The role of <Superscript>18</Superscript>F-fluorodeoxyglucose uptake of bone marrow on PET/CT in predicting clinical outcomes in non-small cell lung cancer patients treated with chemoradiotherapy

Objectives

This study aimed to assess the relationship between bone marrow (BM) FDG uptake on PET/CT and serum inflammatory markers and to evaluate the prognostic value of BM FDG uptake for predicting clinical outcomes in non-small cell lung cancer (NSCLC) patients.

Methods

One hundred and six NSCLC patients who underwent FDG PET/CT for staging work-up and received chemoradiotherapy were enrolled. Mean BM FDG uptake (BM SUV) and BM-to-liver uptake ratio (BLR) were measured, along with volumetric parameters of PET/CT. The relationship of BM SUV and BLR with hematologic parameters and serum inflammatory markers was evaluated. Prognostic values of BM SUV and BLR for predicting progression-free survival (PFS) and overall survival (OS) were assessed.

Results

BM SUV and BLR were significantly correlated with white blood cell count and C-reactive protein level. On univariate analysis, BLR was a significant prognostic factor for both PFS and OS. On multivariate analysis, TNM stage and BLR were independent prognostic factors for PFS, and only TNM stage was an independent prognostic factor for OS.

Conclusions

In NSCLC patients, FDG uptake of BM reflects the systemic inflammatory response and can be used as a biomarker to identify patients with poor prognosis.

Key Points

? Bone marrow FDG uptake is correlated with serum inflammatory markers. ? Bone marrow FDG uptake is an independent prognostic factor for progression-free survival. ? Bone marrow FDG uptake can provide information on predicting lung cancer progression.

     

Cystic Fibrosis: Detecting Changes in Airway Inflammation with FDG PET/CT

Purpose: To determine if fluorine 18 fluorodeoxyglucose (FDG) positron emission tomographic (PET)/computed tomographic (CT) imaging can depict a treatment effect from intravenous antibiotics for pulmonary exacerbation in cystic fibrosis (CF). Materials and Methods: The study was approved by the institutional review board of the Hospital for Sick Children and by Health Canada. Consent was obtained from all subjects. Patients with CF who were between 6 and 18 years of age and were admitted for a pulmonary exacerbation were eligible for the study. FDG PET/CT examinations (with low-dose CT) were performed on days 1 and 14 of admission (±72 hours). PET activity was quantified by using standardized uptake values (SUVs) through assessment of background activity (mean SUV [SUV(mean)]) and superimposed focal uptake (maximum SUV [SUV(max)]) for each lung zone. CT studies were scored by using the CF-CT model. SUVs from pre- and posttherapy studies were compared by using paired t tests. Unpaired t tests were used to compare data in patients with CF and data in 10 control subjects. Results: Twenty patients with CF were enrolled. Antibiotic therapy resulted in a significant decrease in SUV(max) (mean difference, 2.3 ± 2.1 [standard deviation], P < .0001). Pretherapy SUV(max) and SUV(mean) and posttherapy SUV(max) were significantly different from those in control subjects. The change in SUV(max) and percentage predicted forced expiratory volume in 1 second was negatively correlated. (R = -0.72, P = .004). Overall CF-CT scores significantly correlated with SUV(max) (R = 0.40, P = .01). Conclusion: FDG PET/CT is a useful tool for detecting inflammatory changes resulting from treatment for pulmonary exacerbations in pediatric patients with CF. Inflammatory changes detected by using FDG PET/CT correlated with lung function, sputum neutrophil counts, and CF-CT scores. Analyzing focal lung inflammation (with SUV(max)) may be a feasible way to measure airway inflammation in patients with CF. ? RSNA, 2012 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12111873/-/DC1.     

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.     

