Evaluation of a new motion correction algorithm in PET/CT: combining the entire acquired PET data to create a single three-dimensional motion-corrected PET/CT image.

PURPOSE: This study evaluated the potential of Q.Freeze algorithm for reducing motion artifacts, in comparison with ungated imaging (UG) and respiratory-gated imaging (RG). PATIENTS AND METHODS: Twenty-nine patients with 53 lesions who had undergone RG F-FDG PET/CT were included in this study. Using PET list mode data, five series of PET images [UG, RG, and QF images with an acquisition duration of 3 min (QF3), 5 min (QF5), and 10 min (QF10)] were reconstructed retrospectively. The image quality was evaluated first. Next, quantitative metrics [maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), SD, metabolic tumor volume, signal to noise ratio, or lesion to background ratio] were calculated for the liver, background, and each lesion, and the results were compared across the series. RESULTS: QF10 and QF5 showed better image quality compared with all other images. SUVmax in the liver, background, and lesions was lower with QF10 and QF5 than with the others, but there were no statistically significant differences in SUVmean and the lesion to background ratios. The SD with UG and RG was significantly higher than that with QF5 and QF10. The metabolic tumor volume in QF3 and QF5 was significantly lower than that in UG. CONCLUSION: The Q.Freeze algorithm can improve the quality of PET imaging compared with RG and UG.

Comparison of (11)C-4'-thiothymidine, (11)C-methionine, and (18)F-FDG PET/CT for the detection of active lesions of multiple myeloma.

PURPOSE: The aims of this study were to evaluate the possibility of using (11)C-methionine ((11)C-MET) and (11)C-4'-thiothymidine ((11)C-4DST) whole-body PET/CT for the imaging of amino acid metabolism and DNA synthesis, respectively, when searching for bone marrow involvement in patients with multiple myeloma (MM) and to compare these findings with those for (18)F-FDG PET/CT and aspiration cytology. METHODS: A total of 64 patients with MM, solitary plasmacytoma, monoclonal gammopathy of undetermined significance, or an unspecified diagnosis were prospectively enrolled. All the patients underwent three whole-body PET/CT examinations within a period of 1 week. First, the tracer accumulation was visually evaluated as positive, equivocal, or negative for 55 focal lytic lesions visualized using CT in 24 patients. Second, the percentages of marrow plasma cells as calculated using a bone marrow aspiration smear and tracer accumulation were evaluated in the posterior iliac crests of 36 patients. RESULTS: Among the 55 lytic lesions, the (11)C-MET and (11)C-4DST findings tended to reveal more positive findings than the (18)F-FDG findings. Based on the standard criteria for the diagnosis of active myeloma using the percentage of marrow plasma cells, significant differences were found between the (18)F-FDG and (11)C-MET findings and between the (18)F-FDG and (11)C-4DST findings, but no significant difference was observed between the (11)C-MET and (11)C-4DST findings. CONCLUSION: The addition of (11)C-MET and (11)C-4DST to (18)F-FDG when performing PET/CT enabled clearer evaluations of equivocal lesions. Based on cytological diagnostic criteria, (11)C-MET and (11)C-4DST were more sensitive than (18)F-FDG for the detection of active lesions. (11)C-MET and (11)C-4DST were more useful than (18)F-FDG for the detection of active lesions, especially during the early stage of disease.

Volumetric comparison of positron emission tomography/computed tomography using 4'-[methyl-¹¹C]-thiothymidine with 2-deoxy-2-¹8F-fluoro-D-glucose in patients with advanced head and neck squamous cell carcinoma.

