PMR is a common inflammatory rheumatic disease. Although its clinical characteristics are fully recognized, no specific test for its diagnosis has been established to date. Several studies have ...described a wide variety of diseases that present with polymyalgic symptoms. A .sup.18 FDG-PET/CT scan could help to deal with these differential diagnoses. The goal of our study is to describe the findings of the .sup.18 FDG-PET/CT scan in a cohort of PMR patients and to detail how the .sup.18 FDG-PET/CT scan improves accuracy when diagnosing other underlying conditions. This cross-sectional study enrolled patients with a diagnosis of PMR who underwent to a .sup.18 FDG-PET/CT scan to rule out other diagnosis. The .sup.18 FDG-PET/CT scan was performed either following clinical criteria at the onset of clinical symptoms or when the patient became PMR steroid resistant. Patients' demographic, clinical and analytical data at the moment of the .sup.18 FDG-PET/CT scan were recorded. The final diagnosis was confirmed according to clinical judgement. A total of 103 patients with PMR were included. In 49.51% of patients, the .sup.18 FDG-PET/CT scan was ordered to study resistance to steroid therapy. The final diagnoses of patients were PMR in 70.9% patients, large vessel vasculitis in 15.5%, neoplasms 4.8% and another diagnosis in the rest. The .sup.18 FDG-PET/CT scan is a very useful technique for the study of Polymyalgia Rheumatica, not only to help in the diagnostic process, but also due to its role in the identification of a variety of PMR-like patrons.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Objective
The purpose of this study was to compare image quality and lesion detection capability between a digital and an analog PET/CT system in oncological patients.
Materials and methods
One ...hundred oncological patients (62 men, 38 women; mean age of 65 ± 12 years) were prospectively included from January–June 2018. All patients, who accepted to be scanned by two systems, consecutively underwent a single day, dual imaging protocol (digital and analog PET/CT). Three nuclear medicine physicians evaluated image quality using a 4-point scale (−1, poor; 0, fair; 1, good; 2, excellent) and detection capability by counting the number of lesions with increased radiotracer uptake. Differences were considered significant for a
p
value <0.05.
Results
Improved image quality in the digital over the analog system was observed in 54% of the patients (
p
= 0.05, 95% CI, 44.2–63.5). The percentage of interrater concordance in lesion detection capability between the digital and analog systems was 97%, with an interrater measure agreement of κ = 0.901 (
p
< 0.0001). Although there was no significant difference in the total number of lesions detected by the two systems (digital: 5.03 ± 10.6 vs. analog: 4.53 ± 10.29;
p
= 0.7), the digital system detected more lesions in 22 of 83 of PET+ patients (26.5%) (
p
= 0.05, 95% CI, 17.9–36.7). In these 22 patients, all lesions detected by the digital PET/CT (and not by the analog PET/CT) were < 10 mm.
Conclusion
Digital PET/CT offers improved image quality and lesion detection capability over the analog PET/CT in oncological patients, and even better for sub-centimeter lesions.
Purpose
The purpose of this study was to assess whether digital photon counting technology in digital PET/CT influences the quantification of SUVmax in target lesions and regions of reference ...compared to analog PET/CT before an interchangeable use of either system in follow up studies.
Methods
From January to June of 2018, 100 oncological patients underwent successive PET/CT imaging with digital and analog systems in the same day. Fifty-eight patients underwent analog imaging first and digital imaging thereafter, and 42 patients the other way round. SUVmax was measured in reference regions (liver and mediastinal blood pool) and in the most metabolically active target lesion in each patient. According to the sequence order of PET/CT acquisition, two groups of SUVmax values were obtained, i.e. group 1: analog PET/CT performed first; group 2: digital PET/CT performed first.
Results
Mean SUVmax in the total sample (regardless of the order of PET/CT acquisition) in the target lesions with the analog PET/CT was 8.14 ± 6.39 and the digital 9.97 ± 6.14 (
P
= 0.000). Total mean SUVmax in the liver with the analog was 4.39 ± 2.59 and the digital 4.46 ± 3.18 (
P
= 0.477). Total mean SUVmax in the mediastinal blood pool with the analog was 2.30 ± 0.67 and the digital 2.54 ± 0.74 (
P
= 0.000).
