Dynamic Brain Imaging Response to Spinal Cord Stimulation Differential Frequencies DiFY SCS-PET Clinical Trial.

OBJECTIVES: This study with sequential 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)-computed tomography (CT) scanning was designed to investigate any objective measurable effect of differential frequency stimulation (40 Hz, 4000 Hz, and 10,000 Hz) on specific pain matrix areas in patients who underwent spinal cord stimulation (SCS) for intractable lumbar neuropathic pain. MATERIALS AND METHODS: In this single-center, randomized, blinded study, four brain 18F-FDG PET scans were performed for each patient-at baseline before SCS implant and after 40-Hz, 4000-Hz, and 10,000-Hz stimulation. After 40-Hz stimulation for four weeks, patients were randomized 1:1 (4000 Hz/10,000 Hz), crossing over at another four weeks. 18F-FDG PET-CT brain scans acquired on the GE-Discovery 710 PET system (GE Healthcare, Chicago, IL) with 128-slice CT (250-MBq dose) were analyzed using the PMOD software (PMOD Technologies Ltd, Zurich, Switzerland). A total of 18 pain regions, the right and left prefrontal cortex (PFC), insula, anterior cingulate cortex (ACC), hippocampus, amygdala, primary somatosensory cortices, secondary somatosensory cortices (SSCII), thalami, parabrachial, and periaqueductal gray (PAG), were analyzed. RESULTS: A total of 14 patients received 40 Hz for four weeks before crossing over to 10,000 Hz/4000 Hz. A total of 57 PET-CT scans (15 for baseline and 14 each for 40 Hz, 4000 Hz, and 10,000 Hz) were analyzed for maximum standardized uptake value (SUVmax), with a statistically significant difference in SUVmax between 40 Hz and baseline (p = 0.002) and 4000 Hz and baseline (p = 0.001) when pooled across 18 pain matrices. There was no statistical difference in SUVmax between 10,000 Hz and baseline. The pooled analysis showed a proportionately higher thalamic region reduction (59.5%) in metabolic activity than other pain matrices, PFC (52%), insula (50%), ACC (52%), SSCII (49%), and PAG (52%). CONCLUSION: This large cohort of brain PET scans (n = 57) shows statistically significant differences in brain metabolic activity at 40 Hz and 4000 Hz from baseline, with effect on both nociceptive and affect-cognitive pathways (proportionately higher reduction in the thalamus), highlighting the possible mechanism of SCS. CLINICAL TRIAL REGISTRATION: The Clinicaltrials.gov registration number for the study is NCT03716557.

Assessment of Apparent Diffusion Coefficients and SUVs as Predicators of Histological Differentiation in Anal Squamous Cell Carcinoma.

AIM: The study aims to assess minimal apparent diffusion coefficient (ADCmin) and SUVmax as predictors of histological differentiation in patients with anal squamous cell carcinoma (ASCC) and to determine cutoff values for each histopathological tumor grade. PATIENTS AND METHODS: A retrospective study of 41 ASCC patients (14 males, 27 females; mean age, 65 ± 13 years) staged with FDG PET/CT and MRI (mean scan time interval, 21 ± 11 days). SUVmax and ADCmin values were measured and compared with histopathological tumor grading obtained from biopsy. RESULTS: The mean size and tumor volume were 3 ± 2 cm and 16.5 ± 27.3 cm3, respectively. The mean ADCmin values for well-, moderately, and poorly differentiated ASCC were 935 ± 179, 896 ± 123, and 637 ± 114, respectively. The mean SUVmax for well-, moderately, and poorly differentiated ASCC were 6.9 ± 1.8, 11.5 ± 4.1, and 13.4 ± 2.6, respectively. The difference in mean ADCmin values between poorly and moderately/well-differentiated tumors was statistically significant, whereas this was not significant between moderately and well-differentiated tumors. Differences in SUVmax values were statistically significant between poorly/moderately and well-differentiated tumors, whereas there was no statistical significance between poorly and moderately differentiated tumors. By combining the 2 modalities using cutoff values of 675 × 10-6 mm2·s-1 for ADCmin and 8.5 for SUVmax, it was possible to differentiate the tumor categories with a sensitivity, specificity, positive predictive value, and negative predictive value, respectively, of 84.6%, 96.4%, 91.7%, and 93.1% for well-differentiated ASCC, 76.5%, 87.5%, 81.3%, and 84% for moderately, and 90.9%, 89.3%, 76.9%, and 96.2% for poorly differentiated ASCC, respectively. CONCLUSIONS: ADCmin and SUVmax values correlated with the degree of differentiation in ASCC and can be used as predictors of tumor grading and aggressiveness. Combined ADCmin and SUVmax cutoff values can therefore be used for early patient risk stratification and treatment decision making.