OBJECTIVE: We prospectively compared the diagnostic value of PET/computed tomography (CT) findings using the tracers 4'-[methyl-11C]-thiothymidine (11C-4DST) and 2-deoxy-2-18F-fluoro-D-glucose (18F-FDG) in patients with head and neck squamous cell carcinoma (HNSCC). PATIENTS AND METHODS: Thirty-eight patients with advanced HNSCC underwent 11C-4DST PET/CT and 18F-FDG PET/CT before treatment. Maximum standardized uptake values (SUVmax) were measured for both PET/CT studies; in addition, total lesion glycolysis (TLG) of 18F-FDG PET/CT and total lesion proliferation (TLP) of 11C-4DST PET/CT were measured. Absolute TLG and TLP values as well as values with various SUV thresholds were measured. All patients were followed up for 13.5±7.5 months (mean±SD) to monitor recurrence. RESULTS: A statistically significant correlation was observed between the primary tumor SUVmax for 11C-4DST PET/CT and 18F-FDG PET/CT (r=0.46, P<0.01). TLP values with SUV thresholds strongly correlated with TLG values relative to the same thresholds (r=0.60-0.92, P<0.001). Nine of the 38 patients with post-treatment recurrence were identified. Receiver operating characteristic curves for TLG3.0 and TLP2.5 showed the highest prognostic ability for recurrence; the sensitivity and specificity of TLG3.0 were 89 and 72%, respectively, and the sensitivity and specificity of TLP2.5 were 89 and 55%, respectively. CONCLUSION: In patients with advanced HNSCC, the TLP of 11C-4DST PET/CT strongly correlated with the TLG of 18F-FDG PET/CT. Although there were no large differences between these values, the receiver operating characteristic curves of the absolute TLG had slightly better prognostic ability for recurrence.

Differences in fluorodeoxyglucose positron emission tomography/computed tomography findings between elderly onset rheumatoid arthritis and polymyalgia rheumatica.

OBJECTIVES: To compare the fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) findings in patients with elderly-onset rheumatoid arthritis (EORA) with those in patients with polymyalgia rheumatica (PMR), two conditions with similar clinical presentations. METHODS: We retrospectively analyzed the FDG-PET/CT findings in 10 patients with EORA and 27 patients with PMR admitted to our department between 2006 and 2012. RESULTS: No significant difference was observed in the median patient ages at the time of FDG-PET/CT scans in the EORA and PMR groups (73.5 vs. 78.0 years, respectively). Significant differences in both FDG uptake scores and standardized uptake values were observed between the two groups in the ischial tuberosities, spinous processes, and wrists. No significant differences were detected in the shoulders and hips. However, specific uptake patterns were observed in each group: circular and linear uptake patterns were observed around the humeral head in the EORA group, whereas focal and non-linear uptake patterns were observed in the PMR group. Moreover, focal uptake in front of the hip joint, indicating iliopectineal bursitis, tended to be limited to the PMR group. High sensitivity (92.6%) and specificity (90%) were observed for PMR diagnoses when at least three of the following five items were satisfied: characteristic findings of shoulder and iliopectineal bursitis, FDG uptake in ischial tuberosities and spinal spinous processes, and lack of FDG uptake in the wrists. CONCLUSION: The differences in the degree of uptake at each lesion and in uptake patterns at the shoulders and hips are potentially useful for obtaining a definitive diagnosis.

Lesion-based analysis of (18)F-FDG uptake and (111)In-Pentetreotide uptake by neuroendocrine tumors.

