Background and Aims:
The aim of this study was to compare the accuracy and clinical impact of hybrid positron emission tomography PET/magnetic resonance-enterography MR-E and PET/computed ...tomography-enterography CT-E in patients with Crohn’s disease CD.
Methods:
A total of 35 patients with symptomatic small-bowel CD who were scheduled to undergo operation were evaluated before operation by same-day PET/CT-E and PET/MR-E. PET/MR-E was also compared with MR-E alone. Imaging accuracy for detecting pathological sites and discriminating between fibrotic and inflammatory strictures was assessed. Treatment was adjusted according to imaging findings and change in medical/surgical strategy was also evaluated.
Results:
PET/CT-E, PET/MR-E, and MR-E were equally accurate in detecting CD sites. PET/MR-E was more accurate in assessing extra-luminal disease p = 0.002, which was associated with higher need for stoma p = 0.022 and distant localisation p = 0.002. When the latter was observed, laparoscopy was started with hand-assisted device, reducing operative time p = 0.022. PET/MR-E was also more accurate in detecting a fibrotic component compared with PET/CT-E p = 0.043 and with MR-E p = 0.024. Fibrosis was more frequently classified as inflammation with MR-E compared with PET/MR-E p = 0.019. Out of 8 patients with predominantly inflammatory CD who received medical treatment, 6 75% remained surgery free. Overall, 29 patients received surgery. At median follow-up of 9 6–22 months, no recurrences occurred in either the medical or the surgical group.
Conclusions:
Preoperative PET/MR-E imaging is highly accurate for assessing CD lesions before operation and contributed to clinical management of patients with small-bowel CD more often than PET/CT-E.
A normal stress myocardial perfusion single-photon emission computed tomography (MPS) is associated with a good clinical outcome. New iterative algorithms, such as wide beam reconstruction (WBR), ...which improve image interpretation with half-dose or half-time acquisition, have been proposed for cardiac MPS. The aim of this study was to assess the long-term predictive value of a low-dose normal stress-only MPS with WBR using conventional Anger camera in patients with known or suspected coronary artery disease (CAD).
A total of 2106 patients with known or suspected CAD and normal perfusion at half-dose stress-only MPS protocol were followed for a mean of 6.6 ± 2.7 years. MPS data were reconstructed with WBR iterative algorithm. End-point events were cardiac death or nonfatal myocardial infarction. Noncardiac death was considered the competing event. During follow-up, 149 cardiac events occurred with an annualized event rate of 1.2%. Independent predictors of cardiac events at Cox analysis were age, male gender, diabetes mellitus, previous myocardial infarction and the need for pharmacologic stress testing. At Fine-Gray analysis the cumulative incidence of cardiac events progressively increases with age and in the presence of diabetes for any combination of gender and stress type. Survival tree analysis confirmed that long-term prognosis considerably varies according of risk factors profile.
Low-dose normal stress-only WBR MPS has a reliable long-term prognostic value in patients with suspected or known CAD. This finding supports the introduction of such a method into clinical practice with a consistent dose optimization in the interest of patients and exposed staff.
Background
The lack of visualization of the spinal cord hinders the evaluation of
18
FFluoro-deoxy-glucose (FDG) uptake of the spinal cord in PET/CT. By exploiting the capability of MRI to precisely ...outline the spinal cord, we performed a retrospective study aimed to define normal pattern of spinal cord
18
FFDG uptake in PET/MRI.
Methods
Forty-one patients with lymphoma without clinical or MRI signs of spinal cord or bone marrow involvement underwent simultaneous PET and MRI acquisition using Siemens Biograph mMR after injection of 3.5 MBq/kg body weight of
18
FFDG for staging purposes. Using a custom-made software, we placed ROIs of 3 and 9 mm in diameter in the spinal cord, lumbar CSF, and vertebral marrow that were identified on MRI at 5 levels (C2, C5, T6, T12, and L3). The SUVmax, SUVmean, and the SUVmax and SUVmean normalized (NSUVmax and NSUVmean) to the liver were measured. For comparison, the same ROIs were placed in PET-CT images obtained immediately before the PET-MRI acquisition following the same tracer injection.
Results
On PET/MRI using the 3 mm ROI, the following average (all level excluding L3) spinal cord median (1st and 3rd quartile) values were measured: SUVmean, 1.68 (1.39 and 1.83); SUVmax, 1.92 (1.60 and 2.14); NSUVmean, 1.18 (0.93 and 1.36); and NSUVmax, 1.27 (1.01 and 1.33). Using the 9 mm ROI, the corresponding values were SUVmean, 1.41 (1.25–1.55); SUVmax, 2.41 (2.08 and 2.61); NSUVmean, 0.93 (0.79 and 1.04); and NSUVmax, 1.28 (1.02 and 1.39). Using the 3 mm ROI, the highest values of PET-MRI SUVmax, SUVmean, NSUVmax, and NSUVmean were consistently observed at C5 and the lowest at T6. Using a 9 mm ROI, the highest values were consistently observed at C5 and the lowest at T12 or T6. The spinal cord
18
FFDG-uptake values correlated with the bone marrow uptake at the same level, especially in case of NSUVmax. Comparison with PET-CT data revealed that the average SUVmax and SUVmean of the spinal cord were similar in PET-MRI and PET-CT. However, the average NSUVmax and NSUVmean of the spinal cord were higher (range 21–47%) in PET-MRI than in PET-CT.
