Comparisons between glucose analogue 2-deoxy-2-(18F)fluoro-D-glucose and 18F-sodium fluoride positron emission tomography/computed tomography in breast cancer patients with bone lesions

AIM: To compare 2-deoxy-2-(¹⁸F)fluoro-D-glucose(¹⁸F-FDG) and ¹⁸F-sodium (¹⁸F-NaF) positron emission tomography/computed tomography (PET/CT) accuracy in breast cancer patients with clinically/radiologically suspected or known bone metastases.METHODS: A total of 45 consecutive patients with breast cancer and the presence or clinical/biochemical or radiological suspicion of bone metastatic disease underwent ¹⁸F-FDG and ¹⁸F-fluoride PET/CT. Imaging results were compared with histopathology when available, or clinical and radiological follow-up of at least 1 year. For each technique we calculated: Sensitivity (Se), specificity (Sp), overall accuracy, positive and negative predictive values, error rate, and Youden’s index. McNemar’s χ² test was used to test the difference in sensitivity and specificity between the two diagnostic methods. All analyses were computed on a patient basis, and then on a lesion basis, with consideration ofthe density of independent lesions on the co-registered CT (sclerotic, lytic, mixed, no-lesions) and the divergent site of disease (skull, spine, ribs, extremities, pelvis). The impact of adding ¹⁸F-NaF PET/CT to the work-up of patients was also measured in terms of change in their management due to ¹⁸F-NaF PET/CT findings.RESULTS: The two imaging methods of ¹⁸F-FDG and ¹⁸F-fluoride PET/CT were significantly different at the patient-based analysis: Accuracy was 86.7% and 84.4%, respectively (McNemar’s χ² = 6.23, df = 1, P = 0.01). Overall, 244 bone lesions were detected in our analysis. The overall accuracy of the two methods was significantly different at lesion-based analysis (McNemar’s χ² = 93.4, df = 1, P < 0.0001). In the lesion density-based and site-based analysis, ¹⁸F-FDG PET/CT provided more accurate results in the detection of CT-negative metastasis (P < 0.002) and vertebral localizations (P < 0.002); ¹⁸F-NaF PET/CT was more accurate in detecting sclerotic (P < 0.005) and rib lesions (P < 0.04). ¹⁸F-NaF PET/CT led to a change of management in 3 of the 45 patients (6.6%) by revealing findings that were not detected at ¹⁸F-FDG PET/CT.CONCLUSION: ¹⁸F-FDG PET/CT is a reliable imaging tool in the detection of bone metastasis in most cases, with a diagnostic accuracy that is slightly, but significantly, superior to that of ¹⁸F-NaF PET/CT in the general population of breast cancer patients. However, the extremely high sensitivity of ¹⁸F-fluoride PET/CT can exploit its diagnostic potential in specific clinical settings (i.e., small CT-evident sclerotic lesions, high clinical suspicious of relapse, and negative ¹⁸F-FDG PET and conventional imaging).     

Comparison of 18F-NaF PET/CT with Other Imaging Methods in the Detection of Bone Metastases in Patients with Medullary Thyroid Cancer: a Report of a Series of 31 Cases

PurposeTo compare the ¹⁸F-NaF PET/CT studies (¹⁸F-NaF) with other imaging methods in the detection of skeletal metastases (SM) in patients with medullary thyroid cancer (MTC).MethodsWe retrospectively analyzed 31 patients with MTC who performed ¹⁸F-NaF to assess SM. The results of the ¹⁸F-NaF were compared with other imaging methods performed for metastasis detection: ⁹⁹Tc-MDP bone scan (BS), magnetic resonance imaging (MRI), contrast-enhanced CT (CT), and ⁶⁸Ga-Dotatate and ¹⁸F-FDG PET/CT studies. A qualitative analysis comparing the ¹⁸F-NaF findings with the ones of the other methods was performed, and the results were classified as superior (>), equal (=), and inferior (<).ResultsEleven patients had no bone metastases detected on any of the imaging methods used. Twenty patients presented SM depicted on ¹⁸F-NaF. Of these 20 patients, 12 performed bone scan (in 9 ¹⁸F-NaF > BS and in 3 ¹⁸F-NaF = BS), 1 performed ¹⁸F-FDG (¹⁸F-NaF > ¹⁸F-FDG), 4 performed ⁶⁸Ga-Dotatate (in 2 ¹⁸F-NaF > ⁶⁸Ga-Dotatate and in 2 ¹⁸F-NaF = ⁶⁸Ga-Dotatate), 20 performed CT of at least one body segment (in 15 ¹⁸F-NaF = CT and in 5 ¹⁸F-NaF > CT), and 16 performed MRI of at least one body segment, and in all of them, the ¹⁸F-NaF was equal to the MRI. Beside this, the ¹⁸F-NaF detected SM in body segments not routinely scanned in MRI and CT.ConclusionIn patients with MTC, the ¹⁸F-NaF seems to be equal or superior to other imaging modalities in the detection of SM and allows the analysis of the whole skeletal in a single study.     

