Biodistribution,radiation dosimetry and scouting of <Superscript>90</Superscript>Y-ibritumomab tiuxetan therapy in patients with relapsed B-cell non-Hodgkin’s lymphoma using <Superscript>89</Superscript>Zr-ibritumomab tiuxetan and PET

Purpose  

Positron emission tomography (PET) with ⁸⁹Zr-ibritumomab tiuxetan can be used to monitor biodistribution of ⁹⁰Y-ibritumomab tiuxetan as shown in mice. The aim of this study was to assess biodistribution and radiation dosimetry of ⁹⁰Y-ibritumomab tiuxetan in humans on the basis of ⁸⁹Zr-ibritumomab tiuxetan imaging, to evaluate whether co-injection of a therapeutic amount of ⁹⁰Y-ibritumomab tiuxetan influences biodistribution of ⁸⁹Zr-ibritumomab tiuxetan and whether pre-therapy scout scans with ⁸⁹Zr-ibritumomab tiuxetan can be used to predict biodistribution of ⁹⁰Y-ibritumomab tiuxetan and the dose-limiting organ during therapy.     

Detection of bone marrow and extramedullary involvement in patients with non-Hodgkin’s lymphoma by whole-body MRI: comparison with bone and <Superscript>67</Superscript>Ga scintigraphies

The aim of this study was to evaluate the diagnostic potential of whole-body MRI (WB-MRI) for the detection of bone marrow and extramedullary involvement in patients with non-Hodgkins lymphoma. WB-MRI, which was performed on 34 patients, consisted of the recording of T1-weighted spin-echo images and a fast STIR sequence covering the entire skeleton. The WB-MRI findings for bone marrow and extramedullary involvement were compared with those from ⁶⁷Ga and bone scintigraphies and bone marrow biopsy results. Two MRI specialists reviewed the WB-MRI results and two expert radiologists in the field of nuclear medicine reviewed the bone and ⁶⁷Ga scintigraphy findings. Bone marrow and extramedullary involvement of non-Hodgkins lymphoma were confirmed by follow-up radiographs and CT and/or a histological biopsy. The detection rate of WB-MRI was high. More bone marrow involvement was detected by biopsy, and more lesions were detected by scintigraphies. In total, 89 lesions were detected by WB-MRI, whereas 15 were found by biopsy, 5 by ⁶⁷Ga scintigraphy, and 14 by bone scintigraphy. WB-MRI could also detect more extramedullary lesions than ⁶⁷Ga scintigraphy; i.e., 72 lesions were detected by WB-MRI, whereas 54 were discovered by ⁶⁷Ga scintigraphy. WB-MRI is useful for evaluating the involvement of bone marrow and extramedullary lesions throughout the skeleton in patients with non-Hodgkins lymphoma.     

<Superscript>18</Superscript>p-FDG PET is superior to<Superscript>67</Superscript>Ga SPECT in the staging of non-Hodgkin’s lymphoma

OBJECTIVE: Our study aims to compare diagnostic accuracy between 18F-FDG PET and 67Ga SPECT in the staging of non-Hodgkin's lymphoma. METHODS: Twenty-eight patients with non-Hodgkin's lymphoma, underwent 18F-FDG PET, 67Ga SPECT and CT for the pretreatment staging of malignant lymphoma between August 1999 and March 2002. 18F-FDG PET imaging was obtained 60 minutes after the intravenous administration of 185 MBq of 18F-FDG. 67Ga SPECT imaging was obtained 2 days after the intravenous administration of 148 MBq of 67Ga. 18F-FDG PET and 67Ga SPECT were performed within one month. Both imagings were performed on the area from the neck to the pelvis. The 18F-FDG PET and 67Ga SPECT findings were compared with the CT findings and the clinical course. RESULTS: Sixty-six nodal lesions were clinically confirmed. Of these, 32 were identified by both 18F-FDG PET and 67Ga SPECT. The remaining 34 lesions were identified only by 18F-FDG PET. The mean (+/- SD) sizes' of the nodes were 34.7 +/- 32.4 mm for 18F-FDG-positive and 67Ga-positive lesions and 15.7 +/- 8.3 mm for 18F-FDG-positive and 67Ga-negative lesions (p < 0.001). Of the 23 extranodal lesions, 12 were identified by both 18F-FDG PET and 67Ga SPECT, whereas 6 lesions were identified by only 18F-FDG PET. Five lesions were not identified by either technique. No 18F-FDG-negative but 67Ga-positive nodal or extranodal lesions were observed. The difference in findings between the two studies is related to the difference in the size but not in the histology or site of the lesions. CONCLUSION: 18F-FDG PET detected significantly more lesions particularly small lesions than 67Ga SPECT. Thus, 18F-FDG PET is considered to be superior to 67Ga SPECT in the staging of non-Hodgkin' s lymphoma.     

