Quantitative biomarkers for liver metastases: comparison of MRI diffusion-weighted imaging heterogeneity index and fluorine-18-fluoro-deoxyglucose standardised uptake value in hybrid PET/MR.

AIM: To investigate the ability of apparent diffusion coefficient (ADC) heterogeneity index to discriminate liver metastases (LM) from normal-appearing liver (NAL) tissue as compared to common magnetic resonance imaging (MRI) metrics, and to investigate its correlation with 2-[18F]-fluoro-2-deoxy-d-glucose (18F-FDG) positron-emission tomography (PET) standardised uptake value (SUV). MATERIALS AND METHODS: Thirty-nine liver metastases in 24 oncology patients (13 women, 11 men; mean age 56±13 years) with proven LM from heterogeneous sources were evaluated on a PET/MRI system. Abdominal sequences included Dixon and diffusion-weighted imaging (DWI) protocols with simultaneous PET. Tissue heterogeneity was calculated using the coefficient of variance (CV) of the ADC, and compared in LM and in NAL tissue of the same volume in an adjacent portion of the liver. The correlations between various ADC measures and PET SUV in distinguishing LM from NAL were evaluated. RESULTS: A good correlation was found between ADCcv and SUVpeak (r=0.712). Moderate inverse correlation was found between ADCmin and SUVpeak (r=-0.536), and a weak inverse correlation between ADCmean and SUVpeak (r=-0.273). There was a significant difference between LM and NAL when ADCcv (p<0.0001) and ADCmin (p=0.001) were used. Receiver operating characteristic (ROC) analysis of SUV, ADCcv, ADCmin, and ADCmean produced an AUC of 0.989, 0.900, 0.742, and 0.623 respectively. CONCLUSIONS: The ADCcv index is a potential biomarker of LM with better correlation to 18F-FDG PET SUVpeak than conventional MRI metrics, and may serve to quantitatively discriminate between LM and NAL.

Early 68GA-PSMA PET/MRI acquisition: assessment of lesion detectability and PET metrics in patients with prostate cancer undergoing same-day late PET/CT.

AIM: To compare lesion detectability and positron-emission tomography (PET) metric measurements between early-PET/magnetic resonance imaging (MRI) acquisition and same-day PET/computed tomography (CT). MATERIALS AND METHODS: The study was approved by the institutional review board and written informed consent was obtained from all patients. Twenty-one patients underwent non-time-of-flight (TOF) PET/MRI immediately following 68GA-prostate-specific membrane antigen (PSMA) tracer injection in two steps: firstly, early prostate PET/MRI (pPET/MRI) and early whole-body (WB) PET/MRI (wbPET/MR) followed by WB TOF PET/CT (wbPET/CT). Lesion detectability was compared between wbPET/MRI and wbPET/CT while PET metric measurements were compared between pPET/MR, wbPET/MRI, and wbPET/CT. RESULTS: Sixty-one and 63 lesions were found on wbPET/MRI and wbPET/CT, respectively (K=0.95, 95% confidence interval (CI)=0.89-1.0) with very good correlation between PET metric measurements (r=0.91; p=0.001). Bland-Altman plots demonstrated a mean percentage difference between wbPET/CT with wbPET/MRI of 34.4% with 95% limits of agreement (LOA) between -39% to 107.9% for metabolic tumour volume (MTV) and a mean difference of 30% with LOA between -13.4% to 73.4% for peak standardised uptake value (SUVpeak). CONCLUSION: Early PET/MRI demonstrates very good lesion detectability agreement and correlation with PET metrics compared to same-day PET/CT. Nevertheless, LOA are far beyond the clinically acceptable range, and therefore, PET/CT and early PET/MRI metrics cannot be used interchangeably.

The Role of 18F-FDG PET/CT on Staging and Prognosis in Patients with Small Cell Lung Cancer.

BACKGROUND: We evaluated 18F-FDG PET/CT in small cell lung cancer (SCLC) staging and assessed metabolic (SUVmax, MTV and TLG) and morphologic (CTvol) variables as predictors for overall survival (OS) and progression-free survival (PFS). METHODS: Patients with newly diagnosed, histopathology-confirmed SCLC, who underwent 18F-FDG PET/CT were evaluated. A Cox proportional hazard model was used to determine the association between the primary tumour SUVmax, MTV, TLG and CTvol with OS and PFS. Similar evaluations were performed when hilar/mediastinal lymphadenopathy was included [total SUVmax (TSUVmax), total MTV (TMTV) and total TLG (TTLG)]. RESULTS: 55 patients were included. 18F-FDG PET/CT changed staging in 6/55 (10.9%) patients who were upstaged to extensive disease. TTLG (>443.8) was a significant variable for OS with HR=2.1 (CI 1.14-3.871, p=0.017). Patients with TTLG>443.8 had a median OS of 13.4 months compared to 25.7 months in patients with TTLG<443.8 (p=0.018). TMTV (>72.4) was significant for PFS with HR=2.3 (CI 1.11-4.8, p=0.025). A median PFS of 12.1 and 26.2 months was found with TMTV greater and less than 72.4, respectively (p=0.005). CONCLUSIONS: 18F-FDG PET/CT improved staging of patients with SCLC, and TTLG and TMTV can be used as prognostic variables for OS and PFS, respectively. KEY POINTS: • Identifying variables that predict the prognosis of patients with SCLC is important. • 18F-FDG PET/CT influences staging of patients with SCLC. • Metabolic parameters could be used as predictors for PFS and OS.