PURPOSE: To characterize the heterogeneity of metastatic neuroendocrine tumor (NET) lesions, we compared the [(18)F]-fluorodeoxyglucose (FDG) uptake and the (111)In-pentetreotide (SRS) uptake for somatostatin receptor scintigraphy using the CT-based fusion imaging techniques of PET/CT and SPECT/CT. METHODS: Fifteen consecutive patients with NET lesions were examined using both FDG-PET/CT and SRS SPECT/CT prospectively. A total of 45 metastatic NET lesions were evaluated for FDG uptake according to the standardized uptake value (SUV) and for SRS uptake according to the tumor-to-muscle count ratio (T/M ratio); these values were then compared according to the grade of NET (G), also compared to the tumor volume. RESULTS: Both the SRS uptake and FDG uptake showed no significant correlation to the tumor volume, and suggested no significant artifacts in these data. The T/M ratio for the SRS uptake ranged from 192.7 to 1.9 and exhibited very wide range of distribution. The SUV for the FDG uptake ranged from 13.8 to 0.77 and exhibited narrow range of distribution. The uptake of the two tracers in individual lesions showed an inverse correlation. The G1 + 2 lesions had a higher SRS uptake than the G3 lesions, but the difference was not significant because of the large variation (40.65 ± 48.03, n = 39 vs. 8.66 ± 13.13, n = 6). However, the G1 + 2 lesions had a significantly lower FDG uptake than the G3 lesions (3.52 ± 1.84, n = 39 vs. 10.82 ± 4.50, n = 6). The tracer uptakes varied largely not only in an inter-subject manner, but also in an intra-subject manner. CONCLUSION: An inverse correlation between SRS uptake and FDG uptake in the metastatic NET lesions observed in this study may be consistent with the opposing ideas of differentiation and proliferation in oncology. The large variations in SRS and FDG uptake by metastatic NET lesions suggest the biological heterogeneity of advanced NET. These results support the idea that combination therapy targeting both receptor-positive cells and proliferating cells may be beneficial from a functional imaging perspective.

Utility of fluorodeoxyglucose positron emission tomography/computed tomography for early diagnosis and evaluation of disease activity of relapsing polychondritis: a case series and literature review.

OBJECTIVE: Relapsing polychondritis (RPC) is relatively rare and early diagnosis is difficult. We investigated the utility of fluorodeoxyglucose (FDG)-PET/CT for the diagnosis of RPC and evaluation of disease activity. METHODS: Five RPC patients undergoing FDG-PET/CT in our hospital between 2006 and 2012 were studied. Eight RPC cases examined by PET reported in the literature were also assessed. Data from a total of 13 patients were analysed. RESULTS: Typical FDG accumulation was noted in the tracheobronchial trees of nine patients, the costal cartilage of five, joints of five, larynx of four, nasal cavity/paranasal sinuses of three, auricles of three, lymph nodes of three and the aorta of one. One patient showed nasal chondritis on a PET scan despite the absence of nasal changes on physical examination. Of five patients with costochondritis, four remained asymptomatic. Of nine patients with airway FDG accumulation, eight developed respiratory symptoms and all had CT abnormalities. In the other patient, airway FDG accumulation was evident despite the absence of airway symptoms and a lack of abnormalities in the respiratory function test and CT. PET also revealed bronchial chondritis in asymptomatic patients. The mean maximum standardized uptake values (SUVmax) of the upper and lower airways was 5.79 (s.d. 2.87) and 6.47 (s.d. 4.08), respectively. In five patients with a PET after treatment, FDG accumulation had diminished with symptomatic and inflammatory improvement. CONCLUSION: FDG-PET/CT is a potentially powerful tool for the early diagnosis of RPC, especially in patients without easily biopsied organ involvement. This modality also facilitates evaluation of disease extent and disease activity during treatment.

A pilot study of 4'-[methyl-11C]-thiothymidine PET/CT for detection of regional lymph node metastasis in non-small cell lung cancer.

