We aimed to investigate the interaction between β -amyloid (Aβ) accumulation and cerebral glucose metabolism, cerebral perfusion, and cerebral structural changes in the Alzheimer's disease (AD) ...clinical continuum.
Utility of positron emission tomography (PET) / magnetic resonance imaging (MRI) hybrid imaging for diagnostic categorization of the AD clinical continuum including subjective cognitive decline (SCD), amnestic mild cognitive impairment (aMCI) and Alzheimer's disease dementia (ADD) has not been fully crystallized.
To evaluate the interaction between Aβ accumulation and cerebral glucose metabolism, cerebral perfusion, and cerebral structural changes such as cortex thickness or cerebral white matter disease burden and to detect the discriminative yields of these imaging modalities in the AD clinical continuum.
Fifty patients (20 women and 30 men; median age: 64 years) with clinical SCD (n=11), aMCI (n=17) and ADD (n=22) underwent PET/MRI with
F-fluoro-D-glucose (FDG) and
F- Flutemetamol in addition to cerebral blood flow (CBF) and quantitative structural imaging along with detailed cognitive assessment.
High Aβ deposition (increased temporal
F-Flutemetamol standardized uptake value ratio (SUVr) and centiloid score), low glucose metabolism (decreased temporal lobe and posterior cingulate
F-FDG SUVr), low parietal CBF and right hemispheric cortical thickness were independent predictors of low cognitive test performance.
Integrated use of structural, metabolic, molecular (Aβ) and perfusion (CBF) parameters contribute to the discrimination of SCD, aMCI, and ADD.
Autologous stem cell transplantation (ASCT) remains the mainstay of the treatment in newly diagnosed transplant-eligible multiple myeloma (MM) patients. This retrospective study was performed to ...investigate the potential prognostic markers which may modify transplant course in a total of 256 ASCT recipients median age: 58 (30–74) years; male/female: 138/118, including pretransplant (PET
0
) and day + 60 (PET
2
) PET/CT assessments and comparative analysis of melphalan (Mel) dose. Better responses with significantly higher complete response/very good partial response rates were achieved in patients who proceeded to transplant within 301 days from diagnosis (
p
< 0.001). Patients who had received < 1.5 lines of treatment prior to transplant had significantly higher probability of overall survival (OS) (
p
= 0.004) and progression-free survival (PFS) (
p
< 0.001). The probability of OS was significantly higher in patients with low Eastern Cooperative Oncology Group (ECOG) performance score (PS = 0–1) (
p
= 0.003) and HCT-Comorbidity Index (HCT-CI = 0) (
p
= 0.011). The number of involved areas (
p
= 0.028) and maximum standardized uptake value (SUV
max
) (
p
= 0.021) in PET
0
represented significant impact on OS. The probabilities of OS (
p
< 0.001) and PFS (
p
= 0.01) were significantly better with Mel200 mg/m
2
conditioning compared to Mel140 mg/m
2
. Conditioning with Mel200 mg/m
2
, early and upfront ASCT and low pretransplant treatment burden were found to be significantly associated with ASCT outcome in MM patients. Despite its predictor impact on survival and prognosis, further studies are warranted to standardize PET/CT-based response assessments before being used as a guide for treatment decisions in clinical practice.
Objective To examine the reflux nephropathy rate and severity as well as the hypertension rate in pediatric patients with vesicoureteral reflux (VUR). Methods The study included 240 patients with ...VUR. Renal scarring (RS) was demonstrated by renal parenchymal examination using technetium-99m–labeled dimercaptosuccinic acid (99m Tc-DMSA) scintigraphy. Office measurements of arterial blood pressure and ambulatory blood pressure monitoring (ABPM) of VUR patients were done during the follow-up period. Results Follow-up was a mean duration of 24 months. Rates of RS and hypertension increased parallel to increases in the degree of VUR. A gradual elevation in hypertension rates was evident during the follow-up period. All patients with hypertension had RS. Severe RS in 56 patients was associated with increasing blood pressure readings by 24-hour ABPM or office measurements in 19 patients (33.9%). ABPM measurements enabled us to detect additional patients compared with office measurements alone. Conclusion Hypertension is a serious complication in children with reflux nephropathy and is associated with the severity of RS and VUR grade. ABPM seems to be superior over office measurements of blood pressure in identifying patients with hypertension.