Survival Prognostic Value of Morphological and Metabolic variables in Patients with Stage I and II Non-Small Cell Lung Cancer.

BACKGROUND: The prognosis of patients with non-small cell lung cancer (NSCLC) is important, as patients with resectable disease and poor prognostic variables might benefit from neoadjuvant therapy. The goal of this study is to evaluate SUVmax, SUVmax ratio, CT volume (CTvol), metabolic tumour volume (MTV) and total lesion glycolisis (TLG) as survival prognostic markers. In addition, we defined two variables; MTV x SUVmax (MTVmax) and CTvol x SUVmax (CTvolmax) and assessed whether they can be used as prognostic markers. METHODS: Patients with stage I-II NSCLC who underwent 18 F FDG PET/CT and surgery were evaluated. Cox proportional-hazard model was used to determine the association between variables and survival. Similar analysis was performed in cases with no lymph node (LN) involvement. RESULTS: One hundred and eighty-one patients were included (at the end of the study, 140 patients were alive). SUVmax with a cut-off value of 8.2 was significant survival prognostic factor regardless of LN involvement (P = 0.012). In cases with no LN involvement, SUVmax and CTvol (≥7.1 ml) were significant survival prognostic factors with P = 0.004 and 0.03, respectively. CONCLUSIONS: SUVmax may be a useful prognostic variable in stage I-II NSCLC while morphologic tumour volume might be useful in cases with no lymph node involvement. KEY POINTS: • Identifying variables that predict the prognosis of patients with NSCLC is important. • SUVmax in primary lung tumour is a useful independent prognostic variable. • (CTvol) is an independent prognostic variable if no lymph nodes are involved.

Hyperbaric oxygen-induced seizures cause a transient decrement in cognitive function.

Hyperbaric oxygen-induced seizures are classified as brief, generalized tonic-clonic seizures. They are believed to cause no residual cognitive damage, although this has not been investigated in depth. In the present study, we examined whether hyperbaric oxygen-induced seizures cause impairment of behavioral and cognitive abilities. Cognitive status was assessed using four behavioral tests: Y-maze, novel object recognition, the elevated plus maze, and a passive avoidance task. Three time intervals were examined: 24h, and 7 and 30 days after the seizures. We found transient impairment of performance in the compressed group on three tests (the novel object recognition paradigm, the Y-maze paradigm, and the passive avoidance task). On the elevated plus maze test, the impairment persisted. The time interval to the appearance of deficits and to eventual recovery was not the same for the different tests. We conclude that hyperbaric oxygen-induced seizures result in transient impairment of performance on behavioral tests in a mouse model. Further investigation is required to establish the mechanism and location of injury, and to determine whether the performance decrement on the elevated plus maze test represents permanent damage or transient damage with slow resolution. These new findings should be taken into account when planning hyperbaric oxygen treatments, to ensure that the chosen protocol is therapeutic yet minimizes the risk of CNS oxygen toxicity.

Transient osteoporosis associated with hyperhomocystinemia: a possible role for hyperbaric oxygen therapy.

Transient osteoporosis of the hip is considered by some to be an early stage of avascular necrosis. Hyperbaric oxygen (HBO2) therapy, which may be of benefit in the treatment of avascular necrosis, might therefore be used in the treatment of transient osteoporosis of the hip. We present a case of transient osteoporosis associated with elevated levels of homocysteine in a 33-year-old white male, who was treated by HBO2. Treatment was administered at 2.5 ATA for 90 minutes once daily, five days per week. Regular follow-up examinations in the course of the HBO2 therapy revealed improvement in the patient's complaints and the findings of the physical examination. Repeated magnetic resonance imaging (MRI) performed after 40 and 90 sessions showed decreased edema and complete resolution of the edema, respectively. Evaluation 6 months after the completion of treatment revealed complete resolution of symptoms, with a normal physical examination.