Conclusions
Using a whole-body protocol, we defined the maximum and mean
18
FFDG uptake of the normal spinal cord in PET/MRI. While the observed values show the expected longitudinal distribution, they appear to be higher than those measured in PET/CT. Normalization of the SUVmax and SUVmean of the spinal cord to the liver radiotracer uptake could help in multi-institutional comparisons and studies.
The present review provides a description of recent advances in the field of functional imaging that takes advantage of the functional characteristics of thyroid neoplastic cells (such as radioiodine ...uptake and FDG uptake) and theragnostic approach of differentiated thyroid cancer (DTC). Physical and biological characteristics of available radiopharmaceuticals and their use with state-of-the-art technologies for diagnosis, treatment, and follow-up of DTC patients are depicted. Radioactive iodine is used mostly with a therapeutic intent, while PET/CT with 18F-FDG emerges as a useful tool in the diagnostic management and complements the use of radioactive iodine. Beyond 18F-FDG PET/CT, other tracers including 124I, 18F-TFB and 68Ga-PSMA, and new methods such as PET/MR, might offer new opportunities in selecting patients with DTC for specific imaging modalities or treatments.
Aims
18
F-FDG PET/CT is the most accurate imaging modality in differentiated thyroid cancer (DTC) patients with either an aggressive histology, an absence of radioiodine uptake in neoplastic foci, or ...in the absence of imaging abnormalities in patients with an elevated serum thyroglobulin (Tg) level that progresses with time. We evaluated the diagnostic performance of FDG PET/MR in comparison with that of PET/CT.
Methods and results
Following the injection of a single
18
F-FDG activity, PET/MR and PET/CT were sequentially performed in 40 consecutive patients with DTC previously treated with total thyroidectomy and radioiodine ablation. All patients were then followed up for at least 6 months. PET/MR was positive in 11 patients and PET/CT in 10. PET/MR detected 33 tumor foci and PET/CT 30. During the follow-up of the 12 patients with negative initial PET studies and with a detectable serum Tg, only one patient had a neck recurrence and the administration of an empiric high activity of
131
I in the other 11 patients did not reveal any tumor focus. In the 17 patients with an initial serum Tg level < 2 ng/mL, no recurrence occurred.
Conclusion
This study confirms the high diagnostic accuracy of FDG PET studies in DTC patients with elevated serum Tg levels and shows that PET/MR brings similar information as compared to PET/CT imaging.
Background
Clinical markers of cognitive decline in Parkinson's disease (PD) encompass several mental non-motor symptoms such as hallucinations, apathy, anxiety, and depression. Furthermore, freezing ...of gait (FOG) and specific gait alterations have been associated with cognitive dysfunction in PD. Finally, although low cerebrospinal fluid levels of amyloid-β42 have been found to predict cognitive decline in PD, hitherto PET imaging of amyloid-β (Aβ) failed to consistently demonstrate the association between Aβ plaques deposition and mild cognitive impairment in PD (PD-MCI).
Aim
Finding significant features associated with PD-MCI through a machine learning approach.
Patients and methods
Patients were assessed with an extensive clinical and neuropsychological examination. Clinical evaluation included the assessment of mental non-motor symptoms and FOG using the specific items of the MDS-UPDRS I and II. Based on the neuropsychological examination, patients were classified as subjects without and with MCI (noPD-MCI, PD-MCI). All patients were evaluated using a motion analysis system. A subgroup of PD patients also underwent amyloid PET imaging. PD-MCI and noPD-MCI subjects were compared with a univariate statistical analysis on demographic data, clinical features, gait analysis variables, and amyloid PET data. Then, machine learning analysis was performed two times: Model 1 was implemented with age, clinical variables (hallucinations/psychosis, depression, anxiety, apathy, sleep problems, FOG), and gait features, while Model 2, including only the subgroup performing PET, was implemented with PET variables combined with the top five features of the former model.
Results
Seventy-five PD patients were enrolled (33 PD-MCI and 42 noPD-MCI). PD-MCI vs. noPD-MCI resulted in older and showed worse gait patterns, mainly characterized by increased dynamic instability and reduced step length; when comparing amyloid PET data, the two groups did not differ. Regarding the machine learning analyses, evaluation metrics were satisfactory for Model 1 overcoming 80% for accuracy and specificity, whereas they were disappointing for Model 2.
Conclusions
This study demonstrates that machine learning implemented with specific clinical features and gait variables exhibits high accuracy in predicting PD-MCI, whereas amyloid PET imaging is not able to increase prediction. Additionally, our results prompt that a data mining approach on certain gait parameters might represent a reliable surrogate biomarker of PD-MCI.