Bio-effect model applied to <Superscript>131</Superscript>I radioimmunotherapy of refractory non-Hodgkin’s lymphoma

Purpose  

Improved data collection methods have improved absorbed dose estimation by tracking activity distributions and tumor extent at multiple time points, allowing individualized absorbed dose estimation. Treatment with tositumomab and ¹³¹I-tositumomab anti-CD20 radioimmunotherapy (BEXXAR) yields a cold antibody antitumor response (cold protein effect) and a radiation response. Biologically effective contributions, including the cold protein effect, are included in an equivalent biological effect model that was fit to patient data.     

<Superscript>18</Superscript>F-FDG PET/CT metabolic tumor parameters and radiomics features in aggressive non-Hodgkin’s lymphoma as predictors of treatment outcome and survival

Purpose

To determine whether metabolic tumor parameters and radiomic features extracted from ¹⁸F-FDG PET/CT (PET) can predict response to therapy and outcome in patients with aggressive B-cell lymphoma.

Methods

This institutional ethics board-approved retrospective study included 82 patients undergoing PET for aggressive B-cell lymphoma staging. Whole-body metabolic tumor volume (MTV) using various thresholds and tumor radiomic features were assessed on representative tumor sites. The extracted features were correlated with treatment response, disease-free survival (DFS) and overall survival (OS).

Results

At the end of therapy, 66 patients (80.5%) had shown complete response to therapy. The parameters correlating with response to therapy were bulky disease?>?6 cm at baseline (p?=?0.026), absence of a residual mass?>?1.5 cm at the end of therapy CT (p?=?0.028) and whole-body MTV with best performance using an SUV threshold of 3 and 6 (p?=?0.015 and 0.009, respectively). None of the tumor texture features were predictive of first-line therapy response, while a few of them including GLNU correlated with disease-free survival (p?=?0.013) and kurtosis correlated with overall survival (p?=?0.035).

Conclusions

Whole-body MTV correlates with response to therapy in patient with aggressive B-cell lymphoma. Tumor texture features could not predict therapy response, although several features correlated with the presence of a residual mass at the end of therapy CT and others correlated with disease-free and overall survival. These parameters should be prospectively validated in a larger cohort to confirm clinical prognostication.

     

Early therapy monitoring with FDG-PET in aggressive non-Hodgkin’s lymphoma and Hodgkin’s lymphoma

This study was designed to determine the value of 2-[fluorine-18]-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) in the early assessment of therapy response in lymphoma patients. We studied 20 patients with pathologically proven lymphoma, including 17 patients with aggressive non-Hodgkins lymphoma and three patients with Hodgkins lymphoma. All patients underwent whole-body FDG-PET imaging at baseline and after 1–2 cycles of chemotherapy. PET images were analysed visually and quantitatively by calculating the standardised uptake value (SUV). In each patient, we measured the SUV of the tumour demonstrating the highest FDG uptake at baseline study and the SUV of the same tumour after 1–2 cycles of therapy. The achievement of complete response was assessed on the basis of a combination of clinical findings and the results of conventional imaging modalities. Follow-up of progression-free survival (PFS) was obtained for the validation of PET data. Of the 20 patients, ten achieved complete remission at the completion of chemotherapy and the other ten did not respond to chemotherapy. Of the ten responders, four are still in remission (PFS 24–34 months) while the other six have relapsed (PFS 8–16 months). For the prediction of 24-month clinical outcome, visual analysis of PET after 1–2 cycles showed high sensitivity (87.5%) and accuracy (80%) but low specificity (50%). Comparison with the baseline SUVs revealed that the responders showed a significantly greater percent reduction in SUV after 1–2 cycles of therapy as compared with the non-responders (81.2%±9.5% vs 35.0%±20.2%, P<0.001). In addition, using 60% reduction as a cut-off value, the responders were clearly separated from the non-responders, with the exception of one non-responder. In conclusion, when performed early during chemotherapy, FDG-PET may be predictive of clinical outcome and allows differentiation of responders from non-responders in cases of aggressive lymphoma.     