Comparison of Diagnostic Sensitivity and Quantitative Indices Between 68Ga-DOTATOC PET/CT and 111In-Pentetreotide SPECT/CT in Neuroendocrine Tumors: a Preliminary Report

Purpose

In-pentetreotide has been used for neuroendocrine tumors expressing somatostatin receptors. Recently, ⁶⁸Ga-DOTATOC PET has been used with the advantage of high image quality. In this study, we compared quantitative indices between ¹¹¹In-pentetreotide SPECT/CT and ⁶⁸Ga-DOTATOC PET/CT.

Methods

Thirteen patients diagnosed with neuroendocrine tumors were prospectively recruited. Patients underwent ¹¹¹In-pentetreotide scans with SPECT/CT and ⁶⁸Ga-DOTATOC PET/CT before treatment. The number and location of lesions were analyzed on both imaging techniques to compare lesion detectability. Additionally, the maximal uptake count of each lesion and mean uptake count of the lungs were measured on both imagings, and target-to-normal lung ratios (TNR) were calculated as quantitative indices.

Results

Among 13 patients, 10 exhibited lesions with increased uptake on ¹¹¹In-pentetreotide SPECT/CT and/or ⁶⁸Ga-DOTATOC PET/CT. Scans with SPECT/CT detected 19 lesions, all of which were also detected on PET/CT. Moreover, 16 additional lesions were detected on PET/CT (6 in the liver, 9 in the pancreas and 1 in the spleen). PET/CT exhibited a significantly higher sensitivity than SPECT/CT (100 % vs. 54 %, P < 0.001). TNR was significantly higher on PET/CT than on SPECT/CT (99.9 ± 84.3 vs. 71.1 ± 114.9, P < 0.001) in spite of a significant correlation (r = 0.692, P = 0.01).

Conclusion

Ga-DOTATOC PET/CT has a higher diagnostic sensitivity than ¹¹¹In-pentetreotide scans with SPECT/CT. The TNR on PET/CT is higher than that of SPECT/CT, which also suggests the higher sensitivity of PET/CT. ¹¹¹In-pentetreotide SPECT/CT should be used carefully if it is used instead of ⁶⁸Ga-DOTATOC PET/CT.     

Prognostic Significance of Volume-based Metabolic Parameters by 18F-FDG PET/CT in Gallbladder Carcinoma

Purpose

We investigated the prognostic values of volume-based metabolic parameters by ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) in gallbladder carcinoma patients and compared them with other prognostic parameters.

Materials and Methods

We enrolled 44 patients, who were initially diagnosed with gallbladder carcinoma and undergoing ¹⁸F-FDG PET/CT. Various metabolic volume-based PET parameters of primary tumors, including maximum and average standardized uptake values (SUV_max, SUV_avg), metabolic tumor volume (MTV), and total lesion glycolysis (TLG), were measured in gallbladder carcinoma patients using mediastinal blood pool activity as a threshold SUV for determining the tumor boundaries. Overall survival analysis was performed using the Kaplan-Meier method with PET parameters and other clinical variables. For determining independent prognostic factors, Cox proportional hazards regression analysis was performed.

Results

Of the 44 enrolled patients, cancer- or treatment-related death occurred in 30 (68.2 %). The mean clinical follow-up period was 22.2 ± 10.4 m (range, 0.6-35.9 m). Univariate analysis demonstrated that clinical or pathologic TNM stage (P < 0.001), treatment modality (P < 0.001), MTV (cutoff = 135 cm³, P = 0.001), and TLG (cutoff = 7,090, P < 0.05) were significant prognostic factors. In multivariate analysis, both clinical or pathologic TNM stage [hazard ratio (HR) = 2.019 (I vs II), 21.287 (I vs III), and 24.354 (I vs IV); P = 0.001) and TLG (HR = 2.930; P < 0.05) were independent prognostic factors for predicting overall survival.

Conclusions

In gallbladder cancer, TLG of the primary tumor, a volume-based metabolic parameter, is a significant independent prognostic factor for overall survival in conjunction with the clinical or pathological TNM stage.     

18F-FDG PET/CT is Useful for Pretreatment Assessment of the Histopathologic Type of Thymic Epithelial Tumors

Purpose

This study was performed to assess the usefulness of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) or PET/computed tomography (CT) for distinguishing thymic epithelial tumors according to World Health Organization (WHO) classifications.

