FEASIBILITY OF WHOLE BODY DIFFUSION WEIGHTED IMAGING IN DETECTING BONE METASTASIS ON 3.0T MR SCANNER

Objective To evaluate the feasibility of whole body diffusion weighted imaging (DWI) in bone metastasis detection using bone scintigraphy as comparison. