumor. Receiver operating characteristic (ROC) analysis of SUV(max) (area under the curve (AUC) 0.990) and T/N (AUC 0.968) showed a significant discrimination level of negative or positive lesion status with an equal accuracy of 94% (51/54). The overall accuracy of visual FDG-PET was 96% (52/54), with one false-negative lesion among six examined within 3 days after LITT, and one false-positive lesion examined 54 days after LITT. In the detection of new intra- and extrahepatic lesions, FDG-PET resulted in correct alteration of treatment strategy in 43% of patients (P = 0.007). CONCLUSION: FDG-PET is a promising tool for the assessment of local control and whole-body restaging in patients with clinical suspicion of tumor progression after locally ablative treatment of colorectal liver metastases with LITT.     

FDG-PET and CT patterns of bone metastases and their relationship to previously administered anti-cancer therapy

Purpose To assess ¹⁸F-fluorodeoxyglucose (FDG) uptake in bone metastases in patients with and without previous treatment, and compare positive positron emission tomography (PET) with osteolytic or osteoblastic changes on computed tomography (CT).Methods One hundred and thirty-one FDG-PET/CT studies were reviewed for bone metastases. A total of 294 lesions were found in 76 patients, 81 in untreated patients and 213 in previously treated patients. PET was assessed for abnormal FDG uptake localised by PET/CT to the skeleton. CT was evaluated for bone metastases and for blastic or lytic pattern. The relationship between the presence and pattern of bone metastases on PET and CT, and prior treatment was statistically analysed using the chi-square test.Results PET identified 174 (59%) metastases, while CT detected 280 (95%). FDG-avid metastases included 74/81 (91%) untreated and 100/213 (47%) treated lesions (p<0.001). On CT there were 76/81 (94%) untreated and 204/213 (96%) treated metastases (p NS). In untreated patients, 85% of lesions were seen on both PET and CT (26 blastic, 43 lytic). In treated patients, 53% of lesions were seen only on CT (95 blastic, 18 lytic). Of the osteoblastic metastases, 65/174 (37%) were PET positive and 98/120 (82%), PET negative (p<0.001).Conclusion The results of the present study indicate that when imaging bone metastases, prior treatment can alter the relationship between PET and CT findings. Most untreated bone metastases are PET positive and lytic on CT, while in previously treated patients most lesions are PET negative and blastic on CT. PET and CT therefore appear to be complementary in the assessment of bone metastases.     

FDG-PET for detection of osseous metastases from malignant primary bone tumours: comparison with bone scintigraphy

The purpose of this study was to compare positron emission tomography using fluorine-18 fluorodeoxyglucose (FDG-PET) and technetium-99m methylene diphosphonate (MDP) bone scintigraphy in the detection of osseous metastases from malignant primary osseous tumours. In 70 patients with histologically proven malignant primary bone tumours (32 osteosarcomas, 38 Ewing's sarcomas), 118 FDG-PET examinations were evaluated. FDG-PET scans were analysed with regard to osseous metastases in comparison with bone scintigraphy. The reference methods for both imaging modalities were histopathological analysis, morphological imaging [additional conventional radiography, computed tomography (CT) or magnetic resonance imaging (MRI)] and/or clinical follow-up over 6-64 months (median 20 months). In 21 examinations (18%) reference methods revealed 54 osseous metastases (49 from Ewing's sarcomas, five from osteosarcomas). FDG-PET had a sensitivity of 0.90, a specificity of 0.96 and an accuracy of 0.95 on an examination-based analysis. Comparable values for bone scintigraphy were 0.71, 0.92 and 0.88. On a lesion-based analysis the sensitivity of FDG-PET and bone scintigraphy was 0.80 and 0.72, respectively. Analysing only Ewing's sarcoma patients, the sensitivity, specificity and accuracy of FDG-PET and bone scan were 1.00, 0.96 and 0.97 and 0.68, 0.87 and 0.82, respectively (examination-based analysis). None of the five osseous metastases from osteosarcoma were detected by FDG-PET, but all of them were true-positive using bone scintigraphy. In conclusion, the sensitivity, specificity and accuracy of FDG-PET in the detection of osseous metastases from Ewing's sarcomas are superior to those of bone scintigraphy. However, in the detection of osseous metastases from osteosarcoma, FDG-PET seems to be less sensitive than bone scintigraphy.     

Sensitivity in detecting osseous lesions depends on anatomic localization: planar bone scintigraphy versus 18F PET.