Prognostic value of FDG uptake by the bone marrow in squamous cell carcinoma of the head and neck

BACKGROUND: The appearance of natural suppressor cells and circulating endothelial progenitor cells in tumour tissue has been associated with myelopoetic stimulation by growth factors that may increase fluorodeoxyglucose (FDG) uptake by the bone marrow and high FDG uptake by bone marrow in patients suffering from human malignancies is a not uncommon finding. METHODS: This study looked at the relationship between bone marrow FDG uptake, biochemical (Hb level, RBC count, WBC count and platelet count), clinical and radiological findings and outcome in a series of 35 patients suffering from squamous cell carcinoma of the head and neck (SCCHN), consecutively referred for FDG PET as part of their routine staging procedure. RESULTS AND CONCLUSION: In SCCHN, mean FDG standardized uptake values (SUVs) of the primary tumour correlate significantly with blood WBC count (r=0.44; P=0.011, Bonferroni corrected P=0.04) and mean FDG SUVs of bone marrow are significantly correlated to the maximum FDG SUVs of the primary tumour (r=0.523; P=0.002). Finally, FDG uptake by the bone marrow is related to disease-free and overall survival. These findings warrant confirmation in a larger patient series.     

Focal uptake of fluorodeoxyglucose by the thyroid in patients undergoing initial disease staging with combined PET/CT for non-small cell lung cancer

PURPOSE: To retrospectively evaluate the prevalence of focal fluorodeoxyglucose (FDG) uptake by the thyroid gland on combined positron emission tomographic (PET) and computed tomographic (CT) scans in patients undergoing staging of newly diagnosed non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: Institutional review board approval was obtained, informed consent was waived, and the study was Health Insurance Portability and Accountability Act-compliant. Whole-body PET/CT scans and medical records of 140 consecutive patients with newly diagnosed NSCLC (80 men, 60 women; mean age, 66 years; range, 39-89 years) were retrospectively reviewed by two experienced PET/CT scan readers. Maximum standardized uptake value (SUV) was calculated for FDG-avid thyroid foci. Corresponding thyroid CT findings were recorded in patients with focal increased FDG thyroid uptake. RESULTS: PET results showed that six patients (4.3%) had seven foci of increased FDG uptake in the thyroid. Five of the seven foci (in four patients) corresponded to a low-attenuation thyroid lesion on the non-enhanced CT scan. Lesions ranged in diameter from 0.8 to 2.5 cm. Four of the lesions were found to be papillary thyroid cancers at fine-needle aspiration biopsy. The fifth lesion was found to be benign at thyroidectomy. The remaining two patients did not have histologic confirmation of their thyroid lesion because no specific biopsy site was visualized on CT or sonographic images and lesions were considered benign. Maximum SUV of the thyroid cancers ranged from 3.0 to 32.9 (mean, 13.7). Maximum SUV of benign thyroid lesions ranged from 4.6 to 6.2 (mean, 5.4). CONCLUSION: Focal thyroid FDG uptake found during the initial staging of NSCLC at PET/CT indicates a high likelihood of primary thyroid cancer.     

Optimal interpretation of FDG PET in the diagnosis, staging and management of pancreatic carcinoma.

