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Nuclear Medicine Communications - Current Issue

Nuclear Medicine Communications - Current Issue
  1. Effect of thyroid-stimulating hormone in 68Ga-DOTATATE PET/CT of radioiodine-refractory thyroid carcinoma: a pilot study
    imageBackground Radioiodine-refractory thyroid carcinomas (RAIRs) are characterized by reduced expression of sodium–iodine symporter, rising serum thyroglobulin levels, and negative whole-body radioiodine scans. Interestingly, RAIRs continue to express somatostatin receptors and can be identified with 68Ga-DOTATATE PET/CT imaging. Objective The objective of this study was to compare lesion detectability in 68Ga-DOTATATE PET/CT performed with elevated thyroid-stimulating hormone (eTSH) levels with suppressed thyroid-stimulating hormone (sTSH) levels. Patients and methods Fifteen patients with RAIR were prospectively enrolled in this pilot study. All patients underwent two 68Ga-DOTATATE PET/CT studies: with sTSH and with eTSH (after 30 days of levothyroxine withdrawal). All studies were blindly evaluated for differences pertaining to maximum standardized uptake values, detection of local recurrence, cervical lymph node (LN) metastases, cervical levels involved, distant LN metastases, lung metastases, and bone metastases. Reference standard consisted of fluorine-18-fluorodeoxyglucose PET/CT imaging, neck ultrasound, biopsy, and follow-up. Results 68Ga-DOTATATE PET/CT performed with both sTSH or eTSH was highly sensitive (91–100%) for detecting RAIR metastases. 68Ga-DOTATATE PET/CT with eTSH detected a higher total number of lesions (P=0.002), higher rate of cervical and distant LN metastases (P=0.002 and 0.0313, respectively), and significantly higher maximum standardized uptake values for cervical and distant LN metastases (P=0.0010 and 0.0078, respectively) when compared with sTSH. Conclusion 68Ga-DOTATATE PET/CT presents a high sensitivity in detecting metastatic lesions in patients with RAIR. Detectability increases with iodine-resistance, both with and without higher thyroid-stimulating hormone levels. These findings might improve staging and subsequent treatment planning, especially with radiolabeled somatostatin analogs.



  2. The predictive value for excellent response to initial therapy in differentiated thyroid cancer: preablation-stimulated thyroglobulin better than the TNM stage
    imagePurpose This study aimed to identify the predictive value of the low preablation-stimulated thyroglobulin (ps-Tg, <2 ng/ml) for excellent response to radioiodine remnant ablation in differentiated thyroid carcinoma. Patients and methods A total of 398 consecutive patients who underwent total thyroidectomy and radioactive iodine remnant ablation therapy were reviewed retrospectively. Each patient was risk-stratified using the American Joint Cancer Committee and risk staging systems and using response to the initial therapy reclassification system. ps-Tg was defined as less than 2 ng/ml with negative thyroglobulin antibody under thyroid-stimulating hormone stimulation. A multivariate analysis was carried out for ps-Tg, TNM stage, and other potential clinical and pathologic factors. Results We followed the patients for a median of 32.7 months. Overall, an excellent rate of response was achieved in 367 (92.2%) of the 398 patients. The only variable found to be associated with excellent response was ps-Tg (odds ratio=2.530, P=0.009) by multivariate analysis. The subgroups with 0