Decreased brain FDG uptake in patients with extensive non-Hodgkin’s lymphoma lesions

Objective  

Faint brain [¹⁸F]fluoro-2-deoxyglucose (FDG) uptake has sporadically been reported in patients with FDG-avid large or diffusely extended tumors. The purpose of this study was to investigate whether there is a correlation between massive tumor uptake and decreased brain uptake on FDG positron emission tomography/computed tomography (PET/CT).     

Clinical correlation of the binding potential with <Superscript>123</Superscript>I-FP-CIT in de novo idiopathic Parkinson’s disease patients

Purpose  The aim of this study was to evaluate the accuracy of different single-photon emission computed tomography (SPECT) reconstruction techniques in measuring striatal N-ω-fluoropropyl-2β-carbomethoxy-3β-4-[¹²³I]iodophenyl-nortropane (¹²³I-FP-CIT) binding in de novo Parkinson’s disease (PD) patients, in order to find a correlation with clinical scales of disease severity in the initial phases of disease. Methods  Thirty-six de novo PD patients underwent ¹²³I-FP-CIT SPECT and MRI scan. SPECT data were reconstructed with filtered back projection (FBP), with an iterative algorithm (ordered subset expected maximization, OSEM) and with a method previously developed in our institution, called least-squares (LS) method. The ratio of specific to non-specific striatal ¹²³I-FP-CIT binding (binding potential, BP) was used as the outcome measure with all the reconstruction methods (BP_FBP, BP_OSEM, BP_LS). Results  The range of values of striatal BP_LS was significantly greater than BP_FBP and BP_OSEM. For all striatal regions, estimates of BP_FBP correlated well with BP_OSEM (r = 0.84) and with BP_LS (r = 0.64); BP_OSEM correlated significantly with BP_LS (r = 0.76). A good correlation was found between putaminal BP_LS and Hoen and Yahr, Unified PD Rating Scale (UPDRS) and lateralized UPDRS motor scores (r = −0.46, r = −0.42, r = −0.39, respectively). Neither putaminal BP_FBP nor putaminal BP_OSEM correlated with any of these motor scores. Conclusions  In de novo PD patients, ¹²³I-FP-CIT BP values derived from FBP and OSEM reconstruction techniques do not permit to differentiate PD severity. The LS method instead finds a correlation between striatal BP and disease severity scores. The results of this study support the use of ¹²³I-FP-CIT BP values estimated with the LS method as a biomarker of PD severity.     

Five-year follow-up of <Superscript>11</Superscript>C-PIB uptake in Alzheimer’s disease and MCI

Purpose

The aim of this study was to evaluate the longitudinal changes in [¹¹C]PIB uptake in mild cognitive impairment (MCI) and Alzheimer’s disease (AD) over a long-term follow-up.

Methods

Six AD patients, ten MCI patients and eight healthy subjects underwent a [¹¹C]PIB PET scan at baseline and at 2 and 5 years. The clinical status of the MCI patients was evaluated every 6 months.

Results

The MCI group showed a significant increase in [¹¹C]PIB uptake over time (p?<?0.001), with a similar increase from baseline to 2 years (4.7 % per year) and from 2 to 5 years (5.0 % per year). Eight MCI patients (80 %) converted to AD, and two of these patients showed a normal [¹¹C]PIB scan at baseline but increased uptake later. There was an increase in [¹¹C]PIB uptake with time in the AD group (p?=?0.02), but this did not significantly differ from the change in the control group.

Conclusion

Our results revealed a significant increase in amyloid load even at the time of AD diagnosis in some of the MCI patients who converted. A positive [¹¹C]PIB scan at baseline in MCI patients strongly predicted future conversion to AD but a negative PIB scan in MCI patients did not exclude future conversion. The results suggest that there is wide individual variation in the brain amyloid load in MCI, and in the course of amyloid accumulation in relation to the clinical diagnosis of AD.