Methods

We analyzed a total of 45 patients (range, 29–75 years of age; mean, 55 years) with pathologically confirmed thymic epithelial tumors who underwent pretreatment ¹⁸F-FDG PET or PET/CT between November 2003 and October 2009. The size, visual grading of uptake value, peak standardized uptake value (SUVpeak), uptake pattern, and contour of each tumor, and associated findings on PET or PET/CT, were analyzed relative to the three simplified WHO subgroups: less-invasive thymomas (types A and AB), more-invasive thymomas (types B1, B2, and B3) and thymic carcinomas. We statistically assessed the relationship of ¹⁸F-FDG PET or PET/CT findings with these simplified subgroups.

Results

Of the 45 patients, ten had less-invasive thymomas, 23 had more-invasive thymomas, and 12 had thymic carcinomas. The SUVpeak of the less- and more-invasive thymomas were significantly lower than those of thymic carcinomas (p < 0.000), but there was no difference in SUVpeak between less- and more-invasive thymomas. The visual grading scale (p < 0.000), uptake pattern (p = 0.001), and contour (p < 0.000) of the tumors differed significantly among the three simplified subgroups.

Conclusion

The image findings of ¹⁸F-FDG PET or PET/CT differed significantly by histologic subgroups. Pre-treatment evaluation with ¹⁸F-FDG PET or PET/CT might be helpful in differentiating subgroups of thymic epithelial tumors.     

Long-term changes of aortic 18F-FDG uptake and calcification in health-screening subjects

Background

We investigated long-term changes in aortic ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake and calcification in health-screening subjects and their relation with atherogenic risk factors.

Methods and results

A total of 94 consecutive subjects (72 men, 22 women; age 47–85 years, mean 57.9 years) participating in a health-screening protocol were evaluated retrospectively. All subjects had follow-up PET/CT scans 3.0–5.8 years (mean 4.1 years) later. We measured ¹⁸F-FDG uptake (maximum SUV) and calcium score (Agatston score) of the ascending, descending thoracic and infrarenal abdominal aorta on PET/CT images. ¹⁸F-FDG uptake and calcium score of the whole aorta (FUWA and CSWA) increased significantly in the follow-up study compared with the initial study (p = 0.02 and p < 0.0001, respectively). Multiple regression analysis showed that the change in FUWA per year was significantly associated with visceral fat area, while the change of CSWA per year was significantly associated with age and smoking habit. The degrees of ¹⁸F-FDG uptake and calcium score increases were significantly greater in the abdominal aorta than in the thoracic aorta (p = 0.05 and p < 0.0001, respectively).

Conclusions

Our data demonstrated the longitudinal progressions of vascular inflammation and calcification of health-screening subjects. Inflammation and calcification were observed to progress significantly faster in the abdominal aorta than in the thoracic aorta. The progressions of vascular inflammation and calcification may be associated with different atherogenic risk factors.     

18F-FDG Uptake of Human Testis on PET/CT: Correlation with Age,Sex Hormones,and Vasectomy

Purpose

The purpose of this study was to evaluate glucose metabolism of normal human testis on ¹⁸F-FDG PET/CT and to assess possible correlations among age, the serum levels of sex hormones, and vasectomy.

Methods

¹⁸F-FDG PET/CT was performed in 66 normal healthy men (50.8 ± 13.6 years, range 22–81), and mean standard uptake values (SUV) of ¹⁸F-FDG in testis and adductor muscle were measured. Testis-muscle SUV ratios (T/M ratios) were calculated. Serum levels of total testosterone, free testosterone, estradiol, and of sex-hormone binding globulin (SHBG) were measured. We searched for correlations between T/M ratios and age and the serum concentrations of sex hormones. ¹⁸F-FDG PET/CT was also performed in 32 vasectomized men (55.7 ± 7.8 years, range 38–71) and 52 nonvasectomized men (55.4 ± 11.6 years, range 37–72). Mean SUVs of testis and adductor muscle were measured, and T/M ratios were calculated.

Results

A significant age-related decline was found in T/M ratio (r = −0.509, p < 0.0001). Serum levels of total testosterone and free testosterone were also found to be positively correlated with T/M ratio (r = 0.427, p = 0.0003; r = 0.435, p = 0.0003, respectively). The mean SUV and T/M ratio of vasectomized men were significantly lower than those of nonvasectomized men (p < 0.0378 and p = 0.0001, respectively).

Conclusions

Glucose metabolism in the testis in an adult population was found to be correlated with age, serum sex hormone level, and vasectomy history. These results indicate that testicular ¹⁸F-FDG uptake may have attributed to testicular function and testicular histology. Our findings may have important implications for the interpretation of testicular ¹⁸F-FDG uptake in the normal adult population.     

Delayed sodium 18F-fluoride PET/CT imaging does not improve quantification of vascular calcification metabolism: Results from the CAMONA study

Background

This study aimed to determine if delayed sodium ¹⁸F-fluoride (Na¹⁸F) PET/CT imaging improves quantification of vascular calcification metabolism. Blood-pool activity can disturb the arterial Na¹⁸F signal. With time, blood-pool activity declines. Therefore, delayed imaging can potentially improve quantification of vascular calcification metabolism.