  3. The value of 99mTc-MDP bone SPECT/CT in evaluation of patients with painful knee prosthesis
    imageObjective The purpose of this study was to assess the incremental value of technetium-99m-methyl diphosphonate (99mTc-MDP) single-photon emission computed tomography/computed tomography (SPECT/CT) over 99mTc-MDP two-phase bone scan (TPBS) in the assessment of the patients with pain following knee arthroplasty. Patients and methods 99mTc-MDP TPBS and 99mTc-MDP SPECT/CT were performed in 49 patients with knee pain after knee arthroplasty. The scans were reviewed by two readers (nuclear medicine physician and musculoskeletal radiologist). 99mTc-MDP SPECT/CT studies were interpreted in conjunction with TPBS in this retrospective study to identify the pain generator in painful knee prosthesis. The final diagnosis was established based on a combination of histopathological/cytological findings, other imaging findings (e.g. MRI, radiolabelled white scan), clinical decisions, and management outcomes (including subsequent intraoperative findings). Results In diagnosing infection or aseptic loosening, a definitive outcome regarding the presence/absence of aseptic loosening or periprosthetic infection was obtained in 41 patients. (a) Sensitivity of 99mTc-MDP SPECT/CT [100%; 95% confidence interval (CI): 66.4–100%] was higher than 99mTc-MDP TPBS (88.9%; 95% CI: 51.8–99.7%). (b) Specificity of 99mTc-MDP SPECT/CT (75%; 95% CI: 53.3–90.2%) was considerably higher than 99mTc-MDP TPBS (30%; 95% CI: 11.9–54.3%). Alternative diagnoses were identified in 21/49 (43%) patients on 99mTc-MDP SPECT/CT, which could not be ascertained on 99mTc-MDP TPBS alone. Conclusion 99mTc-MDP SPECT/CT has better sensitivity and specificity compared with 99mTc-MDP TPBS in diagnosis of aseptic loosening and periprosthestic infection in patients with painful knee arthroplasty. 99mTc-MDP SPECT/CT identified alternative causes of pain in 43% of patients, which was not identified by 99mTc-MDP TPBS.



  4. Clinical role of bone scintigraphy in low-to-intermediate Framingham risk patients with atypical chest pain
    imageObjective The purpose of the study is to evaluate the clinical usefulness of bone scintigraphy for etiological diagnosis of patients with atypical chest pain. Patients and methods We retrospectively enrolled 225 patients with atypical chest pain who underwent bone scintigraphy for etiological diagnosis. No patients showed any symptoms or signs other than chest pain and had low-to-intermediate Framingham risk with insignificant findings on initial cardiac evaluation. They had no recent traumatic events or history of cerebrovascular and coronary heart diseases. The usefulness of bone scintigraphy for clinical diagnosis in enrolled patients was assessed and compared according to age (<60 vs. ≥60 years). Results Sixty-two (27.6%) patients were at intermediate Framingham risk and 100 (44.5%) patients were older than or equal to 60 years of age. Bone scintigraphy showed abnormal findings in 111 (49.4%) patients. Clinical diagnoses of chest pain were made in 163 (72.4%) patients. The remaining 62 (27.6%) patients were assessed as having unknown etiology. Bone scintigraphy was helpful for clinical diagnosis in 94 (41.8%) patients. Patients older than or equal to 60 years of age had significantly more frequent abnormal findings and post-traumatic changes on bone scintigraphy than patients younger than 60 years of age (P=0.010 for all). Of 111 patients with abnormal findings on bone scintigraphy, six (5.4%) were diagnosed with coronary heart disease; all of them were older than or equal to 60 years. Conclusion Bone scintigraphy was helpful for etiological diagnosis of atypical chest pain in 41.8% of patients. However, coronary heart disease should be considered in patients older than or equal to 60 years of age, even if patients showed abnormal findings on bone scintigraphy.