Group 1: mean SUVmax in the target lesions with the analog system was 6.64 ± 4.71 and the digital 9.48 ± 5.60 (
P
= 0.000). Mean liver SUVmax with the analog was 4.70 ± 2.90 and the digital 4.80 ± 3.72 (
P
= 0.088). Mediastinal blood pool SUVmax with the analog was 2.33 ± 0.66 and the digital 2.45 ± 0.73 (
P
= 0.041).
Group 2: mean SUVmax in target lesions with the digital system was 10.63 ± 6.88 and the analog 10.16 ± 7.76 (
P
= 0.046). Mean liver SUVmax with the digital was 3.99 ± 2.20 and the analog 3.96 ± 2.04 (
P
= 0.218). Mediastinal blood pool SUVmax with the digital was 2.66 ± 0.75 and the analog 2.27 ± 0.68 (
P
= 0.000).
No significant differences between both time delays were found.
Conclusions
Improved photon counting technology in the digital PET/CT, and the effect of delayed increased uptake and retention significantly increases SUVmax values. This has to be taken into account before interchangeable use of either system in follow up studies.
Positron emission tomography (PET) is a functional imaging technique introduced in 1970s. Over the years, PET was used alone but is in 2000 when the first hybrid PET/CT device was clinically ...introduced. Since then, PET has continuously been marked by technological developments, being the most recent one the introduction of silicon photomultipliers (SiPMs) as an alternative to standard photomultiplier tubes used in analog PET/CT systems. SiPMs, the basis for the so called digital PET/CT systems, are smaller than standard photomultiplier tubes (enabling higher spatial resolution) and provide up to 100% coverage of the crystal area, as well as high sensitivity, low noise, and fast timing resolution. SiPMs in combination with optimized acquisition and reconstruction parameters improve the localization of the annihilation events, provide high definition PET images, and offer higher sensitivity and higher diagnostic performance. This article summarizes the evidence about the superior performance of the state of the art digital PET and highlights its potential clinical implications. Digital PET opens new perspectives in the quantification and characterization of small lesions, which are mostly undetectable using analog PET systems, potentially changing patient management and improving outcomes in oncological and non-oncological diseases. Moreover, digital PET offers the possibility to reduce radiation dose and scan times which may facilitate the implementation of PET to address unmet clinical needs.
Striatal dopamine transporter (DAT) uptake assessment through I123-Ioflupane Single-Pphoton Emission Computed Tomography (SPECT) provides valuable information about the dopaminergic denervation ...occurring in Parkinson's disease (PD). However, little is known about the clinical or biological relevance of extrastriatal DAT uptake in PD. Here, from the Parkinson's Progression Markers Initiative, we studied 623 participants (431 PD and 192 healthy controls) with available SPECT data. Even though striatal denervation was undoubtedly the imaging hallmark of PD, extrastriatal DAT uptake was also reduced in patients with PD. Topographically, widespread frontal but also temporal and posterior cortical regions showed lower DAT uptake in PD patients with respect to healthy controls. Importantly, a longitudinal voxelwise analysis confirmed an active one-year loss of extrastriatal DAT uptake within the PD group. Extrastriatal DAT uptake also correlated with the severity of motor symptoms, cognitive performance, and cerebrospinal fluid α-synuclein levels. In addition, we found an association between the Catechol-O-methyltransferase val158met genotype and extrastriatal DAT uptake. These results highlight the clinical and biological relevance of extrastriatal SPECT-DAT uptake in PD.
•Little is known about the significance of extrastriatal SPECT-DAT alterations in PD.•Cortical reductions in SPECT-DAT uptake in de novo PD patients are described.•These alterations correlated with the patient's motor and cognitive status.•Extrastriatal DAT uptake was also associated with CSF α-syn levels and COMT genotype.•These findings motivate the study of extrastriatal SPECT-DAT in PD.