Methods and Results

Twenty healthy volunteers and 18 patients with chest pain were prospectively assessed by triple time-point PET/CT imaging at approximately 45, 90, and 180 minutes after Na¹⁸F administration. For each time point, global uptake of Na¹⁸F was determined in the coronary arteries and thoracic aorta by calculating the blood-pool-corrected maximum standardized uptake value (cSUV_MAX). A target-to-background ratio (TBR) was calculated to determine the contrast resolution at 45, 90, and 180 minutes. Furthermore, we assessed whether the acquisition time-point affected the relation between cSUV_MAX and the estimated 10-year risk for fatal cardiovascular disease (SCORE %). Coronary cSUV_MAX (P = .533) and aortic cSUV_MAX (P = .654) remained similar with time, whereas the coronary TBR (P < .0001) and aortic TBR (P < .0001) significantly increased with time. Even though the contrast resolution improved with time, positive correlations between SCORE % and coronary cSUV_MAX (P < .020) and aortic cSUV_MAX (P < .005) were observed at all investigated time points.

Conclusions

Delayed Na¹⁸F PET/CT imaging does not improve quantification of vascular calcification metabolism. Although contrast resolution improves with time, arterial Na¹⁸F avidity is invariant to the time between Na¹⁸F administration and PET/CT acquisition. Therefore, the optimal PET/CT acquisition time-point to quantify vascular calcification metabolism is achieved as early as 45 minutes after Na¹⁸F administration.     

Delayed 18F-fluorodeoxyglucose PET/CT imaging improves quantitation of atherosclerotic plaque inflammation: Results from the CAMONA study

Background

This study aimed to determine if delayed ¹⁸F-fluorodeoxyglucose (¹⁸FDG) PET/CT imaging improves quantitation of atherosclerotic plaque inflammation. Blood-pool activity can disturb the arterial ¹⁸FDG signal. With time, blood-pool activity declines. Therefore, delayed imaging can potentially improve quantitation of vascular inflammation.

Methods and Results

40 subjects were prospectively assessed by dual-time-point PET/CT imaging at approximately 90 and 180 minutes after ¹⁸FDG administration. For both time-points, global uptake of ¹⁸FDG was determined in the carotid arteries and thoracic aorta by calculating the blood-pool corrected maximum standardized uptake value (cSUV_MAX). A target-to-background ratio (TBR) was calculated to determine the contrast resolution at 90 and 180 minutes. Furthermore, we assessed whether the acquisition time-point affected the relation between cSUV_MAX and the estimated 10-year risk for fatal cardiovascular disease (SCORE %). A significant increase in carotid cSUV_MAX (23%, P < .0001), carotid TBR (20%, P < .0001), aortic cSUV_MAX (14%, P < .0001), and aortic TBR (20%, P < .0001) was observed with time. At 90 minutes, cSUV_MAX did not relate to SCORE %, whereas at 180 minutes significant positive relations were observed between SCORE % and carotid (τ = 0.25, P = .045) and aortic (τ = 0.33, P = .008) cSUV_MAX.

Conclusions

Delayed ¹⁸FDG PET/CT imaging at 180 minutes improves quantitation of atherosclerotic plaque inflammation over imaging at 90 minutes. Therefore, the optimal acquisition time-point to assess atherosclerotic plaque inflammation lies beyond the advocated time-point of 90 minutes after ¹⁸FDG administration.     

Incidental Focal 18F-FDG Uptake in the Prostate: Clinical Significance and Differential Diagnostic Criteria

Purpose

The extent and intensity of ¹⁸F-FDG uptake in prostate cancer patients are known to be variable, and the clinical significance of focal ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake that is incidentally found on positron emission tomography (PET) has not been established. We investigated the clinical significance of incidental focal prostate uptake of ¹⁸F-FDG on PET/computed tomography (CT) and analyzed differential findings on PET/CT between malignant and benign uptake.

Methods

A total of 14,854 whole-body ¹⁸F-FDG PET/CT scans (4,806 that were conducted during cancer screening and 10,048 that were conducted to evaluate suspected or alleged cancer outside of the prostate) were retrospectively reviewed to determine the presence, location, multiplicity and maximum standardized uptake value (SUVmax) of focal prostate uptake and combined calcification. The final diagnosis determined by serum prostate-specific antigen (PSA) level and biopsy was compared with PET findings.

Results

Incidental focal prostate uptake was observed in 148 of 14,854 scans (1.0 %). Sixty-seven of these 148 subjects who had diagnostic confirmation were selected for further analysis. Prostate cancer was diagnosed in nine of 67 subjects (13.4%). The remaining 58 subjects had no malignancy in the prostate based on normal serum PSA level (n = 53), or elevated serum PSA level with a negative biopsy result (n = 5). While 84.6% (11/13) of malignant uptake was peripherally located in the prostate glands, 60.2% (50/83) of benign uptake was centrally located (p < 0.05). The positive predictive value of peripheral focal uptake for malignancy was 25%. The SUVmax, multiplicity and combined calcification were not significantly different between the two groups.

Conclusion

Although incidental focal ¹⁸F-FDG uptake in the prostate is not common, the incidence of cancer with focal uptake is not low. Therefore, these findings deserve further evaluation. The location of the focal prostate uptake may help with the selection of high-risk prostate cancer patients.     

Validation of Simple Quantification Methods for 18F-FP-CIT PET Using Automatic Delineation of Volumes of Interest Based on Statistical Probabilistic Anatomical Mapping and Isocontour Margin Setting

Purpose

¹⁸F-FP-CIT positron emission tomography (PET) is an effective imaging for dopamine transporters. In usual clinical practice, ¹⁸F-FP-CIT PET is analyzed visually or quantified using manual delineation of a volume of interest (VOI) for the striatum. In this study, we suggested and validated two simple quantitative methods based on automatic VOI delineation using statistical probabilistic anatomical mapping (SPAM) and isocontour margin setting.

Methods

Seventy-five ¹⁸F-FP-CIT PET images acquired in routine clinical practice were used for this study. A study-specific image template was made and the subject images were normalized to the template. Afterwards, uptakes in the striatal regions and cerebellum were quantified using probabilistic VOI based on SPAM. A quantitative parameter, Q_SPAM, was calculated to simulate binding potential. Additionally, the functional volume of each striatal region and its uptake were measured in automatically delineated VOI using isocontour margin setting. Uptake-volume product (Q_UVP) was calculated for each striatal region. Q_SPAM and Q_UVP were compared with visual grading and the influence of cerebral atrophy on the measurements was tested.

Results

Image analyses were successful in all the cases. Both the Q_SPAM and Q_UVP were significantly different according to visual grading (P < 0.001). The agreements of Q_UVP or Q_SPAM with visual grading were slight to fair for the caudate nucleus (κ = 0.421 and 0.291, respectively) and good to perfect to the putamen (κ = 0.663 and 0.607, respectively). Also, Q_SPAM and Q_UVP had a significant correlation with each other (P < 0.001). Cerebral atrophy made a significant difference in Q_SPAM and Q_UVP of the caudate nuclei regions with decreased ¹⁸F-FP-CIT uptake.

Conclusion

Simple quantitative measurements of Q_SPAM and Q_UVP showed acceptable agreement with visual grading. Although Q_SPAM in some group may be influenced by cerebral atrophy, these simple methods are expected to be effective in the quantitative analysis of ¹⁸F-FP-CIT PET in usual clinical practice.     

The clinical effectiveness of reconstructing 18F-sodium fluoride PET/CT bone using Bayesian penalized likelihood algorithm for evaluation of metastatic bone disease in obese patients

Objective:A new Bayesian penalized likelihood reconstruction algorithm for positron emission tomography (PET) (Q.Clear) is now in clinical use for fludeoxyglucose (FDG) PET/CT. However, experience with non-FDG tracers and in special patient populations is limited. This pilot study aims to compare Q.Clear to standard PET reconstructions for ¹⁸F sodium fluoride (¹⁸F-NaF) PET in obese patients.Methods:30 whole body ¹⁸F-NaF PET/CT scans (10 patients with BMI 30–40 Kg/m² and 20 patients with BMI >40 Kg/m²) and a NEMA image quality phantom scans were analyzed using ordered subset expectation maximization (OSEM) and Q.Clear reconstructions methods with B400, 600, 800 and 1000. The images were assessed for overall image quality (IQ), noise level, background soft tissue, and lesion detectability, contrast recovery (CR), background variability (BV) and contrast-to-noise ratio (CNR) for both algorithms.Results:CNR for clinical cases was higher for Q.Clear than OSEM (p < 0.05). Mean CNR for OSEM was (21.62 ± 8.9), and for Q.Clear B400 (31.82 ± 14.6), B600 (35.54 ± 14.9), B800 (39.81 ± 16.1), and B1000 (40.9 ± 17.8). As the β value increased the CNR increased in all clinical cases. B600 was the preferred β value for reconstruction in obese patients. The phantom study showed Q.Clear reconstructions gave lower CR and lower BV than OSEM. The CNR for all spheres was significantly higher for Q.Clear (independent of β) than OSEM (p < 0.05), suggesting superiority of Q.Clear.Conclusion:This pilot clinical study shows that Q.Clear reconstruction algorithm improves overall IQ of ¹⁸F-NaF PET in obese patients. Our clinical and phantom measurement results demonstrate improved CNR and reduced BV when using Q.Clear. A β value of 600 is preferred for reconstructing ¹⁸F-NaF PET/CT with Q.Clear in obese patients.Advances in knowledge:¹⁸F-NaF PET/CT is less susceptible to artifacts induced by body habitus. Bayesian penalized likelihood reconstruction with¹⁸F-NaF PET improves overall IQ in obese patients.     