Spinocerebellar ataxia type 2 (SCA2) is the second most frequent autosomal dominant inherited ataxia worldwide. We investigated the capability of magnetic resonance imaging (MRI) to track in vivo ...progression of brain atrophy in SCA2 by examining twice 10 SCA2 patients (mean interval 3.6 years) and 16 age- and gender-matched healthy controls (mean interval 3.3 years) on the same 1.5 T MRI scanner. We used T1-weighted images and tensor-based morphometry (TBM) to investigate volume changes and the Inherited Ataxia Clinical Rating Scale to assess the clinical deficit. With respect to controls, SCA2 patients showed significant higher atrophy rates in the midbrain, including substantia nigra, basis pontis, middle cerebellar peduncles and posterior medulla corresponding to the gracilis and cuneatus tracts and nuclei, cerebellar white matter (WM) and cortical gray matter (GM) in the inferior portions of the cerebellar hemisphers. No differences in WM or GM volume loss were observed in the supratentorial compartment. TBM findings did not correlate with modifications of the neurological deficit. In conclusion, MRI volumetry using TBM is capable of demonstrating the progression of pontocerebellar atrophy in SCA2, supporting a possible role of MRI as biomarker in future trials.
Aim
We investigated the value of serial cardiac
18
F-FDG PET-MRI in Anderson–Fabry disease (AFD) and the potential relationship of imaging results with FASTEX score.
Methods and results
Thirteen AFD ...patients underwent cardiac
18
F-FDG PET-MRI at baseline and follow-up. Coefficient of variation (COV) of FDG uptake and FASTEX score were assessed. At baseline, 9 patients were enzyme replacement therapy (ERT) naïve and 4 patients were under treatment. Two patients presented a FASTEX score of 0 indicating stable disease and did not show any imaging abnormality at baseline and follow-up PET-MRI. Eleven patients had a FASTEX score > 20% indicating disease worsening. Four of these patients without late gadolinium enhancement (LGE) and with normal COV at baseline and follow-up had a FASTEX score of 35%. Three patients without LGE and with abnormal COV at baseline and follow-up had a FASTEX score ranging from 30 to 70%. Three patients with LGE and abnormal COV at baseline and follow-up had a FASTEX score between 35 and 75%. Finally, one patient with LGE and normal COV had a FASTEX score of 100%. Of the 12 patients on ERT at follow-up, FASTEX score was significantly higher in those 4 showing irreversible cardiac injury at baseline compared to 8 with negative LGE (66 ± 24 vs. 32 ± 21,
p
= 0.03).
Conclusion
18
F-FDG PET-MRI may be effective to monitor cardiac involvement in AFD.
Pooling radiomic features coming from different centers in a statistical framework is challenging due to the variability in scanner models, acquisition protocols, and reconstruction settings. To ...remove technical variability, commonly called batch effects, different statistical harmonization strategies have been widely used in genomics but less considered in radiomics. The aim of this work was to develop a framework of analysis to facilitate the harmonization of multicenter radiomic features extracted from prostate T2-weighted magnetic resonance imaging (MRI) and to improve the power of radiomics for prostate cancer (PCa) management in order to develop robust non-invasive biomarkers translating into clinical practice. To remove technical variability and correct for batch effects, we investigated four different statistical methods (ComBat, SVA, Arsynseq, and mixed effect). The proposed approaches were evaluated using a dataset of 210 prostate cancer (PCa) patients from two centers. The impacts of the different statistical approaches were evaluated by principal component analysis and classification methods (LogitBoost, random forest, K-nearest neighbors, and decision tree). The ComBat method outperformed all other methods by achieving 70% accuracy and 78% AUC with the random forest method to automatically classify patients affected by PCa. The proposed statistical framework enabled us to define and develop a standardized pipeline of analysis to harmonize multicenter T2W radiomic features, yielding great promise to support PCa clinical practice.
Radiomics is rapidly advancing in precision diagnostics and cancer treatment. However, there are several challenges that need to be addressed before translation to clinical use. This study presents ...an ad-hoc weighted statistical framework to explore radiomic biomarkers for a better characterization of the radiogenomic phenotypes in breast cancer. Thirty-six female patients with breast cancer were enrolled in this study. Radiomic features were extracted from MRI and PET imaging techniques for malignant and healthy lesions in each patient. To reduce within-subject bias, the ratio of radiomic features extracted from both lesions was calculated for each patient. Radiomic features were further normalized, comparing the z-score, quantile, and whitening normalization methods to reduce between-subjects bias. After feature reduction by Spearman's correlation, a methodological approach based on a principal component analysis (PCA) was applied. The results were compared and validated on twenty-seven patients to investigate the tumor grade, Ki-67 index, and molecular cancer subtypes using classification methods (LogitBoost, random forest, and linear discriminant analysis). The classification techniques achieved high area-under-the-curve values with one PC that was calculated by normalizing the radiomic features via the quantile method. This pilot study helped us to establish a robust framework of analysis to generate a combined radiomic signature, which may lead to more precise breast cancer prognosis.
PDF
![[18F]FDG uptake of the norm...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/2191-219X/small "[18F]FDG uptake of the normal spinal cord in PET/MR imaging: comparison with PET/CT imaging")