Advances in the molecular biology, pathology and genetics of Alzheimer's disease (AD) and other degenerative dementias have led to the development of biomarkers specific to these diseases and ...radiotracers that are used in nuclear medicine. Imaging and non-imaging markers have enabled very early recognition of these diseases and have caused significant changes in their definitions. Amyloid positron emission tomography (PET) and tau PET, which are molecular imaging methods, F18fluorodeoxyglucose (FDG) PET showing the glucose metabolism pattern in the brain, dopamine transporter single photon emission computerized tomography (SPECT) that marks dopaminergic terminals are valuable tools for early recognition and differentiation of AD and its atypical variants, frontotemporal dementias and dementia with Lewy bodies. These imaging methods, which have different advantages over each other, have different indications for use and sometimes provide complementary information. In addition, research on radiotracers targeting neuroinflammation, astrocytes, synaptic density, and cholinergic terminals is ongoing. In this review, routinely used and newly developed nuclear imaging methods in AD and other neurodegenerative dementias, the agents used and their diagnostic features will be presented together with case examples.
We aimed to explore the utility and additional clinical contribution of brain fluorodeoxyglucose (FDG) PET imaging for the assessment of children with possible autoimmune encephalitis in comparison ...to brain MRI.
We conducted a retrospective analysis of six pediatric patients (all seronegative) between 2014 and 2019 with the initial diagnosis of possible autoimmune encephalitis who had brain FDG PET/CT or PET/MRI and brain MRI during the diagnostic period. Diagnosis of possible autoimmune encephalitis was based on clinical consensus criteria defined by Graus et al. Brain FDG PET images were visually evaluated. Semiquantitative evaluation was also performed by using the statistical parametric mapping (SPM) method.
Cerebrospinal fluid pleiocytosis and electroencephalography abnormality were present in all patients. Mean duration between the onset of symptoms and brain FDG PET imaging was 33 ± 16 days (range: 18-62 days). There were a total of eight brain FDG PET scans (six of PET/MRI and two of PET/CT). In two patients, FDG PET imaging was performed at diagnosis and follow-up. Initial FDG PET and SPM analysis findings were abnormal in all patients (100%), with four demonstrating only hypometabolism. Only a hypermetabolic pattern was seen in one patient, and mixed the hypohypermetabolic pattern was seen in one patient. All patients had metabolic abnormalities in temporal lobes. Additionally, visual and semiquantitative FDG PET findings revealed hypometabolism in extratemporal regions. Brain MRI was abnormal in two patients (33.3%) who had also FDG hypermetabolism in mesial temporal lobes.
Our findings support the usage of fluorine-18-FDG PET/computed tomography (CT)/MRI with quantitative analysis early in the diagnostic work-up of possible autoimmune encephalitis, particularly in those with normal or nonspecific MRI findings. However, it remains a purpose of further studies, if and to what extent FDG PET/CT or integrated FDG PET/MRI with quantitative analysis can improve the diagnostic workup of children with possible autoimmune encephalitis.
: The aim of our study was to evaluate the effect of reduced injected tracer activities on the quantitative image metrics and the visual image quality in whole-body 18F-FDG PET/MRI with TOF ...capability in pediatric oncology.
Seventy-seven PET/MRI examinations of 54 patients were analyzed (standard injected activity: 1.9 MBq/kg, standard PET scan duration: 5 min per bed position). Lower activity PET images (1.2 MBq/kg and 0.9 MBq/kg) were retrospectively simulated from the originally acquired list-mode data sets. Quantitative parameters were assessed by measuring the SUV metrics, signal-to-noise ratio (SNR), contrast-to-noise ratios (CNR), and textural features in each PET data set. PET images were also evaluated visually for image quality by using a scoring system.
SNRs were found as significantly different among PET data sets (p < 0.001) and showed increasing image noise with decreasing activities. CNR values did not show significant differences among PET data sets. The mean relative percentage changes in SUV metrics were found to be lower in 1.2 MBq/kg data set compared to 0.9 MBq/kg data set. Lesion SUVmax, SUVmean, SULpeak, and textural features were significantly different in 0.9 MBq/kg data set compared to the original data set (p < 0.05 for all). However, SUV metrics and textural features did not show a significant difference between the original and 1.2 MBq/kg data sets. While, the mean visual scores in 0.9 MBq/kg data set were significantly different compared to the original data set (p < 0.001), there was no significant difference between the original and 1.2 MBq/kg data sets in terms of general image quality and image sharpness.
Our analyses showed that the reduction of injected activity to 1.2 MBq/kg may be feasible in pediatric oncological PET/ MRI, with a smaller relative percentage change in quantitative parameters and with similar image quality to the original data set.