Improving liver lesion characterisation using retrospective fusion of FDG PET/CT and MRI.

AIM: To compare retrospectively fused FDG PET/CT and MRI (PET/MRI) to FDG PET/CT and MRI for characterisation of indeterminate focal liver lesions as malignant or benign in patients with a known primary malignancy. MATERIALS AND METHOD: A retrospective review of 70 patients (30 females, 40 males; mean age 56 ±â€¯14 years) with 150 indeterminate lesions after FDG PET/CT and MRI (mean scan time interval 21 ±â€¯11 days). HERMES® software was used to fuse PET/CT and MRI scans which were reviewed by 2 readers using the Likert score (scale 1-5) to characterise lesions as benign (1-3) or malignant (4-5). Final diagnosis was determined by histopathology or follow up imaging. Results for fused PET/MRI were compared to PET/CT and MRI alone. RESULTS: For detection, MRI and fused PET/MRI detected all the lesions while PET/CT detected 89.4%. Characterisation of liver lesions as malignant on PET/CT alone yielded sensitivity, specificity, accuracy, PPV and NPV of 55.6%, 83.3%, 66.7%, 83.3%, 55.6% respectively and 67.6%, 92.1%, 80%, 89.3%, 74.5% for MRI, respectively. The sensitivity, specificity, accuracy, PPV and NPV for characterising lesions as malignant increased to 91.9%, 97.4%, 94.7%, 97.1%, 92.5% with PET/MRI fusion. The sensitivity, specificity, accuracy, PPV and NPV of fused PET/MRI for characterising lesions as malignant remained superior to PET/CT and MRI. CONCLUSION: Retrospective fusion of PET with MRI has improved characterisation of indeterminate focal liver lesions compared to MRI or FDG PET/CT alone.

Diffusion-weighted magnetic resonance imaging in cancer: Reported apparent diffusion coefficients, in-vitro and in-vivo reproducibility.

There is considerable disparity in the published apparent diffusion coefficient (ADC) values across different anatomies. Institutions are increasingly assessing repeatability and reproducibility of the derived ADC to determine its variation, which could potentially be used as an indicator in determining tumour aggressiveness or assessing tumour response. In this manuscript, a review of selected articles published to date in healthy extra-cranial body diffusion-weighted magnetic resonance imaging is presented, detailing reported ADC values and discussing their variation across different studies. In total 115 studies were selected including 28 for liver parenchyma, 15 for kidney (renal parenchyma), 14 for spleen, 13 for pancreatic body, 6 for gallbladder, 13 for prostate, 13 for uterus (endometrium, myometrium, cervix) and 13 for fibroglandular breast tissue. Median ADC values in selected studies were found to be 1.28 × 10(-3) mm(2)/s in liver, 1.94 × 10(-3) mm(2)/s in kidney, 1.60 × 10(-3) mm(2)/s in pancreatic body, 0.85 × 10(-3) mm(2)/s in spleen, 2.73 × 10(-3) mm(2)/s in gallbladder, 1.64 × 10(-3) mm(2)/s and 1.31 × 10(-3) mm(2)/s in prostate peripheral zone and central gland respectively (combined median value of 1.54×10(-3) mm(2)/s), 1.44 × 10(-3) mm(2)/s in endometrium, 1.53 × 10(-3) mm(2)/s in myometrium, 1.71 × 10(-3) mm(2)/s in cervix and 1.92 × 10(-3) mm(2)/s in breast. In addition, six phantom studies and thirteen in vivo studies were summarized to compare repeatability and reproducibility of the measured ADC. All selected phantom studies demonstrated lower intra-scanner and inter-scanner variation compared to in vivo studies. Based on the findings of this manuscript, it is recommended that protocols need to be optimised for the body part studied and that system-induced variability must be established using a standardized phantom in any clinical study. Reproducibility of the measured ADC must also be assessed in a volunteer population, as variations are far more significant in vivo compared with phantom studies.

Assessment of diffusion-weighted imaging for characterizing focal liver lesions.