  5. Pretherapeutic 124I dosimetry reliably predicts intratherapeutic blood kinetics of 131I in patients with differentiated thyroid carcinoma receiving high therapeutic activities
    imageAim The aim of this study was to assess the agreement between predicted blood uptake values using 124I and actually measured 131I blood uptake values (reference) in patients with differentiated thyroid carcinoma receiving largely high therapeutic activities. Patients and methods Fourteen patients were analyzed retrospectively, who underwent a series of both pretherapeutic and intratherapeutic blood sampling using median 124I activities of 23 MBq and median therapy 131I activities of 10 GBq. Data of five blood samples from each patient were analyzed. Lin’s concordance correlation coefficient analysis was carried out to assess the kinetic agreement. The time-integrated 131I activity coefficient (TIAC) for the blood compartment and the effective 131I clearance time (ECT), expressed as effective 131I half-life on the basis of a monoexponential model, were ascertained. For each patient, the (intrapatient) percentage differences between pretherapeutic and intratherapeutic TIACs and ECTs were calculated. The (interpatient) difference in TIACs and ECTs between pretherapy and intratherapy groups was evaluated using the Mann–Whitney U-test. Results Lin’s concordance correlation coefficient was at least 0.97, indicating substantial kinetic agreement between pretherapeutic and intratherapeutic radioiodine kinetics. The mean (median)±SD (range) of the absolute percentage difference was 9% (11%)±7% (0.33–20%) for the TIAC and 11% (10%)±10% (0–23%) for the ECT. A slightly higher median TIAC was observed in intratherapy (2.8 vs. 3.3 h), but this was not statistically significant (P=0.15), whereas no remarkable ECT difference (P=0.62) was found. Conclusion The pretherapeutic blood kinetics derived from diagnostic 124I activities provides a reliable estimation of the intratherapeutic 131I blood kinetics in patients receiving largely high therapy activities, showing its potential for radioiodine treatment planning.


  6. Effects of hyperglycemia on fluorine-18-fluorodeoxyglucose biodistribution in a large oncology clinical practice
    imageAim Suggested cutoff points of blood glucose levels (BGL) before 18F-FDG PET/CT scanning vary between 120 and 200 mg/dl in current guidelines. This study’s purpose was to compare the frequency of abnormal fluorine-18-fluorodeoxyglucose (18F-FDG) biodistribution on PET/CT scans of patients with various ranges of abnormal BGL and to determine the effect of BGL greater than 200 mg/dl on 18F-FDG uptake in various organs. Patients and methods 18F-FDG PET/CT scans were retrospectively reviewed for 325 patients with BGL greater than 120 mg/dl at the time of scan and 112 with BGL less than or equal to 120 mg/dl. 18F-FDG biodistribution was categorized as normal, mildly abnormal, or abnormal by visual analysis of brain, background soft tissue, and muscle. Mean standardized uptake values (SUVmean) in brain, liver, fat (flank), gluteal muscle, and blood pool (aorta) were recorded. 18F-FDG biodistribution frequencies were assessed using a nonparametric χ2-test for trend. Normal organ SUVs were compared using Kruskal–Wallis tests using the following BGL groupings: ≤120, 121–150, 151–200, and ≥201 mg/dl. Results Although higher BGL were significantly associated with an increased proportion of abnormal biodistribution (P<0.001), most patients with BGL less than or equal to 200 mg/dl had normal or mildly abnormal biodistribution. Average brain SUVmean significantly decreased with higher BGL groupings (P<0.001). Average aorta, gluteal muscle, and liver SUVmean did not significantly differ among groups with BGL greater than 120 mg/dl (P=0.66, 0.84, and 0.39, respectively), but were significantly lower in those with BGL less than or equal to 120 mg/dl (P≤0.001). Flank fat SUVmean was not significantly different among BGL groups (P=0.67). Conclusion Abnormal 18F-FDG biodistribution is associated with higher BGL at the time of scan, but the effects are negligible or mild in most patients with BGL less than 200 mg/dl. Although mildly increased soft tissue uptake is seen with BGL greater than 120 mg/dl, decline in brain metabolic activity correlated the most with various BGL.