     

Quantitative evaluation of tau PET tracers <Superscript>18</Superscript>F-THK5351 and <Superscript>18</Superscript>F-AV-1451 in Alzheimer’s disease with standardized uptake value peak-alignment (SUVP) normalization

Purpose

Off-target binding in the reference region is a challenge for recent tau tracers ¹⁸F-AV-1451 and ¹⁸F-THK5351. The conventional standardized uptake value ratio (SUVR) method relies on the average uptake from an unaffected tissue sample, and therefore is susceptible to biases from off-target binding as well as variability among individuals in the reference region. We propose a new method, standardized uptake value peak-alignment (SUVP), to reduce the bias of the SUVR, and improve the quantitative assessment of tau deposition.

Methods

The SUVP normalizes uptake values by their mode and standard deviation. Instead of using a reference region, the SUVP derives the contrast from unaffected voxels over the whole brain. Using SUVP and SUVR methods, we evaluated the global and regional tau binding of ¹⁸F-THK5351 and ¹⁸F-AV-1451 on two independent cohorts (N?=?18 and 32, respectively), each with cognitively normal (NL) subjects and Alzheimer’s disease (AD) subjects.

Results

Both tracers showed significantly increased binding for AD in the targeted cortical areas. In the temporal cortex, SUVP had a higher classification success rate (CSR) than SUVR (0.96 vs 0.89 for ¹⁸F-THK5351; 0.86 vs 0.75 for ¹⁸F-AV-1451), as well as higher specificity under fixed sensitivity around 0.80 (0.70 vs 0.45 specificity for ¹⁸F-THK5351; 1.00 vs 0.78 for ¹⁸F-AV-1451). In the cerebellar cortex, an AD-NL group difference with effect size (Cohen’s d) of 0.62 was observed for AV-1451, confirming the limitation of the SUVR approach using this region as a reference. A smaller cerebellar effect size (0.09) was observed for THK5351.

Conclusion

The SUVP method reduces the bias of the reference region and improves the NL-AD classification compared to the SUVR approach.

     

Clinical results of radionuclide therapy of neuroendocrine tumours with <Superscript>90</Superscript>Y-DOTATATE and tandem <Superscript>90</Superscript>Y/<Superscript>177</Superscript>Lu-DOTATATE: which is a better therapy option?

Purpose  

Peptide receptor radionuclide therapy (PRRT) using radiolabelled somatostatin analogues is a treatment option for patients with disseminated neuroendocrine tumours (NET). A combination treatment using the high-energy ⁹⁰Y beta emitter for larger lesions and the lower energy ¹⁷⁷Lu for smaller lesions has been postulated in the literature.The aim of the study was to evaluate combined ⁹⁰Y/¹⁷⁷Lu-DOTATATE therapy in comparison to ⁹⁰Y-DOTATATE alone.     

Diagnosis and staging of children’s lymphoma using the technetium-labelled somatostatin analogue, <Superscript>99m</Superscript>Tc-depreotide

Somatostatin receptor scintigraphy (SRS) is useful in diagnosing tumours with increased expression of somatostatin receptors. Lymphoma cells are known to express somatostatin receptors; however, the application of indium-labelled analogues in children is limited. The aim of this study was to investigate whether the technetium-labelled somatostatin analogue, depreotide, may be useful in diagnosing and staging malignant lymphoma in children. Fifteen children (mean age 13.8 years) with malignant lymphoma were studied (eight with Hodgkins lymphoma and seven with non-Hodgkins lymphoma). All children were investigated for verification of staging established by other modalities. Imaging was performed 3–5 h after administration of 300–550 MBq ^99mTc-depreotide. All patients underwent whole-body scan and single-photon emission tomography of the chest and/or abdomen. Images were assessed visually. In all patients, foci of increased tracer uptake were found. The neck and thorax were the most frequent lesion localisations. Abdominal lesions were found in four patients, and bone lesions in three. In two patients, diffusely increased uptake was observed throughout the skeleton (verified as representing bone marrow involvement). In 11 patients, the number of abnormal sites detected by SRS was greater than that detected by CT. Based on radionuclide examination, three children were upstaged and none were downstaged. It is concluded that ^99mTc-depreotide shows increased accumulation in pathological sites in malignant lymphoma in children. SRS with ^99mTc-depreotide provides a single-day imaging method with high sensitivity in lymphoma and with all the advantages of a technetium-labelled compound. Further studies are required on the specificity and the possible value of ^99mTc-depreotide in the follow-up of these patients.     