Radionuclide bone scanning (RNB) is considered to be the most practical screening technique for assessing the entire skeleton for skeletal metastases. However, RNB has been shown to be of lower sensitivity than MRI and CT in detecting osteolytic metastases. A prospective study was designed to evaluate the accuracy of planar RNB versus tomographic bone imaging with 18F-labeled NaF and PET (18F PET) in detecting osteolytic and osteoblastic metastases and its dependency on their anatomic localization. METHODS: Forty-four patients with known prostate, lung or thyroid carcinoma were examined with both planar RNB and 18F PET. A panel of reference methods including MRI of the spine, 1311 scintigraphy, conventional radiography and spiral CT was used as the gold standard. RNB and 18F PET were compared by a lesion-by-lesion analysis using a five-point score for receiver operating characteristic (ROC) curve analysis. RESULTS: 18F PET showed 96 metastases (67 of prostate carcinoma and 29 of lung or thyroid cancer), whereas RNB revealed 46 metastases (33 of prostate carcinoma and 13 of lung or thyroid cancer). All lesions found with RNB were also detected with 18F PET. Compared with 18F PET and the reference methods, RNB had a sensitivity of 82.8% in detecting malignant and benign osseous lesions in the skull, thorax and extremities and a sensitivity of 40% in the spine and pelvis. The area under the ROC curve was 0.99 for 18F PET and 0.64 for RNB. CONCLUSION: 18F PET is more sensitive than RNB in detecting osseous lesions. With RNB, sensitivity in detecting osseous metastases is highly dependent on anatomic localization of these lesions, whereas detection rates of osteoblastic and osteolytic metastases are similar. Higher detection rates and more accurate differentiation between benign and malignant lesions with 18F PET suggest the use of 18F PET when possible.     

The benefit of SPECT when added to planar scintigraphy in patients with bone metastases in the spine.

PURPOSE: This study compared the efficiency of SPECT with planar bone scans in differentiating malignant from benign lesions and in detecting metastases to the spine. METHODS: Planar scintigraphy and SPECT were performed in 37 patients with low back pain without known malignancy and in 38 patients with confirmed malignancy. The type, location, and intensity of tracer accumulation were compared on the planar and SPECT scans. The malignant or benign nature of lesions was proved by radiologic methods, histologic findings, 6 month follow-up, or all of these. RESULTS: More metastases were detected by SPECT (SPECT, 58 of 64; planar, 42 of 64; P < 0.01). In three of seven patients with known malignancy who had a normal result of planar scan, only SPECT detected metastases. Fifty-nine metastases were radiologically mainly osteolytic, one was osteoblastic and four were mixed. Most lesions showed increased radioactivity (40 of 42 on planar scans vs. 45 of 58 on SPECT) and 2 of 42 (5%) vs. 12 of 58 (21%) were cold with marginally increased uptake. One of 58 metastases was a cold lesion seen on SPECT only. Lesions were more often malignant than benign when seen on SPECT in a pedicle (n = 5; malignant = 3, benign = 2), in the body and pedicle (n = 22; malignant = 14, benign = 8), within the vertebral body (n = 5; malignant = 4, benign = 1) and in the whole vertebra (n = 6; malignant = 4, benign = 2). The lesion to background ratio was higher on SPECT than on planar scans (SPECT, 2.26; planar scans, 1.86; P < 0.05 in malignant lesions). CONCLUSIONS: SPECT of the spine improved the diagnostic accuracy of bone scans when added to a planar scan in patients with known malignancy and clinical suspicion of spinal metastases when the planar scan was borderline abnormal. It helps in differentiating between benign and malignant lesions of the spine.     

FDG-PET for detection of osseous metastases from malignant primary bone tumours: comparison with bone scintigraphy

The purpose of this study was to compare positron emission tomography using fluorine-18 fluorodeoxyglucose (FDG-PET) and technetium-99m methylene diphosphonate (MDP) bone scintigraphy in the detection of osseous metastases from malignant primary osseous tumours. In 70 patients with histologically proven malignant primary bone tumours (32 osteosarcomas, 38 Ewing's sarcomas), 118 FDG-PET examinations were evaluated. FDG-PET scans were analysed with regard to osseous metastases in comparison with bone scintigraphy. The reference methods for both imaging modalities were histopathological analysis, morphological imaging [additional conventional radiography, computed tomography (CT) or magnetic resonance imaging (MRI)] and/or clinical follow-up over 6-64 months (median 20 months). In 21 examinations (18%) reference methods revealed 54 osseous metastases (49 from Ewing's sarcomas, five from osteosarcomas). FDG-PET had a sensitivity of 0.90, a specificity of 0.96 and an accuracy of 0.95 on an examination-based analysis. Comparable values for bone scintigraphy were 0.71, 0.92 and 0.88. On a lesion-based analysis the sensitivity of FDG-PET and bone scintigraphy was 0.80 and 0.72, respectively. Analysing only Ewing's sarcoma patients, the sensitivity, specificity and accuracy of FDG-PET and bone scan were 1.00, 0.96 and 0.97 and 0.68, 0.87 and 0.82, respectively (examination-based analysis). None of the five osseous metastases from osteosarcoma were detected by FDG-PET, but all of them were true-positive using bone scintigraphy. In conclusion, the sensitivity, specificity and accuracy of FDG-PET in the detection of osseous metastases from Ewing's sarcomas are superior to those of bone scintigraphy. However, in the detection of osseous metastases from osteosarcoma, FDG-PET seems to be less sensitive than bone scintigraphy.     