Impact of Nonosseous Findings on 18F-NaF PET/CT in a Patient with Ductal Breast Carcinoma

¹⁸F-NaF was used as a bone-seeking PET tracer for skeletal imaging until the introduction of the widely available ^99mTc-labeled bone agents. However, there is renewed clinical interest in ¹⁸F-NaF since prior technical and logistic limitations to its routine use are no longer present, and, as a consequence, it is likely that uptake unrelated to bone and non-osseous findings will be encountered more frequently. As a result of tumoral necrosis, soft tissue metastases may demonstrate ¹⁸F-NaF avidity due to dystrophic calcification. On the other hand, all non-osseous findings, whether ¹⁸F-NaF avid or not, may provide important diagnostic information that may alter the course of the disease, including treatment options. Herein we present a patient with ductal carcinoma of the breast in whom findings unrelated to the skeletal system in ¹⁸F-NaF PET/CT altered the treatment strategy.     

Relations Between Pathological Markers and Radioiodine Scan and 18F-FDG PET/CT Findings in Papillary Thyroid Cancer Patients With Recurrent Cervical Nodal Metastases

Purpose

The aim of this study was to investigate relationships between the immunohistochemical results and radioiodine scan and ¹⁸F-FDG PET findings in papillary thyroid cancer (PTC) patients with recurrent cervical nodal metastases.

Methods

A total of 46 PTC patients who had undergone a radioiodine scan and/or ¹⁸F-FDG PET/CT and a subsequent operation on recurrent cervical lymph nodes were enrolled. Twenty-seven patients underwent ¹⁸F-FDG PET/CT, 8 underwent radioiodine scans, and 11 underwent both scans. In all surgical specimens, the immunoexpressions of thyroglobulin (Tg), sodium-iodide symporter (NIS), glucose transporter 1 (Glut-1), and somatostatin receptor 1 and 2A (SSTR1 and SSTR2A) were assessed, and associations between these expressions and radioiodine scan and ¹⁸F-FDG PET findings were evaluated.

Results

Of the 38 patients who underwent ¹⁸F-FDG PET/CT, all patients with weak Tg expression had positive ¹⁸F-FDG uptake, while only 45 % of the patients with moderate or strong Tg expression showed positive uptake (p = 0.01). The proportion of patients with positive ¹⁸F-FDG uptake increased as the degree of Glut-1 expression with luminal accentuation increased. Of the 19 patients who underwent a radioiodine scan, the proportion with positive radioiodine uptake was greater among patients with strong NIS and SSTR2A expression than among patients expressing these markers at weak levels (p = 0.04 for all). All three patients with weak Tg expression were negative for radioiodine uptake.

Conclusion

The ¹⁸F-FDG uptakes of recurrent cervical nodes are related to strong Glut-1 expression with luminal accentuation and weak Tg expression, whereas radioiodine uptake is related to the strong expressions of NIS and SSTR2A.     

Diagnostic Performance of 68Ga-DOTATATE PET/CT, 18F-FDG PET/CT and 131I-MIBG Scintigraphy in Mapping Metastatic Pheochromocytoma and Paraganglioma

Purpose

To evaluate the diagnostic performance of ⁶⁸Ga-DOTATATE ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT), ¹⁸F-FDG PET/CT and ¹³¹I-MIBG scintigraphy in the mapping of metastatic pheochromocytoma and paraganglioma.

Materials and Methods

Seventeen patients (male = 8, female = 9; age range, 13–68 years) with clinically proven or suspicious metastatic pheochromocytoma or paraganglioma were included in this prospective study. Twelve patients underwent all three modalities, whereas five patients underwent ⁶⁸Ga-DOTATATE and ¹³¹I-MIBG without ¹⁸F-FDG. A composite reference standard derived from anatomical and functional imaging findings, along with histopathological information, was used to validate the findings. Results were analysed on a per-patient and on per-lesion basis. Sensitivity and accuracy were assessed using McNemar’s test.

Results

On a per-patient basis, 14/17 patients were detected in ⁶⁸Ga-DOTATATE, 7/17 patients in ¹³¹I-MIBG, and 10/12 patients in ¹⁸F-FDG. The sensitivity and accuracy of ⁶⁸Ga-DOTATATE, ¹³¹I-MIBG and ¹⁸F-FDG were (93.3 %, 94.1 %), (46.7 %, 52.9 %) and (90.9 %, 91.7 %) respectively. On a per-lesion basis, an overall of 472 positive lesions were detected; of which 432/472 were identified by ⁶⁸Ga-DOTATATE, 74/472 by ¹³¹I-MIBG, and 154/300 (patient, n = 12) by ¹⁸F-FDG. The sensitivity and accuracy of ⁶⁸Ga-DOTATATE, ¹³¹I-MIBG and ¹⁸F-FDG were (91.5 %, 92.6 % p < 0.0001), (15.7 %, 26.0 % p < 0.0001) and (51.3 %, 57.8 % p < 0.0001) respectively. Discordant lesions were demonstrated on ⁶⁸Ga-DOTATATE, ¹³¹I-MIBG and ¹⁸F-FDG.