This study had two purposes: to optimize the semiquantitative interpretation of 18F-fluorodeoxyglucose (FDG) PET scans in the diagnosis of pancreatic carcinoma by analyzing different cutoff levels for the standardized uptake value (SUV), with and without correction for serum glucose level (SUV(gluc)); and to evaluate the usefulness of FDG PET when used in addition to CT for the staging and management of patients with pancreatic cancer. METHODS: Sixty-five patients who presented with suspected pancreatic carcinoma underwent whole-body FDG PET in addition to CT imaging. The PET images were analyzed visually and semiquantitatively using the SUV and SUV(gluc). The final diagnosis was obtained by pathologic (n = 56) or clinical and radiologic follow-up (n = 9). The performance of CT and PET at different cutoff levels of SUV was determined, and the impact of FDG PET in addition to CT on patient management was reviewed retrospectively. RESULTS: Fifty-two patients had proven pancreatic carcinoma, whereas 13 had benign lesions, including chronic pancreatitis (n = 10), benign biliary stricture (n = 1), pancreatic complex cyst (n = 1) and no pancreatic pathology (n = 1). Areas under receiver operating characteristic curves were not significantly different for SUV and SUV(gluc). Using a cutoff level of 3.0 for the SUV, FDG PET had higher sensitivity and specificity than CT in correctly diagnosing pancreatic carcinoma (92% and 85% versus 65% and 61%). There were 2 false-positive PET (chronic pancreatitis, also false-positive with CT) and 4 false-negative PET (all with true-positive CT, abnormal but nondiagnostic) examinations. There were 5 false-positive CT (4 chronic pancreatitis and 1 pancreatic cyst) and 18 false-negative CT (all with true-positive FDG PET scans) examinations. FDG PET clarified indeterminate hepatic lesions or identified additional distant metastases (or both) in 7 patients compared with CT. Overall, FDG PET altered the management of 28 of 65 patients (43%). CONCLUSION: FDG PET is more accurate than CT in the detection of primary tumors and in the clarification and identification of hepatic and distant metastases. The optimal cutoff value of FDG uptake to differentiate benign from malignant pancreatic lesions was 2.0. Correction for serum glucose did not significantly improve the accuracy of FDG PET. Although FDG PET cannot replace CT in defining local tumor extension, the application of FDG PET in addition to CT alters the management in up to 43% of patients with suspected pancreatic cancer.     

High-risk melanoma: accuracy of FDG PET/CT with added CT morphologic information for detection of metastases

PURPOSE: To prospectively determine the accuracy of positron emission tomography (PET)/computed tomography (CT) with added CT morphologic information for depiction of metastases in patients with high-risk melanoma and negative findings for metastases at PET, by using histologic findings or additional imaging and/or follow-up findings as reference standard. MATERIALS AND METHODS: Institutional review board approval was obtained. Informed consent was obtained from patients. One hundred twenty-four consecutive high-risk melanoma patients (65 female, 59 male; mean age, 54.4 years; range, 15-82 years) were included. Fluorine 18 fluorodeoxyglucose (FDG) PET/CT was performed. First, PET/CT scans were evaluated for presence of metastases with increased FDG uptake; CT anatomic location was determined. Lesions were considered metastases if there was focal uptake higher than that of background tissue. Second, coregistered CT images of combined PET/CT scans were evaluated for presence of lesions without FDG uptake. Findings were compared with reference standard findings to determine the accuracy of each evaluation. McNemar test was used to assess statistical differences in accuracy. RESULTS: In 53 of 124 patients, metastases were found. In 46 of 53 patients with metastases, lesions had increased FDG uptake. In seven patients with metastatic disease, metastases did not have increased FDG uptake (maximum standard uptake value [SUV], <1.5; n = 5) or had faint FDG uptake (maximum SUV, 2.5 and 2.9; n = 2)-findings that were inconclusive with PET alone. These lesions were interpreted as metastases only with coregistered CT images. Lesions missed with PET were located in the lungs, iliac lymph nodes, subcutis, and psoas muscle. Sensitivity, specificity, and accuracy, respectively, of PET/CT for depiction of metastases were 85%, 96%, and 91%, and those of PET/CT with dedicated CT interpretation were 98%, 94%, and 96% (P = .016). CONCLUSION: Dedicated analysis of coregistered CT images significantly improves the accuracy of integrated PET/CT for depiction of metastases in patients with high-risk melanoma.     

Splenic fluorodeoxyglucose uptake increased by granulocyte colony-stimulating factor therapy: PET imaging results.