The influence of I-131 therapy on FDG uptake in differentiated thyroid cancer

OBJECTIVE: 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) [or PET/computed tomography (CT)] is more likely to show false-negative results when it is performed shortly after chemotherapy and/or radiotherapy because of "metabolic stunning". The present study aimed to evaluate the influence of I-131 therapy on FDG uptake and the detection of recurrence or metastasis of differentiated thyroid cancer (DTC). METHODS: We retrospectively enrolled 16 consecutive FDG-PET/CT studies which had been performed in patients with DTC with elevated thyroglobulin (TG) but negative I-131 whole-body scan. All studies were performed under L: -thyroxine suppression. The patients were divided into groups A and B for PET/CT performed within 4 months of I-131 therapy or no such therapy, respectively. Each lesion identified on PET/CT was characterized using a 5-point scale by visual analysis: 0 = definitely benign, 1 = probably benign, 2 = equivocal, 3 = probably malignant, and 4 = definitely malignant. The maximum standardized uptake value (SUV max) in each lesion was also measured for semiquantitative analysis. We compared the visual grading and SUV max of the lesion of highest FDG uptake between groups A and B. RESULTS: For visual analysis, group B had significantly more patients with an uptake score of 3 or 4 than group A (80% vs. 17%, P = 0.01). In addition, there were significantly more equivocal results from group A than from group B (67% vs. 10%, P = 0.02). If the patients with the highest uptake scores of 2, 3, and 4 were considered to be positive for local recurrence or metastasis, there would be no significant difference between the positive rates of groups A and B (83% vs. 90%, P = 0.7). However, the mean SUV max of positive results was significantly lower for group A than for group B (3.1 +/- 0.9 and 6.6 +/- 3.5, respectively, P = 0.02). CONCLUSIONS: The preliminary results suggested that FDG uptake in DTC may be negatively influenced by I-131 therapy within 4 months, resulting in lower FDG uptake and more equivocal results. Further studies are necessary to determine whether it is secondary to "metabolic stunning" caused by I-131 therapy.     

Whole body PET for the evaluation of bony metastases in patients with breast cancer: comparison with 99Tcm-MDP bone scintigraphy

The purpose of this study was to determine the potential role of positron emission tomography (PET) using 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) for the evaluation of bony metastasis compared with 99Tcm-methylene diphosphonate (99Tcm-MDP) bone scintigraphy in patients with breast cancer. Fifty-one female patients with breast cancer who had PET together with a bone scan within 1 month between September 1994 and March 1997 were included in this study. The median age was 49 years (range 29-79 years). The sensitivity, specificity and accuracy of the bone scan were 77.7%, 80.9% and 80.3%, respectively. On the other hand, for the detection of bone metastases PET had a sensitivity, specificity and accuracy of 77.7%, 97.6% and 94.1%, respectively. In the diagnosis of bony metastasis derived from breast cancer, FDG-PET was statistically superior to bone scintigraphy in its specificity. In conclusion, FDG-PET appears to be a powerful tool not only in the diagnosis of the primary lesion and soft tissue metastasis, but also in the diagnosis of bony metastasis among patients with breast cancer.     

Use of FDG-PET in differentiating benign from malignant compression fractures

Objective The objective was to evaluate the use of fluorodeoxyglucose positron emission tomography (FDG-PET) in differentiating benign from malignant compression fractures. Patients and methods In a retrospective analysis, we identified 33 patients with 43 compression fractures who underwent FDG-PET. On FDG-PET the uptake pattern was recorded qualitatively and semiquantitatively and fractures were categorized as benign or malignant. Standardized uptake values (SUV) were obtained. MRI, CT, and biopsy results as well as clinical follow-up for 1–3 years served as standards of reference. The Student’s t test was used to determine whether there was a statistically significant difference between the SUV for benign and malignant compression fractures. Results There were 14 malignant and 29 benign compression fractures, including 5 acute benign fractures. On FDG-PET, 5 benign fractures were falsely classified as malignant (false-positive). Three of these patients underwent prior treatment with bone marrow-stimulating agents. There were two false-negative results. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of FDG-PET in differentiating benign from malignant compression fractures were 86%, 83%, 84%, 71%, and 92% respectively. The difference between SUV values of benign and malignant fractures was statistically significant (1.9 ± 0.97 for benign and 3.9 ± 1.52 for malignant fractures, p < 0.001). SUV of benign acute and chronic fractures were not statistically significant. Conclusion Fluorodeoxyglucose positron emission tomography is useful in differentiating benign from malignant compression fractures. Therapy with bone marrow-stimulating agents can mimic malignant involvement.