Conclusions

Ga-DOTATATE PET/CT shows high diagnostic accuracy than ¹³¹I-MIBG scintigraphy and ¹⁸F-FDG PET/ CT in mapping metastatic pheochromocytoma and paraganglioma.     

Clinical Significance of Diffuse 18F-FDG Uptake in Residual Thyroid Gland after Unilateral Thyroid Lobectomy

Purpose

We investigated the clinical significance of diffuse uptake in remaining thyroid after unilateral lobectomy for thyroid cancer.

Methods

A total of 144 thyroid cancer patients who underwent ¹⁸F-FDG PET/CT after lobectomy were enrolled in the present study. The PET/CT images were evaluated for the presence of diffuse ¹⁸F-FDG uptake with maximum SUV (SUVmax) >2.0 in the residual thyroid and placed into one of two groups: with diffuse uptake and without diffuse uptake group. Clinical, laboratory, and PET/CT parameters in both groups were compared. Correlations between SUVmax of thyroid and available parameters were analyzed.

Results

Forty-two of 144 patients (29.2%) had diffuse thyroid uptake (mean SUVmax: 3.2 ± 1.1). All patients with diffuse uptake and 96 (94.1%) without diffuse uptake were receiving thyroxine therapy (P = 0.09). Thyroid function tests showed that most patients were euthyroid status (78.6 vs. 85.3%, P = 0.36). TgAb levels were significantly higher in patients with diffuse uptake (338.0 ± 664.6 vs. 57.3 ± 46.4, P < 0.0001). Mean attenuation values in the diffuse uptake group were significantly lower (72.2 ± 15. vs. 97.0 ± 16.0, P < 0.0001). An inverse correlation was found between SUVmax and mean attenuation values of residual thyroid in all patients (r = −0.57, P < 0.0001) and subgroup with diffuse uptake (r = −0.31, P < 0.05).

Conclusion

In this study, diffuse ¹⁸F-FDG uptake in the residual thyroid after unilateral lobectomy was a relatively frequent finding and may be associated with chronic thyroiditis. This uptake is not influenced by thyroid status or thyroxine therapy. The ¹⁸F-FDG uptake is inversely correlated with mean attenuation value of thyroid.     

Detection and global quantification of cardiovascular molecular calcification by fluoro18-fluoride positron emission tomography/computed tomography--a novel concept

The aim of this study was to examine the degree and prevalence of regional (aorta) and global (cardiac) fluorine-18-sodium fluoride ((18)F-NaF) uptake by positron emission tomography (PET)-computed tomography (CT) as evidence for calcification in the atherosclerotic plaques in the aorta and the heart as a function of age. Image data from 51 patients, who had undergone whole-body (18)F-NaF-PET/CT, were evaluated retrospectively. Cardiac and arterial (aorta) radiotracer uptakes were analyzed quantitatively by measuring standard uptake values (SUV). This approach involved examining the entire heart and various aortic segments as identified by CT. By combining CT and PET data, regional and global concentrations of this molecule were calculated and correlated with age over the decades. (18)F-NaF uptake in the heart and aorta increased significantly with advancing age (P<0.01). The Pearson correlation coefficient for the mean (18)F-NaF uptake of cardiac region and 5 age groups was 0.92 (P=0.003) and for aorta and 5 age groups was 0.97 (P=0.004). In conclusion, these preliminary data indicate the feasibility of (18)F-NaF-PET/CT for measurement of regional and global calcification of the heart and major arteries. The (18)F-NaF-PET/CT may provide highly relevant information about the state of calcified plaque before structural calcification is detectable by standard CT techniques. This, therefore, may allow for earlier intervention for risk reduction in cardiovascular diseases. Further studies are needed to validate the role of this promising technique in the management of patients with suspected atherosclerosis.     