Using PET, we investigated the change in 18F-fluorordeoxyglucose (FDG) uptake in the spleen after granulocyte colony-stimulating factor (G-CSF) treatment. METHODS: Forty-two FDG PET scans in 12 patients with locally advanced breast cancer who received G-CSF treatment were studied (12 baseline, 10 during G-CSF, 20 after G-CSF treatment). The PET images obtained at 50-60 and 60-70 min after intravenous FDG (370 MBq) injection were assessed visually and were compared with those before G-CSF treatment. For a semiquantitative index of FDG uptake, we determined the standardized uptake value calculated on the basis of predicted lean body mass (SUL) on these images, and we calculated the SUL ratios normalized to their baseline SUL values. RESULTS: During G-CSF treatment (n = 10), 9 scans (90%) showed increased splenic FDG uptake (3 slightly, 6 substantially). After G-CSF treatment (n = 20), 13 (65%) showed no change, 7 (35%) showed slightly increased uptake, but no case showed substantially increased FDG uptake in the spleen (P = 0.0003). Out of 30 PET scans obtained during and after G-CSF treatment, 16 (53%) showed increased FDG uptake in the spleen (10 slightly, 6 substantially), whereas 26 (87%) showed increased bone marrow FDG uptake (14 slightly, 12 substantially). The FDG uptake in other normal organs (liver, blood and lung) showed no change during or after G-CSF treatment. Similar to the change in the bone marrow, the SULs in the spleen significantly increased during G-CSF treatment (baseline, 1.50+/-0.31, versus during G-CSF, 2.69+/-0.84; P = 0.0004), then decreased after discontinuation of G-CSF (1.65+/-0.23). There was a significant correlation between the SUL ratios in the spleen and those in the bone marrow (r = 0.778, P < 0.0001), whereas there were no correlations between those in other organs and those in the bone marrow. CONCLUSION: Substantially increased FDG uptake was observed in the spleen during and after G-CSF treatment, although this change was less frequent and not as marked as the change observed in the bone marrow. The recognition and understanding of this phenomenon will be increasingly important when interpreting FDG PET images in cancer patients to avoid confusing this normal phenomenon with pathological splenic (tumor) involvement.     

FDG uptake by the bone marrow in NSCLC patients is related to TGF-β but not to VEGF or G-CSF serum levels

Introduction Non small cell lung carcinomas (NSCLC) are known to secrete various cytokines such as VEGF (vascular endothelial growth factor), G-CSF (granulocyte-colony stimulating factor) and TGF-β (transforming growth factor-beta) that may stimulate bone marrow activity. Purpose This study reports on the relationship between serum levels of VEGF, G-CSF, TGF-β and FDG uptake by the bone marrow in NSCLC patients. Methods Thirty-three patients suffering from newly diagnosed NSCLC who were successively referred to undergo an FDG PET scan as a part of their routine staging procedure and that did not suffer from bone metastases were included in the study. FDG bone marrow activity was determined in all patients and related to pre-treatment VEGF, G-CSF and TGF-β serum levels. Results Mean standardized uptake values (SUV mean) of the bone marrow ranged from 0.1 to 2.1 (mean 1.1). G-CSF, VEGF and TGF-β serum levels ranged from 13.5 to 110 pg/ml (mean 41.4 pg/ml), from 95 to 3,221 pg/ml (mean 1,111 pg/ml) and from 269 to 615 pg/ml (mean 387 pg/ml), respectively. SUV mean values of the bone marrow significantly correlated with TGF-β serum measurements (r = 0.621, p < 0.0001), but not with VEGF and G-CSF measurements. Conclusion FDG uptake by bone marrow in newly diagnosed NSCLC patients correlates with serum levels of TGF-β, but not with VEGF or G-CSF levels.     