Detection of bone metastases in patients with prostate cancer by <Superscript>18</Superscript>F fluorocholine and <Superscript>18</Superscript>F fluoride PET–CT: a comparative study

Purpose  The aim of this prospective study was to compare the potential value of ¹⁸F fluorocholine (FCH) and ¹⁸F fluoride positron emission tomography (PET)–CT scanning for the detection of bony metastases from prostate cancer. Methods  Thirty-eight men (mean age, 69 ± 8 years) with biopsy-proven prostate cancer underwent both imaging modalities within a maximum interval of 2 weeks. Seventeen patients were evaluated preoperatively, and 21 patients were referred for post-operative evaluation of suspected recurrence or progression based on clinical algorithms. The number, sites and morphological patterns of bone lesions on ¹⁸F FCH and ¹⁸F fluoride PET–CT were correlated: Concordant lesions between the two modalities with corresponding changes on CT were considered to be positive for malignancy; discordant lesions were verified by follow-up examinations. The mean follow-up interval was 9.1 months. Results  Overall, 321 lesions were evaluated in this study. In a lesion-based analysis, a relatively close agreement was found between these two imaging modalities for detection of malignant bone lesions (kappa = 0.57), as well as in a patient-based analysis (kappa = 0.76). Sixteen malignant sclerotic lesions with a high density were negative in both ¹⁸F FCH and ¹⁸F fluoride PET–CT [mean Hounsfield unit (HU), 1,148 ± 364]. There was also a significant correlation between tracer intensity by SUV and density of sclerotic lesions by HU both in ¹⁸F FCH PET–CT (r = −0.28, p < 0.006) and ¹⁸F fluoride PET–CT (r = −0.20, p < 0.05). The sensitivity, specificity and accuracy of PET–CT in the detection of bone metastases in prostate cancer was 81%, 93% and 86% for ¹⁸F fluoride, and 74% (p = 0.12), 99% (p = 0.01) and 85% for FCH, respectively. ¹⁸F FCH PET–CT led to a change in the management in two out of 38 patients due to the early detection of bone marrow metastases. ¹⁸F fluoride PET–CT identified more lesions in some patients when compared with ¹⁸F FCH PET–CT but did not change patient management. Conclusion  FCH PET–CT may be superior for the early detection (i.e. bone marrow involvement) of metastatic bone disease. In patients with FCH-negative suspicious sclerotic lesions, a second bone-seeking agent (e.g. ¹⁸F fluoride) is recommended. ¹⁸F fluoride PET–CT demonstrated a higher sensitivity than ¹⁸F FCH PET–CT, but the difference was not statistically significant. Furthermore, ¹⁸F fluoride PET could be also negative in highly dense sclerotic lesions, which presumably reflects the effect of treatment. It will be important to clarify in future studies whether these lesions are clinically relevant when compared with metabolically active bone metastases.     

Correlation of 4′-[methyl-<Superscript>11</Superscript>C]-thiothymidine uptake with Ki-67 immunohistochemistry and tumor grade in patients with newly diagnosed gliomas in comparison with <Superscript>11</Superscript>C-methionine uptake

Objective

A novel radiopharmaceutical, 4′-[methyl-¹¹C]thiothymidine (¹¹C-4DST), has been developed as an in vivo cell proliferation marker based on the DNA incorporation method. The purpose of this study was to evaluate ¹¹C-4DST uptake in patients with newly diagnosed glioma and to correlate the results with proliferative activity and tumor grade, in comparison with l-[methyl-¹¹C]-methionine (¹¹C-MET).

Methods

Investigations of ¹¹C-4DST and ¹¹C-MET PET/CT were performed retrospectively in 23 patients with newly diagnosed glioma. The maximum standardized uptake value (SUVmax) for tumor (T) and the mean SUV for normal contralateral hemisphere (N) were calculated, and the tumor-to-normal (T/N) ratio was determined. Metabolic tumor volume (MTV) was defined as the volume with a threshold of 40 % of the SUVmax. Proliferative activity as indicated by the Ki-67 index was estimated in tissue specimens.