BACKGROUND: 4'-[methyl-11C]-thiothymidine (4DST) is a novel positron emission tomography (PET) tracer to assess proliferation of malignancy. The diagnostic abilities of 4DST and 2-deoxy-2-18 F-fluoro-d-glucose (FDG) for detecting regional lymph node (LN) metastases of non-small cell lung cancer (NSCLC) were prospectively compared. In addition, the relationship between the PET result and the patient's prognosis was evaluated. METHODS: A total of 31 patients with NSCLC underwent 4DST PET/computed tomography (CT) and FDG PET/CT. The PET/CT images were evaluated qualitatively and quantitatively for focal uptake of each PET tracer, according to the staging system of the American Joint Committee on Cancer. Surgical and histological results provided the reference standards. Patients were followed for up to two years to assess disease-free survival. RESULTS: On a per-lesion basis, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for LN staging were 82%, 72%, 32%, 96%, and 73%, respectively, for 4DST, and 29%, 86%, 25%, 88%, and 78%, respectively, for FDG. The sensitivity of 4DST was significantly higher than that of FDG (P < 0.001). The disease-free survival rate with positive 4DST uptake in nodal lesions was 0.35, which was considerably lower than the rate of 0.83 with negative findings (P = 0.04). Among the factors tested, nodal staging by 4DST was the most influential prognostic factor (P = 0.05) in predicting the presence of a previously existing spread lesion or of a recurrence over the course of 2 years. CONCLUSION: 4DST PET/CT is sensitive for detecting mediastinal lymph node metastasis in NSCLC, but its low specificity is a limitation. However, it may be helpful in predicting the prognosis of NSCLC.

Prognostic value of post-treatment (18)F-FDG PET/CT for advanced head and neck cancer after combined intra-arterial chemotherapy and radiotherapy.

OBJECTIVE: To clarify the prognostic value of post-treatment (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in patients with advanced head and neck squamous cell carcinoma (HNSCC) after combined intra-arterial chemotherapy and radiotherapy (IACR). METHODS: Thirty-six patients with HNSCC who underwent IACR were recruited. The period from the end of IACR to the last post-treatment (18)F-FDG PET/CT examination was 8-12 weeks. Both patient-based and lesion-based analyses were used to evaluate the PET/CT images. For lesion-based analysis, 36 regions (12 lesions of recurrences and 24 scars at primary sites) were selected. The Kaplan-Meier method was used to assess the overall survival (OS) stratified by (18)F-FDG uptake or visual interpretation results. RESULTS: Twelve patients with recurrence were identified by six months after IACR. The sensitivity and specificity in the patient-based analysis were 67% (8/12) and 88% (21/24), respectively. The mean OS was estimated to be 12.1 months (95% CI, 6.3-18.0 months) for the higher maximum standardized uptake value (SUVmax) group (n=7) and 44.6 months (95% CI, 39.9-49.3 months) for the lower SUVmax group (n=29). OS in the higher SUVmax group (cut-off point, 6.1) or positive visual interpretation group was significantly shorter than that in the lower SUVmax or negative visual interpretation group (P<0.001 and P<0.05, respectively). CONCLUSIONS: The SUVmax and visual interpretation of HNSCC on post-IACR (18)F-FDG PET/CT can provide prognostic survival estimates.

Long fasting is effective in inhibiting physiological myocardial 18F-FDG uptake and for evaluating active lesions of cardiac sarcoidosis.

BACKGROUND: F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is a promising modality for detecting active lesions of cardiac sarcoidosis (CS). However, determining whether 18F-FDG uptake in the myocardium is physiological is challenging due to metabolic shift in myocardial cells. Although methods for inhibiting physiological myocardial 18F-FDG uptake have been proposed, no standard methods exist. This study therefore aimed to compare the effect of an 18-h fast (long fasting (LF)) with heparin loading plus a 12-h fast (HEP) before 18F-FDG PET scan. METHODS: We analyzed the effects of LF and HEP on the inhibition of physiological myocardial 18F-FDG uptake in healthy subjects (18 in HEP and 19 in LF) and in patients with known or suspected CS (96 in HEP and 69 in LF). In CS, the lower uptake of 18F-FDG in the myocardium was evaluated. A visual four-point scale was used to assess myocardial 18F-FDG uptake in comparison with hepatic uptake (1 lower, 2 similar, 3 somewhat higher, 4 noticeably higher). RESULTS: Myocardial 18F-FDG uptake was 1.68 ± 1.06 in LF and 3.17 ± 1.16 in HEP in healthy subjects (p < 0.0001), whereas it was 1.48 ± 0.99 in LF and 2.48 ± 1.33 in HEP in CS patients (p < 0.0001). Logistic regression and regression trees revealed the LF was the most effective in inhibiting myocardial 18F-FDG uptake. In addition, serum free fatty acid levels on intravenous 18F-FDG injection were a possible biomarker. CONCLUSIONS: LF is effective in inhibiting myocardial 18F-FDG uptake, and consequently, it could be useful for evaluating active lesions of CS in 18F-FDG PET images.