La tomografía por emisión de positrones asociada con la tomografía computarizada en tumores del aparato locomotor

Positron emission tomography/computed tomography (PET/CT) is a hybrid imaging technique that combines the anatomic information from CT with the metabolic information acquired from PET after the administration of specific radiotracers, the most commonly used of which is F18-fluorodeoxyglucose (FDG). In oncology, this technique is based on the increased uptake of FDG by malignant lesions. In the locomotor apparatus, some uptake by bones and soft tissues is physiological or benign and this uptake must be differentiated from uptake by malignancies, whether primary or secondary. The most important limitations are active inflammatory or infectious processes, which are positive on PET images, and malignant lesions that are smaller than 1 cm, cystic, necrotic, or low-grade, which are negative on PET images. PET/CT in the locomotor apparatus is especially useful for the detection of metastases from the most common tumors. It is also used for staging and monitoring the response to treatment of some hematological tumors like lymphoma, where it is fundamental to determine whether the bone marrow has been infiltrated, or myeloma. Lastly, although it is not yet an established indication, PET/CT is being increasingly used to study sarcomas, because it can provide additional information that can be useful for the characterization and grading of tumors, for guiding biopsies, for staging and re-staging, and for evaluating the response to neoadjuvant therapy as well as for evaluating new drugs in clinical trials.     

Diagnostic accuracy of FDG PET imaging for the detection of recurrent or metastatic gynecologic cancer

PURPOSE: This study evaluated the diagnostic role and accuracy of positron emission tomography (PET) using 2-[F-18]fluoro-2-deoxy-D-glucose (FDG) for the detection of tumor foci in patients with suspected recurrent or metastatic lesions of gynecologic cancers. MATERIALS AND METHODS: FDG PET imaging was performed on 51 patients with a previous history of gynecologic cancer who were referred for a clinical suspicion of recurrent disease. PET acquisition was started 50-60 min after the intravenous injection of 5-6 MBq/kg FDG in all patients. The PET images were interpreted visually, and tracer uptake was quantitated as the standardized uptake value adjusted to body weight (SUV) in the lesions showing FDG uptake. The accuracy of the PET results was assessed by a consensual verdict based on histology, cytology, other imaging and clinical follow-up. RESULTS: FDG PET correctly diagnosed 33 of 36 patients with recurrent disease and 12 of 15 patients without recurrence. On patient-based analysis, the sensitivity, specificity and accuracy of FDG PET were 91.7%, 80.0% and 88.2%, respectively, depending on the selected scheme for visual scoring of the lesions. The area index in receiver-operating characteristic analysis was 0.95 for patient detection. Malignant lesions accumulated significantly more FDG than the benign ones (the mean SUVs were 3.7 +/- 1.9 and 1.6 +/- 1.1, respectively, p = 0.004). The sensitivity and specificity in correct identification of tumor recurrence or metastases using a threshold SUV 1.9 were 88.8% and 66.7% in contrast to the visual analysis (sensitivity 96.4%, specificity 50%) on a lesion-based analysis. The partial volume effect of SUV in a few small lesions and the presence of bone lesions in which FDG uptake was relatively low might be the reason for the lower sensitivity in SUV analysis. FDG PET was valuable when CT/MRI was negative or inconclusive, and in patients with elevated tumor marker levels as well as with normal tumor marker levels when recurrence was suspected clinically. However, PET failed to visualize some small metastatic lesions in lung and bone, and showed falsely high FDG uptake in some benign lesions. CONCLUSION: The results indicated that FDG PET is a reliable and accurate diagnostic method for detecting recurrent or metastatic gynecologic cancer particularly lymph node metastases. Although the sensitivity of PET for detecting small metastases was relatively limited, the overall sensitivity of FDG PET was significantly higher than morphologic imaging.     

Non-Specific Disease Mimicking Malignancy: Two Cases of FDG Uptake in the Extremities

FDG PET is an imaging technique used to assess regional differences in glucose metabolism. A variety of diseases, including malignancy, can show abnormal FDG uptake in bone marrow. PET/CT demonstrated non-specific uptake in the extremities of two patients with fever of unknown origin (FUO). Both patients showed focal and symmetric FDG uptake in the bone marrow of the arms and legs. Although the results of these cases were not diagnostic, the unique uptake pattern of PET/CT should be considered a non-specific reactive change as well as malignancy or other possibilities in the initial differential diagnosis.     