In 150 patients, 153 hepatic lesions (39 metastases, 27 hemangiomas, 26 hepatocellular carcinomas, 25 cysts, 15 adenomas, 8 focal nodular hyperplasias, 5 abscesses, 4 hamartomas, and 4 cholangiocarcinomas) were evaluated during a 24-month period. Apparent diffusion coefficient (ADC) values of benign lesions (1.994×10(-3) mm(2) s(-1)) were significantly higher than ADC values of malignant lesions (1.070×10(-3) mm(2) s(-1)). Mean ADC value for solid benign lesions (1.143×10(-3) mm(2) s(-1)±0.214×10(-3) mm(2) s(-1)) was not significantly different from malignant lesions. ADC values did not allow differentiating malignant from benign solid lesions (area under the curve=0.61). ADC cutoff value threshold of 1.6×10(-3) mm(2) s(-1) yielded higher accuracy for differentiating benign from malignant lesions.

Remote sonographic interpretation: comparison of standardized video clips to still images.

OBJECTIVE: The aim of our study was to evaluate the role of standardized video clips compared with still images in the diagnostic accuracy of remote sonographic interpretation. METHODS: We compared the remote interpretation of sonographic examinations acquired with a standardized video clip approach to examinations performed with still images alone in 60 patients with various hepatic and extrahepatic pathologies. RESULTS: The use of video clips improved the diagnostic accuracy of sonographic studies interpreted remotely compared with the use of still images (p < 0.0001). The sensitivity, specificity, and positive and negative predictive values increased from 47.3% to 68.3%, 81.8% to 87.8%, 71.5% to 81%, and 63.8% to 74.5%, respectively. CONCLUSIONS: Standardized video clips are easy to obtain, less operator-dependent than still images, and can be transferred to remote sites without loss of important data. We recommend this method in remote interpretation (teleradiology and distant consultation) of sonographic examinations.

Anatomical and functional localization of ectopic parathyroid adenomas: 6-year institutional experience.

INTRODUCTION: Localization of ectopic parathyroid adenoma is highly important to guide surgery, thus reducing morbidity and rate of recurrent hyperparathyroidism. The aim of this study was to establish the incidence of ectopic parathyroid adenoma and evaluate the role of multimodality imaging in diagnosis. MATERIALS AND METHODS: We reviewed 656 imaging studies of patients referred for investigations of primary hyperparathyroidism. All patients suspected of having an ectopic adenoma had technetium-99m (99mTc) sestamibi (MIBI) and ultrasound of the neck. In addition, patients had cross-sectional imaging, either computed tomography (CT) or magnetic resonance imaging (MRI), in cases of suspected ectopic adenoma. Some patients also underwent angiography. Results were correlated with postoperative findings and histopathology to calculate sensitivity, specificity, positive and negative predictive values. The incidence of ectopic adenoma was also determined. RESULTS: In our series, the incidence of ectopic adenoma was 1.4%, which is lower than earlier published reports in the literature. Eleven patients showed ectopic uptake suspicious of a parathyroid adenoma on 99mTc MIBI. CT confirmed the diagnosis of ectopic adenoma in seven patients and MRI showed adenoma in two patients. Surgical and histopathological findings confirmed the diagnosis of ectopic parathyroid adenoma in nine patients. Sensitivity and specificity for ultrasound were 11 and 100%, respectively. 99mTc MIBI had sensitivity, specificity, positive and negative predictive values of 100, 86, 98 and 65%, respectively. The combination of 99mTc-MIBI with CT or MRI yielded the correct diagnosis in all cases, giving a sensitivity and specificity of 100%. CONCLUSION: The incidence of ectopic parathyroid adenoma is much lower than previously reported. Multimodality imaging in a tertiary referral centre is the ideal approach for accurate diagnosis.

[Intramural hemorrhage of the thoracic aorta]. / Hémorragie intramurale de l'aorte thoracique.

Intramural hemorrhage (IMH) of the thoracic aorta is a unique aortic syndrome. It is a spontaneous hemorrhage of the vasa vasorum (small vessels that run in the wall of an artery) in the wall of the aorta without an intimal tear, such as overt aortic dissection. IMH has a similar clinical profile, prognosis and can progress to aortic dissection. CT scan ensures the rapid diagnosis of IMH. Surgical treatment of IMH of the ascending aorta is necessary.