18F-FDG PET/CT findings preceded elevation of serum proteinase 3 antineutrophil cytoplasmic antibodies in Wegener granulomatosis.

A 67-year-old woman underwent F-FDG PET/CT after developing a fever of unknown origin. PET/CT revealed intensive FDG uptake at the nasal and lung lesions. On the laboratory data, serum myeloperoxidase antineutrophil cytoplasmic antibodies (ANCA) titer was elevated, although serum directed against proteinase 3 (PR3) ANCA titer was within normal limits. One month after treatment, follow-up PET/CT revealed decreased FDG uptake at the lesions. One year later, serum PR3-ANCA titer elevated, which finally led to a diagnosis of Wegener granulomatosis (WG). WG lesions may be detected earlier by FDG PET/CT than by serum PR3-ANCA titers.

Re-evaluating the potentials and limitations of (99m)Tc-aprotinin scintigraphy for amyloid imaging.

The definitive diagnosis of amyloidosis is made histologically with Congo red stain. Noninvasive imaging techniques for amyloidosis are beneficial for early and definite diagnosis of amyloid deposition in the body. (99m)Tc-aprotinin has the benefit of detecting amyloid deposits mainly in the heart, but it can also detect a wide range of lesions in other locations. The usefulness and limitations of (99m)Tc-Aprotinin scintigraphy for amyloid imaging were re-evaluated based on results from 25 patients (15 men and 10 women; median age, 62.9 y; range, 34-83 y). In addition, other nuclear tracers for imaging amyloidosis are discussed. Of the 25 patients with suspected amyloidosis, 19 patients were proven to have amyloid deposits by histopathological diagnosis. Major (99m)Tc-aprotinin positive sites were confirmed in the myocardium, thyroid, large joints, vertebrae, colon, and lungs. If (99m)Tc-Aprotinin images showed positive findings, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of existing amyloid deposits were 94.7, 33.3, 81.8, and 66.7%, respectively. For analysis based on biopsy region, the sensitivity, specificity, PPV, and NPV of existing amyloid deposition were 30.6, 82.6, 73.3, and 43.2%, respectively. (99m)Tc-Aprotinin has a high potential for diagnosis of amyloid deposition in body; however, due to its physiological uptake, its potential is limited for detection of amyloid deposits in the liver, kidney, and spleen.

Imaging spectrum and pitfalls of ¹8F-fluorodeoxyglucose positron emission tomography/computed tomography in patients with tuberculosis.

Mycobacterium tuberculosis (TB) is one of the most prominant diseases frequently causing false positive lesions in oncologic surveys using (18)F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT), since TB granulomas are composed of activated macrophages and lymphocytes with high affinity for glucose. These pitfalls of (18)F-FDG PET/CT are important for radiologists. Being familiar with (18)F-FDG images of TB could assist in preventing unfavorable clinical results based on misdiagnoses. In addition, (18)F-FDG PET/CT has the advantage of being able to screen the whole body, and can clearly detect harboring TB lesions as high uptake foci. This article details the spectrum and pitfalls of (18)F-FDG PET/CT imaging in TB.

Incidental focal FDG uptake in heart is a lighthouse for considering cardiac screening.