  7. Contrast-enhanced computed tomography does not improve the diagnostic value of parathyroid dual-phase MIBI SPECT/CT
    imageObjective The aim of this study was to investigate the contribution of contrast-enhanced computed tomography (CE-CT) to the localization of parathyroid adenomas compared with the dual-phase Tc-99m MIBI SPECT with low-dose CT (LD-CT). Patients and methods This retrospective study included consecutive patients with primary hyperparathyroidism who underwent a preoperative dual-phase MIBI SPECT/CT followed by surgical resection. The standard of care was dual-phase MIBI SPECT/CT, acquired with LD-CT in the early phase and CE-CT in the late phase (SPECT/CE-CT). The presence and localization of positive sites were extracted from study reports. To examine the role of CE-CT, patient cases were independently re-reviewed, with the early LD-CT fused with early and late SPECT (SPECT/LD-CT). The two SPECT/CT methods were compared for sensitivity, and the positive predictive value and histopathology were used as a reference. Results In total, 138 patients were included. The investigation was positive for suspected adenomas in 124 patients using SPECT/CE-CT and in 122 patients using SPECT/LD-CT. The per-patient sensitivity was 87.5% [95% confidence interval (CI): 80.7–92.6%] for SPECT/CE-CT and was not statistically significantly different from SPECT/LD-CT (85.3%; 95% CI: 78.2–90.8%) (P=0.39). The positive predictive value was 95.2% (95% CI: 95.4–99.9%) with SPECT/CE-CT versus 100% (95% CI: 96.8–100%) with SPECT/LD-CT. For small adenomas (≤500 mg), the sensitivity was low with SPECT/CE-CT (67%) as well as with SPECT/LD-CT (64%). Conclusion Late CE-CT, compared with late LD-CT, did not significantly improve the sensitivity of dual-phase Tc-99m MIBI parathyroid SPECT/CT in a population of patients with primary hyperparathyroidism. These findings were consistent regardless of the size, location, or histology of the adenomas.



  8. Predictive and prognostic value of left ventricular mechanical dyssynchrony assessed by myocardial perfusion single photon emission computed tomography in asymptomatic patients under hemodialysis
    imageBackground Patients under hemodialysis (HD) have an increased risk of major adverse cardiac events (MACEs). In these patients, myocardial perfusion scintigraphy (MPS) provides useful prognostic information. Left ventricular mechanical dyssynchrony (LVD) has been proven to predict all-cause death in patients under HD. It remains unclear, whether the same prognostic value pertains also to the prediction of MACEs. Patients and methods Ninety patients under HD (duration range: 2–216 months) with neither history nor symptoms of coronary artery disease at the time of MPS were retrospectively evaluated. All underwent clinical evaluation and MPS with dipyridamole stress test. MPS was reprocessed to derive left ventricular ejection fraction (EF), perfusion scores [summed stress score (SSS) and summed difference score (SDS)] and LVD (phase histogram bandwidth and phase SD). Results MACEs were reported in 10 (11.1%) patients as assessed at more than 2 years of follow-up (median 29 months). At univariate analysis, a correlation was demonstrated between MACEs and LVD (P<0.001), BMI (P=0.04), ECG changes during stress (P=0.03), dyspnea (P=0.02), SSS (P=0.04) and SDS (P=0.02). At stepwise multivariate analysis, only LVD (P<0.001), SSS (P=0.01) and SDS (P=0.001) were independent predictors of MACEs. No thresholds of SSS or SDS showed predictive value (P=0.79 for SSS ≥4, P=0.10 for SSS >8 and P=0.66 for SDS ≥2). At survival analysis, patients with LVD had a significantly shorter MACE-free survival (P<0.001). This predictive value held true even in patients with an unremarkable pattern of perfusion. Conclusion In asymptomatic patients without known coronary artery disease under HD, LVD is highly predictive of the onset of MACEs at more than 2 years of follow-up and provides incremental value over perfusion scores alone. A phase analysis on gated MPS should be routinely performed in these patients to yield useful prognostic information.