动态18F-FDG PET定量分析用于骨病变鉴别诊断

目的 评价^18F-脱氧葡萄糖（FDG）PET在骨骼病变中的诊断价值。谅研究对象为40例原发性骨骼病变患者。所有患者在注射示踪剂后立即开始动态PET采集，持续60min。对动态PET图像进行半定量分析，分别计算平均和最大标准摄取值（SUVaver和SUVmax)，病灶SUV／肌肉SUV比值（T／M），病灶60min SUV/30min SUV比值（SUVaver60/30min和SUVmax60/30min）等。采用Patlak作图分析法对动态图像数据进行拟合计算，得出摄入常数（Ki），计算FDG代谢率（MRFDG）。根据接受器工作特性曲线（ROC）确定各定量指标的诊断阈值，并比较其鉴别良恶性病变的灵敏度和特异性。结果 经病理检查证实恶性病变21例，良性病变19例。恶性病变的MRFDG和SUV值高于良性病变，但各种指标的数值分布均存在交叉重叠。SUVaver与MRFDG呈正相关（r=0.67)。以SUV值≥1.8作为阈值时，鉴别良恶性病变的灵敏度和特异性分别为85．0％和82．4％，以MRFDG（1．1）为阈值时的灵敏度（82．4％）与SUV相近，而特异性（92．9％）较高。同时采用SUV（1．8）和SUVaver60/30min(1.1)作为鉴别标准时，较之单独有用SUV特异性可改善为93．3％，灵敏度略有降低（81．3％）。结论 骨骼良恶性病变之间存在葡萄糖代谢率差异。单用静态FDG PET获取SUV值不能很好鉴别骨骼良恶性病变。动态显像定量分析可提供更有价值的信息。根据动态图像进行半定量分析获取可反映动态过程的摄取指标，可能是一种较简便和有价值的鉴别方法。     

A Computed Tomography-Based Spatial Normalization for the Analysis of [18F] Fluorodeoxyglucose Positron Emission Tomography of the Brain

Objective

We developed a new computed tomography (CT)-based spatial normalization method and CT template to demonstrate its usefulness in spatial normalization of positron emission tomography (PET) images with [¹⁸F] fluorodeoxyglucose (FDG) PET studies in healthy controls.

Materials and Methods

Seventy healthy controls underwent brain CT scan (120 KeV, 180 mAs, and 3 mm of thickness) and [¹⁸F] FDG PET scans using a PET/CT scanner. T1-weighted magnetic resonance (MR) images were acquired for all subjects. By averaging skull-stripped and spatially-normalized MR and CT images, we created skull-stripped MR and CT templates for spatial normalization. The skull-stripped MR and CT images were spatially normalized to each structural template. PET images were spatially normalized by applying spatial transformation parameters to normalize skull-stripped MR and CT images. A conventional perfusion PET template was used for PET-based spatial normalization. Regional standardized uptake values (SUV) measured by overlaying the template volume of interest (VOI) were compared to those measured with FreeSurfer-generated VOI (FSVOI).

Results

All three spatial normalization methods underestimated regional SUV values by 0.3-20% compared to those measured with FSVOI. The CT-based method showed slightly greater underestimation bias. Regional SUV values derived from all three spatial normalization methods were correlated significantly (p < 0.0001) with those measured with FSVOI.

Conclusion

CT-based spatial normalization may be an alternative method for structure-based spatial normalization of [¹⁸F] FDG PET when MR imaging is unavailable. Therefore, it is useful for PET/CT studies with various radiotracers whose uptake is expected to be limited to specific brain regions or highly variable within study population.     

Quantitative evaluation of skeletal tumours with dynamic FDG PET: SUV in comparison to Patlak analysis.