OBJECTIVES: Cardiac FDG uptake is known to show a variety of patterns under clinical fasting conditions. We hypothesized that focal FDG uptake in the heart (FUH) represents a sign of cardiac disease risk, especially in coronary artery disease (CAD).The aim of this study was to clarify the relationship between FUH and cardiac disease. METHODS: Cases showing FUH were selected based on comments in diagnostic reports or identification on retrospective review. Quantitative analysis was performed using maximum standardized uptake value (SUVmax), with regions of interest drawn over focal uptake areas in the heart as confirmed by PET/CT and in lateral side of the same slice showing focal FDG uptake. RESULTS: For the 20 patients (11 men, 9 women) with confirmed FUH, coronary artery stenosis or history of treatment for coronary disease was present in 11 patients (55.0 %), and 2 patients showed apical hypertrophy. Mean SUVmax of FUH did not differ significantly between patients with confirmed cardiac disease and those with no evidence of cardiac disease (P = 0.78). CONCLUSIONS: FUH suggests a high likelihood of CAD in patients without myocardial symptoms. Cardiac screening or a check of the history of cardiac disease is thus worth considering when FUH is seen incidentally on FDG-PET/CT.

Evaluation of Wegener's granulomatosis using 18F-fluorodeoxyglucose positron emission tomography/computed tomography.

OBJECTIVE: Wegener's granulomatosis (WG) is a relatively rare disease characterized by granulomatous necrotizing vasculitis that primarily involves small- and medium-sized vessels. Systemic findings observed on (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) have not been well reported. The purpose of this study was to evaluate the FDG PET/CT imaging in the diagnosis and follow-up of patients with WG. MATERIALS AND METHODS: Thirteen FDG PET/CT images obtained for 8 patients (2 men and 6 women) with WG were retrospectively analyzed. Of these, 6 were performed for diagnosis, 2 for restaging and follow-up, and 5 for assessment of treatment efficacy. Maximum standardized uptake values (max SUVs) and visual analyses were used to interpret the FDG PET/CT images. In addition, nonenhanced CT findings obtained during FDG PET/CT were described. RESULTS: WG lesions of the upper respiratory tract and lung were more clearly detected by FDG PET/CT fusion imaging than by nonenhanced CT alone, and all of the active lesions showed decreased FDG uptake after treatment. In addition, FDG PET/CT can provide complementary information to indicate biopsy site based on FDG uptakes. CONCLUSIONS: FDG PET/CT is a feasible modality for evaluating lesion activities, therapeutic monitoring, and follow-up of WG. Furthermore, biopsy sites of WG lesions may be determined by FDG PET/CT.

Amyloid imaging mismatch.

An 82-year-old man with suspected systemic amyloidosis and complete atrioventricular block underwent vascular biopsy during his pacemaker implantation with pathology showing amyloid deposits. 99mTc-aprotinin SPECT revealed increased radiotracer uptake along the left ventricular wall, consistent with cardiac amyloidosis. 11C-PiB PET/CT performed for the evaluation of amyloid deposits in the brain showed findings suggestive of Alzheimer disease without abnormal radiotracer concentration in the myocardium to match the 99mTc-aprotinin SPECT findings. Dynamic PET images showed increased 11C-PiB concentration in the left ventricular myocardium at 2 minutes after injection, with subsequent tracer clearance by approximately 5 minutes, consistent with normal 11C-PiB biodistribution.

Reevaluation of FDG-PET/CT in patients with hoarseness caused by vocal cord palsy.