Coronary artery calcium score on low-dose computed tomography for lung cancer screening

AIM: To evaluate the feasibility of coronary artery calcium score (CACS) on low-dose non-gated chest CT (ngCCT).METHODS: Sixty consecutive individuals (30 males; 73 ± 7 years) scheduled for risk stratification by means of unenhanced ECG-triggered cardiac computed tomography (gCCT) underwent additional unenhanced ngCCT. All CT scans were performed on a 64-slice CT scanner (Somatom Sensation 64 Cardiac, Siemens, Germany). CACS was calculated using conventional methods/scores (Volume, Mass, Agatston) as previously described in literature. The CACS value obtained were compared. The Mayo Clinic classification was used to stratify cardiovascular risk based on Agatston CACS. Differences and correlations between the two methods were compared. A P-value < 0.05 was considered significant.RESULTS: Mean CACS values were significantly higher for gCCT as compared to ngCCT (Volume: 418 ± 747 vs 332 ± 597; Mass: 89 ± 151 vs 78 ± 141; Agatston: 481 ± 854 vs 428 ± 776; P < 0.05). The correlation between the two values was always very high (Volume: r = 0.95; Mass: r = 0.97; Agatston: r = 0.98). Of the 6 patients with 0 Agatston score on gCCT, 2 (33%) showed an Agatston score > 0 in the ngCCT. Of the 3 patients with 1-10 Agatston score on gCCT, 1 (33%) showed an Agatston score of 0 in the ngCCT. Overall, 23 (38%) patients were reclassified in a different cardiovascular risk category, mostly (18/23; 78%) shifting to a lower risk in the ngCCT. The estimated radiation dose was significantly higher for gCCT (DLP 115.8 ± 50.7 vs 83.8 ± 16.3; Effective dose 1.6 ± 0.7 mSv vs 1.2 ± 0.2 mSv; P < 0.01).CONCLUSION: CACS assessment is feasible on ngCCT; the variability of CACS values and the associated re-stratification of patients in cardiovascular risk groups should be taken into account.     

Thoracic aorta calcification but not inflammation is associated with increased cardiovascular disease risk: results of the CAMONA study

Purpose

Arterial inflammation and vascular calcification are regarded as early prognostic markers of cardiovascular disease (CVD). In this study we investigated the relationship between CVD risk and arterial inflammation (¹⁸F-FDG PET/CT imaging), vascular calcification metabolism (Na¹⁸F PET/CT imaging), and vascular calcium burden (CT imaging) of the thoracic aorta in a population at low CVD risk.

Methods

Study participants underwent blood pressure measurements, blood analyses, and ¹⁸F-FDG and Na¹⁸F PET/CT imaging. In addition, the 10-year risk for development of CVD, based on the Framingham risk score (FRS), was estimated. CVD risk was compared across quartiles of thoracic aorta ¹⁸F-FDG uptake, Na¹⁸F uptake, and calcium burden on CT.

Results

A total of 139 subjects (52 % men, mean age 49 years, age range 21?–?75 years, median FRS 6 %) were evaluated. CVD risk was, on average, 3.7 times higher among subjects with thoracic aorta Na¹⁸F uptake in the highest quartile compared with those in the lowest quartile of the distribution (15.5 % vs. 4.2 %; P?<?0.001). CVD risk was on average, 3.7 times higher among subjects with a thoracic aorta calcium burden on CT in the highest quartile compared with those in the lowest two quartiles of the distribution (18.0 % vs. 4.9 %; P?<?0.001). CVD risk was similar in subjects in all quartiles of thoracic aorta ¹⁸F-FDG uptake.

Conclusion

Our findings indicate that an unfavourable CVD risk profile is associated with marked increases in vascular calcification metabolism and vascular calcium burden of the thoracic aorta, but not with arterial inflammation.

     

Correlation Between 18F-Fluorodeoxyglucose Uptake and Epidermal Growth Factor Receptor Mutations in Advanced Lung Cancer

Purpose

Mutations in the epidermal growth factor receptor (EGFR) gene have been identified as potential targets for the treatment and prognostic factors for non-small cell lung cancer (NSCLC). We assessed the correlation between fluorodeoxyglucose (FDG) uptake and EGFR mutations, as well as their prognostic implications.

Methods

A total of 163 patients with pathologically confirmed NSCLC were enrolled (99 males and 64 females; median age, 60 years). All patients underwent FDG positron emission tomography before treatment, and genetic studies of EGFR mutations were performed. The maximum standardized uptake value (SUVmax) of the primary lung cancer was measured and normalized with regard to liver uptake. The SUVmax between the wild-type and EGFR mutant groups was compared. Survival was evaluated according to SUVmax and EGFR mutation status.

Results

EGFR mutations were found in 57 patients (60.8 %). The SUVmax tended to be higher in wild-type than mutant tumors, but was not significantly different (11.1 ± 5.7 vs. 9.8 ± 4.4, P = 0.103). The SUVmax was significantly lower in patients with an exon 19 mutation than in those with either an exon 21 mutation or wild type (P = 0.003 and 0.009, respectively). The EGFR mutation showed prolonged overall survival (OS) compared to wild-type tumors (P = 0.004). There was no significant difference in survival according to SUVmax. Both OS and progression-free survival of patients with a mutation in exon 19 were significant longer than in patients with wild-type tumors.

Conclusion

In patients with NSCLC, a mutation in exon 19 was associated with a lower SUVmax and is a reliable predictor for good survival.