This study was carried out to evaluate bone lesions using fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) and to explore whether dynamic and quantitative PET data may help to differentiate benign lesions from malignant masses. Forty patients with primary bone lesions were studied. The final diagnosis was confirmed by histopathology. A 60-min dynamic FDG PET acquisition was undertaken in all subjects. From the dynamic PET images, indices such as the average and maximal standardised uptake values (SUVs), the tumour SUV-to-muscle SUV ratio (T/M) and the SUV at 60 min-to-SUV at 30 min ratio (averSUV60/30 min and maxSUV60/30 min) were produced. Patlak graphical analysis was used to obtain the influx constant (Ki), and the metabolic rate of FDG (MRFDG) was calculated. Based on the receiver operator characteristic curve, the sensitivity and specificity for each parameter in differentiating between malignant and benign lesions were evaluated. The histological results revealed 21 malignant tumours and 19 benign lesions in this group. The MRFDG and SUV indices in malignant lesions were significantly higher than those in benign lesions. However, each index showed a considerable overlap between benign and malignant lesions. Average SUV correlated positively with MRFDG (r=0.67). When a cut-off of 1.8 average SUV was used, the sensitivity and specificity for discrimination of malignancy from benign disease were 85% and 82.4%, respectively. MRFDG showed a similar sensitivity (82.4%) and a better specificity (92.9%). A combination consisting of a cut-off of average SUV (1.8) and averSUV60/30 min (1.1) resulted in an improvement of specificity to 93.3%, with a small reduction in sensitivity (81.3%) as compared with exclusive use of SUV. The results of this study indicate that a detectable difference in glucose metabolism exists between malignant and benign skeletal lesions. The static FDG uptake indices alone may not enable adequate differentiation between benign and malignant lesions. Quantitative dynamic imaging may provide more helpful information, but will not permit a definite diagnosis. The use of uptake indices may represent an alternative and interesting approach to the evaluation of bone lesions.     

Differentiation between malignant and benign pathologic fractures with F-18-fluoro-2-deoxy-<Emphasis Type="SmallCaps">D</Emphasis>-glucose positron emission tomography/computed tomography

Objective To evaluate the efficacy of F-18-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG PET/CT) in differentiating malignant from benign pathologic fractures. Materials and methods F-18 FDG PET/CT was performed on 34 patients with pathologic fractures between May 2004 and June 2007. Fractures were located in tubular bones (26), in the pelvis (six), in the spine (one) and in a rib (one). The FDG uptake pattern at the fracture site was described, whether FDG uptake occurred in the marrow or cortex and soft tissue. Maximum standardized uptake values (SUVmax, the largest value at the region of interest) were measured at the fracture site, including cortical bone, bone marrow and soft tissue. As a reference standard, biopsy was used for 12 patients and clinical follow-up for 22 patients. Sensitivity, specificity and diagnostic accuracy of PET/CT were calculated. Results There were 19 malignant and 15 benign fractures. In the malignant fractures, PET/CT demonstrated high (mean SUVmax 12.0, range 4.3 to 45.7) F-18 FDG uptake in bone marrow in most cases (17 of 19). In benign fractures, there was low FDG uptake (mean SUVmax 2.9, range 0.6 to 5.5) within cortical bone or adjacent soft tissue around the fracture, rarely in the marrow. There were significant differences in the pattern of intramedullary FDG uptake (P < 0.001) and in the mean SUVmax (P < 0.01) between malignant and benign fractures. The sensitivity, specificity and diagnostic accuracy of F-18 FDG PET/CT were 89.5%, 86.7% and 88.2%, respectively, with a cut-off SUVmax set at 4.7. The time interval between fracture and PET/CT did not significantly influence FDG uptake at the fracture site. Conclusion F-18 FDG PET/CT reliably differentiated between malignant and benign fractures based on the SUVmax and based on medullary uptake, which was characteristic for malignant fractures. This research was supported by the Yeungnam University research grants in 2007.     