OBJECTIVE: Vocal cord palsy (VCP) is a potential cause of hoarseness that results in decreasing mobility of the vocal cord. VCP can arise from a variety of causes; so, systematic screening is warranted for the management of patients with VCP. Asymmetrical fluorodeoxyglucose (FDG) uptake in vocal cords is a well-known feature in patients with VCP, but no detailed analysis has been performed. This study aimed at reevaluating the (18)F-FDG positron emission tomography/computed tomography (PET/CT) for patients with VCP. METHODS: We retrospectively surveyed the results of FDG-PET/CT for 59 patients with VCP, compared to laryngoscopic findings. Quantitative analysis was performed using maximum standardized uptake value (SUVmax), and regions of interest were drawn over bilateral vocal cords as confirmed from the CT portion of PET/CT. Patients were divided into 3 groups: Group 1 (n = 14), in which VCP was caused by the lesion of the laryngeal area; Group 2 (n = 40), in which VCP was caused by the lesion on the root of the recurrent laryngeal nerve; and Group 3 (n = 5), in which VCP was caused by the lesion from the vagal center to the proximal vagus nerve. RESULTS: For Group 1, higher FDG uptake in the paralyzed vocal cord was seen in 86 % of patients (mean SUVmax 8.1 ± 5.3 vs. 2.3 ± 0.4, paralyzed vs. non-paralyzed, respectively; P < 0.002). The sensitivity of FDG-PET/CT for indicating the lesion causing VCP was 79 % for Group 1. Group 2 showed dominant FDG uptake in the non-paralyzed vocal cord (mean SUVmax 2.1 ± 0.9 vs. 1.5 ± 0.4, non-paralyzed vs. paralyzed, respectively; P < 0.001). The sensitivity of FDG-PET/CT for indicating the lesion causing VCP was 93 % for Group 2. Group 3 showed no statistically significant difference in FDG accumulation between non-paralyzed and paralyzed vocal cords (mean SUVmax 1.8 ± 0.3 vs. 1.7 ± 0.3, non- paralyzed vs. paralyzed, respectively; P = 0.30). The sensitivity of FDG-PET/CT for indicating the lesion causing VCP was 60 % for Group 3. CONCLUSIONS: FDG accumulation in the vocal cords is dependent on the lesion site causing VCP. In addition, FDG-PET/CT can contribute to identification of the lesion responsible for inducing VCP.

4'-[Methyl-11C]-thiothymidine PET/CT for proliferation imaging in non-small cell lung cancer.

UNLABELLED: A new tracer, 4'-[methyl-(11)C]-thiothymidine ((11)C-4DST), has been developed as an in vivo cell proliferation marker based on the DNA incorporation method. This study evaluated the potential of (11)C-4DST PET/CT for imaging proliferation in non-small cell lung cancer (NSCLC), compared with (18)F-FDG PET/CT. METHODS: Eighteen patients with lung lesions were examined by PET/CT using (11)C-4DST and (18)F-FDG. We constructed decay-corrected time-activity curves of 9 major regions as the mean standardized uptake value. We then compared the maximum standardized uptake value (SUVmax) of lung tumors on both (11)C-4DST and (18)F-FDG PET/CT with the Ki-67 index of cellular proliferation and with CD31-positive vessels as a marker of angiogenesis in surgical pathology. RESULTS: NSCLC was pathologically confirmed in 19 lesions of 18 patients. Physiologic accumulation of (11)C-4DST was high in liver, kidney, and bone marrow and low in aorta, brain, lung, and myocardium. Biodistribution of (11)C-4DST was almost stable by 20 min after injection of (11)C-4DST. Mean (11)C-4DST SUVmax for lung cancer was 2.9 ± 1.0 (range, 1.5-4.7), significantly different from mean (18)F-FDG SUVmax, which was 6.2 ± 4.5 (range, 0.9-17.3; P < 0.001). The correlation coefficient between SUVmax and Ki-67 index was higher with (11)C-4DST (r = 0.82) than with (18)F-FDG (r = 0.71). The correlation coefficient between SUVmax and CD31 was low with both (11)C-4DST (r = 0.21) and (18)F-FDG (r = 0.21), showing no significant difference between the tracers. CONCLUSION: A higher correlation with proliferation of lung tumors was seen for (11)C-4DST than for (18)F-FDG. (11)C-4DST PET/CT may allow noninvasive imaging of DNA synthesis in NSCLC.