Purpose
To assess metabolic changes in cerebral
18
F-FDG PET/CT in premanifest and manifest Huntington’s disease (HD) subjects compared to a control group and to correlate
18
F-FDG uptake patterns ...with different disease stages.
Materials and methods
Thirty-three gene-expanded carriers (Eight males; mean age: 43 y/o; CAG > 39) were prospectively included. Based on the Unified Huntington’s Disease Rating Scale Total Motor Score and the Total Functional Capacity, subjects were classified as premanifest (preHD = 15) and manifest (mHD = 18). Estimated time disease-onset was calculated using the Langbehn formula, which allowed classifying preHD as far-to (preHD-A) and close-to (PreHD-B) disease-onset. Eighteen properly matched participants were included as a control group (CG). All subjects underwent brain
18
F-FDG PET/CT and MRI.
18
F-FDG PET/CT were initially assessed by two nuclear medicine physicians identifying qualitative metabolic changes in the striatum. Quantitative analysis was performed using SPM8 with gray matter atrophy correction using the BPM toolbox.
Results
Visual analysis showed a marked striatal hypometabolism in mHD. A normal striatal distribution of
18
F-FDG uptake was observed for most of the preHD subjects. Quantitative analysis showed a significant striatal hypometabolism in mHD subjects compared to CG (
p
< 0.001 uncorrected,
k
= 50 voxels). In both preHD groups we observed a significant striatal hypometabolism with respect to CG (
p
< 0.001 uncorrected,
k
= 50 voxels). In mHD subjects we observed a significant striatal hypometabolism with respect to both preHD groups (
p
< 0.001 uncorrected,
k
= 50 voxels).
Conclusion
18
F-FDG PET/CT might be a helpful tool to identify patterns of glucose metabolism in the striatum across the stages of HD and might be relevant in assessing the clinical status of gene-expanded HD carriers due to the fact that dysfunctional glucose metabolism begins at early preHD stages of the disease.
18
F-FDG PET/CT appears as a promising method to monitor the response to disease-modifying therapies even if applied in premanifest subjects.
Objective
To compare detectability of hyperfunctioning parathyroid tissue (HPT) by digital and analog 18F-fluorocholine PET/CT in patients with primary hyperparathyroidism and negative/inconclusive ...99mTc-MIBI scintigraphy-SPECT/CT.
Materials and methods
Thirty-three patients with primary hyperparathyroidism and negative/inconclusive 99mTc-MIBI scintigraphy-SPECT/CT were prospectively included. All patients accepted to be scanned by digital and analog PET/CT in the same imaging session after a single injection of 18F-fluorocholine. Three nuclear medicine physicians evaluated the digital and analog PET/CT datasets to assess the detection rate of HPT. Maximum standard uptake values (SUVmax) of HPT and locoregional lymph nodes were measured in both systems.
Results
HPT was detected in 30/33 patients by the digital system, whereas it was detected in 22/33 patients by the analog system (
p
< 0.01). Moreover, in 21 of these 33 patients, both systems detected one focal 18F-fluorocholine uptake, and in one patient the digital system detected two foci. Histopathology demonstrated HPT in 32 patients and it was inconclusive in one patient. The digital PET/CT detected HPT in 29 of the 32 patients, and the analog system in 22 of the 32 (
p
< 0.01). All HPT suspected lesions resected and detected only by the digital system (
n
= 8) were < 10 mm (7.5 ± 1.3 mm), while those detected by both systems (
n
= 22) were > 10 mm (13 ± 3.8 mm). SUVmax of HPT lesions was significantly higher than SUVmax of locoregional lymph node independently of the PET/CT system used (4.5 ± 1.9 vs. 2.9 ± 1.3,
p
< 0.0001).
Conclusions
Digital PET/CT offers superior performance over analog system in patients with suspected HPT and previous negative/inconclusive imaging examinations, particularly in sub-centimeter lesions. SUVmax can help in the differentiation between HTP and locoregional lymph nodes.
PDF