Diffuse bone marrow uptake on F-18 FDG PET in patients with myelodysplastic syndromes

It is well known that hematopoietic cytokine stimulation can cause diffuse increase of FDG accumulation in bone marrow on PET imaging, which simulates that seen in patients with bone marrow metastases. However, diffuse bone marrow FDG uptake can be caused by other etiologies. We report 2 patients who did not have a history of hematopoietic cytokine stimulation. The FDG PET images showed diffuse bone marrow FDG uptake, and the patients were diagnosed as having myelodysplastic syndromes. These cases demonstrate that diffuse FDG uptake by bone marrow can suggest neoplastic disease of the hematopoietic tissues.     

Estimation of local statistical noise in PET images induced by attenuation inside the body

Objectives  

In positron emission tomography/computed tomography (PET/CT) examinations, the standardized uptake value (SUV) is a commonly used index to evaluate the activity of cancer. The precision of SUV is directly affected by the local statistical noise in PET images because SUV is calculated based on the counts on PET image data. The purpose of this study was to estimate the local statistical noise in the PET image caused by attenuation of annihilation photons inside the body.     

Comparison of imaging with FDG PET/CT with other imaging modalities in myeloma

Objective To determine the usefulness of FDG PET/CT scanning in the management and staging of myeloma and to assess its strengths and limitations.Design FDG PET/CT scans and all other available imaging studies were reviewed retrospectively from 16 consecutive patients by two experienced musculoskeletal radiologists and two nuclear medicine physicians working in consensus.Patients The 16 patients had undergone a total of 19 FDG PET/CT scans. Radiographs were available in all cases, including 13 skeletal surveys; 25 CT scans (16 chest, three abdominal, four pelvic, one spine, one neck) and 22 MR imaging studies (17 spine, three pelvic, two extremity) also were reviewed. Patients’ records were examined for relevant clinical information. All focal areas of abnormal FDG uptake were correlated with the other imaging studies to determine clinical significance. FDG PET/CT scans also were reviewed to see if small lesions shown on the other imaging studies could be identified in retrospect.Results The 12 men and four women had an average age of 58 years (range 30–69 years). All 16 patients had an established diagnosis of multiple myeloma, with average duration of disease, from time of initial diagnosis to review, of 30 months (range 6 months to 11+ years). The FDG PET/CT scans revealed a total of 104 sites (90 in bone, 14 soft tissue) that were suspicious for neoplastic activity based on a standardized uptake value (SUV) greater than 2.5. Fifty-seven of these sites (55%) were new or previously undetected. The other imaging studies (X-ray, CT, MR) and clinical information confirmed the other 47 areas but also revealed 133 other small skeletal lesions. Six of these 133 additional lesions showed mild FDG uptake on re-review of the PET/CT scans. The FDG PET/CT findings led to management changes in 9/16 patients. MR imaging revealed five cases of diffuse bone involvement (four spine, one scapula) that were not evident by FDG PET/CT.Conclusion FDG PET/CT scans are useful for the management and staging of myeloma. However, if PET/CT were the sole imaging study done, it would miss many additional small lytic skeletal lesions and could miss diffuse spine involvement.     

PET/CT对胃腺癌的诊断价值与胃镜对比分析

目的:评价PET/CT对胃腺癌(GA)的诊断价值.方法:回顾性分析经病理证实的15例GA资料,所有病例均行PET/CT检查,14例行胃镜检查并与胃镜结果比较.结果:PET/CT显示原发肿瘤氟脱氧葡萄糖(FDG)摄取增高14例,敏感性为93％0,标准摄取值(SUV)最大值5.92±3.11,SUV平均值3.17±0.89,同时在11例患者中发现FDG摄取增高转移灶41处,SUV最大值5.03±2.74,SUV平均值2.76±1.01.胃镜结合活体组织取材进行病理学检查诊断符合率100％.结论:对于有胃镜检查禁忌症的患者,以及需要进一步临床分期的GA患者,PET/CT是一种有效的检查方法.