ObjectivesThe aim of this study was to evaluate the relationship between the types of distant metastatic spread, histopathological features, and imaging features of primary tumor on positron emission ...tomography/magnetic resonance imaging (PET/MRI) for primary staging in newly diagnosed breast invasive ductal carcinoma (IDC) patients.MethodsData from 289 female patients were retrospectively evaluated. Maximum standardized uptake value, metabolic tumor volume (MTV), total lesion glycolysis (TLG), and minimum apparent diffusion coefficient (ADCmin) values of primary tumors were obtained from PET/MRI. The patients were grouped as non-metastatic, oligometastatic (1-5 metastatic lesions) and multimetastatic (>5 metastatic lesions) disease according to the number of distant metastases, and divided into two groups as isolated bone metastasis (IBM) and mixed/soft tissue metastasis (M-SM) groups according to the sites of metastatic spread.ResultsMetabolic parameters had higher values and ADCmin had lower values in the multimetastatic and oligometastatic groups than in the non-metastatic group. MTV was the only parameter that showed significant difference between the multimetastatic and oligometastatic groups. MTV and TLG were significantly higher in the M-SM group than in the IBM group. 18F-fluorodeoxyglucose PET parameters had significantly higher values in grade 3, hormone receptor negative, human epidermal growth factor receptor 2 positive, triple negative, and highly proliferative (Ki-67 ≥14%) tumors. The prediction models that included imaging parameters to predict the presence of distant metastasis had higher discriminatory powers than the prediction models that included only histopathological parameters.ConclusionPrimary tumors with higher metabolic-glycolytic activity and higher cellularity were more aggressive and had higher metastatic potential in breast IDC. Compared with histopathological parameters alone, the combination of imaging parameters and histopathological features of primary tumors may help to better understand tumor biology and behavior.
Objective: Few data are available on the clinical significance of 18-fluorodeoxyglucose positron emission tomography (FDG-PET/CT) results in patients with leukemia. We investigated the utility of ...FDG-PET/CT at the time of relapsed/refractory disease in pediatric patients with leukemia. Methods: Medical records of 28 children with suspected leukemia progression or recurrence during/after chemotherapy or allogeneic stem cell transplantation (allo-SCT) were retrospectively reviewed to determine the utility of FDG-PET/CT. Results: Twenty-two of the 28 patients have documented abnormal imaging findings during clinical follow-up, while six had were interpreted as not demonstrating signal consistent with active leukemia. Of the 22 patients with abnormal FDG-PET/CT studies 14 were found to have FDG-PET/CT reported as consistent with active leukemia and increased leukemia blasts on bone marrow biopsy. Regarding the eight patients without positive FDG-PET/CT and proven leukemia relapse, four had discordant findings on FDG-PET/CT and biopsy, and four had FDG-PET/CT reported as infection. Mean maximum standardized uptake values (SUVmax) were significantly higher among patients whose FDG-PET/CT findings were positive for leukemia as opposed to infectious disease (p < .05). Mean SUVmax was also significantly higher among patients with multifocal lesions on FDG-PET/CT than among those with diffuse lesions (p < .05). Conclusions: The findings suggest that FDG-PET/CT may be a complementary imaging modality that could be combined with bone marrow examination to improve detection of subtle leukemic infiltration in children with suspected leukemia progression or recurrence after chemotherapy or allo-SCT.
Our aim was to present our experiences related to performing neck surgery using the guided intraoperative scintigraphic tumor targeting (GOSTT) procedure for patients who had locally recurrent or ...persistent differentiated thyroid cancer (DTC) and who had undergone previous thyroid surgery.
We retrospectively evaluated 11 patients who had locally recurrent or persistent DTC, who had undergone previous surgery, and for whom reoperation was planned for metastatic cervical lymph nodes (LNs). We performed the neck surgery using the GOSTT procedure on all patients and at a single academic institution.
The 11 patients had a total of 26 LNs, as marked with a radiotracer, and those LNs' mean size was 14.7 ± 8.2 mm (range: 5-34 mm). Histopathological examinations revealed DTC metastasis in all 26 of the preoperatively marked LNs. Of the 11 patients, only one needed a reoperation in the neck; she had another successful surgery (also using the GOSTT procedure). In the evaluation of the patients' final status, all were disease-free in their necks. There also were no GOSTT-associated postoperative complications.
The GOSTT procedure is a useful, successful, inexpensive, and comfortable procedure for marking and mapping metastatic LNs, especially in DTC patients who have undergone previous surgery.
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