Results

Of 23 gliomas examined, ¹¹C-4DST PET/CT and ¹¹C-MET PET/CT detected 20 and 22, respectively. Linear regression analysis between ¹¹C-4DST and ¹¹C-MET indicated a weak correlation for SUVmax (r = 0.54, P < 0.008), for T/N ratio (r = 0.56, P < 0.006), and for MTV (r = 0.60, P < 0.003). Linear regression analysis indicated a weak correlation between ¹¹C-4DST and Ki-67 index for SUVmax (r = 0.46, P < 0.03), for T/N ratio (r = 0.43, P < 0.05), and for MTV (r = 0.68, P < 0.001) and between ¹¹C-MET MTV and Ki-67 index (r = 0.43, P < 0.04). Using ¹¹C-4DST, there was a significant difference in SUVmax between grades II and IV (P < 0.03) and in MTV between grades II and IV (P < 0.009) and grades III and IV (P < 0.02). Using ¹¹C-MET, there was a significant difference in SUVmax (P < 0.009) and T/N ratio (P < 0.02) between grades II and IV and in MTV between grades II and IV (P < 0.03) and grades III and IV (P < 0.02).

Conclusion

¹¹C-4DST PET/CT is feasible for imaging of brain gliomas, as well as ¹¹C-MET PET/CT. Especially, it showed the highest correlation coefficient between ¹¹C-4DST MTV and Ki-67 index in newly diagnosed gliomas.

     

High treatment efficacy by dual targeting of Burkitt’s lymphoma xenografted mice with a <Superscript>177</Superscript>Lu-based CD22-specific radioimmunoconjugate and rituximab

Purpose

Dual-targeted therapy has been shown to be a promising treatment option in recurrent and/or refractory B-cell non-Hodgkin’s lymphoma (B-NHL). We generated radioimmunoconjugates (RICs) comprising either a novel humanized anti-CD22 monoclonal antibody, huRFB4, or rituximab, and the low-energy β-emitter ¹⁷⁷Lu. Both RICs were evaluated as single agents in a human Burkitt’s lymphoma xenograft mouse model. To increase the therapeutic efficacy of the anti-CD22 RIC, combination therapy with unlabelled anti-CD20 rituximab was explored.

Methods

The binding activity of CHX-A″-DTPA-conjugated antibodies to target cells was analysed by flow cytometry. To assess tumour targeting of ¹⁷⁷Lu-labelled antibodies, in vivo biodistribution experiments were performed. For radioimmunotherapy (RIT) studies, non-obese diabetic recombination activating gene-1 (NOD-Rag1 ^null ) interleukin-2 receptor common gamma chain (IL2rγ ^null ) null mice (NRG mice) were xenografted subcutaneously with Raji Burkitt’s lymphoma cells. ¹⁷⁷Lu-conjugated antibodies were administered at a single dose of 9.5 MBq per mouse. For dual-targeted therapy, rituximab was injected at weekly intervals (0.5 – 1.0 mg). Tumour accumulation of RICs was monitored by planar scintigraphy.

Results

Conjugation of CHX-A”-DTPA resulted in highly stable RICs with excellent antigen-binding properties. Biodistribution experiments revealed higher tumour uptake of the ¹⁷⁷Lu-labelled anti-CD22 IgG than of ¹⁷⁷Lu-labelled rituximab. Treatment with ¹⁷⁷Lu-conjugated huRFB4 resulted in increased tumour growth inhibition and significantly longer survival than treatment with ¹⁷⁷Lu-conjugated rituximab. The therapeutic efficacy of the anti-CD22 RIC could be markedly enhanced by combination with unlabelled rituximab.

Conclusion

These findings suggest that dual targeting with ¹⁷⁷Lu-based CD22-specific RIT in combination with rituximab is a promising new treatment option for refractory B-NHL.

     

Reproducibility of dopamine transporter density measured with<Superscript>123</Superscript>I-FPCIT SPECT in normal control and Parkinson’s disease patients

The objective of this study was to evaluate the reproducibility of 123I-FPCIT SPECT by using whole striatal region of interest (ROI) and subdivided ROI in normal controls (NC) and Parkinson's disease (PD) patients. METHODS: Ten NC and 6 PD received a SPECT scan for 6 hours postinjection of FPCIT. The distribution volume ratio (R(V)) and specific-nonspecific tissue activity ratio (RT) were measured as an outcome measure. The test/retest reproducibility of R(V) and R(T) was evaluated by calculating the test/retest difference, variability, and reliability. RESULTS: There were no significant test/retest differences for any regions in either the NC or PD. The test/retest variability/reliability of Rv was 5.53+/-4.12%/0.89 in NC, 4.50+/-5.31%/0.99 in PD with whole striatal ROI, 4.29+/-0.78%/ 0.94+/-0.03 in NC, and 6.87+/-1.23 %/0.98+/-0.01 in PD with subdivided ROI. The test/retest variability/reliability of RT was 11.1+/-10.4%/0.59 in NC, 7.84+/-8.94%/0.95 in PD with whole striatal ROI, 11.9+/-1.22%/0.65+/-0.06 in NC, and 12.2+/-4.00%/0.95+/-0.03 in PD with subdivided ROI. CONCLUSION: R(V) is highly reproducible and reliable compared with RT in both NC and PD as an outcome measure.     