  9. A novel method to assess subchondral bone formation using [18F]NaF-PET in the evaluation of knee degeneration
    imagePurpose Fluorine-18-sodium fluoride-PET ([18F]NaF-PET) facilitates direct assessment of subchondral bone formation to evaluate degeneration in articulating joints. No standards exist for the quantification of joint activity using [18F]NaF-PET, and many techniques rely on focal uptake to characterize an entire region of interest. This study proposes a novel method of quantitative global knee analysis to assess regions of expected bone remodeling in the evaluation of knee degeneration. Patients and methods The study population consisted of 18 patients with rheumatoid arthritis who underwent [18F]NaF-PET/computed tomography imaging. The maximum standardized uptake value (knee SUVmax) in addition to a target-to-background ratio (TBR) that represents global knee activity adjusted for systemic bone formation measured at the lateral femoral neck (global knee TBR) were calculated. A radiologist scored standard radiographs of the knee in nine patients using the Kellgren–Lawrence grading system. Results Patients with greater [18F]NaF uptake demonstrated greater knee deterioration, which was corroborated by the radiograph findings. Average Kellgren–Lawrence grading was strongly associated with both global knee TBR (Spearman ρ=0.69, P=0.04) and knee SUVmax scores (Spearman ρ=0.93, P=0.0003). Conclusion Assessment of global activity within the joint is a feasible and clinically useful technique for characterizing disease activity with a single value. Furthermore, a ratio based on systemic bone turnover in a nonarticulating, weight-bearing site adjusts for differences in bone formation related to bodyweight or metabolic bone diseases. We hypothesize that a global knee TBR score may be more sensitive at detecting changes in disease progression, as new spatially distinct lesions with a lower SUV that develop within an region of interest would not be detected by the SUVmax methodology. Longitudinal studies assessing sensitivity with larger patient cohorts are needed to further validate this methodology.



  10. Pilocarpine effect on dose rate of salivary gland in differentiated thyroid carcinoma patients treated with radioiodine
    imageObjective Although different methods have been suggested on reducing salivary gland radiation after radioiodine administration, an effective preventive or therapeutic measure is still up for debate. The aim of this study was to evaluate the effect of pilocarpine, as a sialagogue drug on the radioiodine content of the salivary gland, and radioiodine-induced symptoms of salivary gland dysfunction. Patients and methods Patients who were referred for radioiodine therapy were randomized into pilocarpine and placebo groups. The patients as well as the nurse who administered the tablets, and the specialist who analyzed the images, were all unaware of the patients’ group. Anterior and posterior planar images including that of both the head and neck were obtained 2, 6, 12, 24, and 48 h after the administration of radioiodine in all patients, and round regions of interest were drawn for both left and right parotid glands, with a rectangular region of interest in the region of the cerebrum as background. All patients were interrogated once, 6 months after radioiodine administration, by a phone call for subjective evaluation of symptoms related to salivary gland damage. Results There was no significant difference between the two groups with regard to the mean age, sex, and initial iodine activity. The geometric mean of background-corrected count per administered dose and acquisition time was calculated for the bilateral parotid glands. This normalized parotid count showed a significant reduction in net parotid count in both groups during the first 48 h after radioiodine administration. However, no significant difference was found between the groups according to the amount and pattern of dose reduction in this time period. Conclusion This study revealed that pilocarpine had no significant effect on the radioiodine content of parotid glands during the first 48 h after radioiodine administration. No significant difference was found in the incidence of symptoms between the two groups treated with placebo and pilocarpine.


  11. A comparison of four-sample slope–intercept and single-sample 51Cr-EDTA glomerular filtration rate measurements
    imageThe aim of this study was to verify, with a large dataset of 1394 51Cr-EDTA glomerular filtration rate (GFR) studies, the equivalence of slope–intercept and single-sample GFR. Raw data from 1394 patient studies were used to calculate four-sample slope–intercept GFR in addition to four individual single-sample GFR values (blood samples taken at 90, 150, 210 and 270 min after injection). The percentage differences between the four-sample slope–intercept and each of the single-sample GFR values were calculated, to identify the optimum single-sample time point. Having identified the optimum time point, the percentage difference between the slope–intercept and optimal single-sample GFR was calculated across a range of GFR values to investigate whether there was a GFR value below which the two methodologies cannot be considered equivalent. It was found that the lowest percentage difference between slope–intercept and single-sample GFR was for the third blood sample, taken at 210 min after injection. The median percentage difference was 2.5% and only 6.9% of patient studies had a percentage difference greater than 10%. Above a GFR value of 30 ml/min/1.73 m2, the median percentage difference between the slope–intercept and optimal single-sample GFR values was below 10%, and so it was concluded that, above this value, the two techniques are sufficiently equivalent. This study supports the recommendation of performing single-sample GFR measurements for GFRs greater than 30 ml/min/1.73 m2.



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