Do androgens control the uptake of <Superscript>18</Superscript>F-FDG, <Superscript>11</Superscript>C-choline and <Superscript>11</Superscript>C-acetate in human prostate cancer cell lines?

Purpose  

The aim of this study was to evaluate the impact of androgen ablation therapy in different prostate cancer (PCa) cell lines—reflecting different stages of the disease—on ¹⁸F-fluorodeoxyglucose (FDG), ¹¹C-choline and ¹¹C-acetate uptake.     

Automated striatal uptake analysis of <Superscript>18</Superscript>F-FDOPA PET images applied to Parkinson’s disease patients

Objective  

6-[¹⁸F]Fluoro-l-DOPA (FDOPA) is a radiopharmaceutical valuable for assessing the presynaptic dopaminergic function when used with positron emission tomography (PET). More specifically, the striatal-to-occipital ratio (SOR) of FDOPA uptake images has been extensively used as a quantitative parameter in these PET studies. Our aim was to develop an easy, automated method capable of performing objective analysis of SOR in FDOPA PET images of Parkinson’s disease (PD) patients.     

Early [<Superscript>18</Superscript>F]florbetaben and [<Superscript>11</Superscript>C]PiB PET images are a surrogate biomarker of neuronal injury in Alzheimer’s disease

Purpose

[¹⁸F]FDG is a commonly used neuronal injury biomarker for early and differential diagnosis of dementia. Typically, the blood supply to the brain is closely coupled to glucose consumption. Early uptake of the Aβ tracer [¹¹C]PiB on PET images is mainly determined by cerebral blood flow and shows a high correlation with [¹⁸F]FDG uptake. Uptake data for ¹⁸F-labelled Aβ PET tracers are, however, scarce. We investigated the value of early PET images using the novel Aβ tracer [¹⁸F]FBB in the diagnosis of Alzhimers disease (AD).

Methods

This retrospective analysis included 22 patients with MCI or dementia who underwent dual time-point PET imaging with either [¹¹C]PiB (11 patients) or [¹⁸F]FBB (11 patients) in routine clinical practice. Images were acquired 1 – 9 min after administration of both tracers and 40 – 70 min and 90 – 110 min after administration of [¹¹C]PiB and [¹⁸F]FBB, respectively. The patients also underwent [¹⁸F]FDG brain PET imaging. PET data were analysed visually and semiquantitatively. Associations between early Aβ tracer uptake and dementia as well as brain atrophy were investigated.

Results

Regional visual scores of early Aβ tracer and [¹⁸F]FDG PET images were significantly correlated (Spearman’s ρ?=?0.780, P?<?0.001). Global brain visual analysis revealed identical results between early Aβ tracer and [¹⁸F]FDG PET images. In a VOI-based analysis, the early Aβ tracer data correlated significantly with the [¹⁸F]FDG data (r?=?0.779, P?<?0.001), but there were no differences between [¹⁸F]FBB and [¹¹C]PiB. Cortical SUVRs in regions typically affected in AD on early Aβ tracer and [¹⁸F]FDG PET images were correlated with MMSE scores (ρ?=?0.458, P?=?0.032, and ρ?=?0.456, P?=?0.033, respectively). A voxel-wise group-based search for areas with relatively higher tracer uptake on early Aβ tracer PET images compared with [¹⁸F]FDG PET images revealed a small cluster in the midbrain/pons; no significant clusters were found for the opposite comparison.

Conclusion

Early [¹⁸F]FBB and [¹¹C]PiB PET brain images are similar to [¹⁸F]FDG PET images in AD patients, and these tracers could potentially be used as biomarkers in place of [¹⁸F]FDG. Thus, Aβ tracer PET imaging has the potential to provide biomarker information on AD pathology and neuronal injury. The potential of this approach for supporting the diagnosis of AD needs to be confirmed in prospective studies in larger cohorts.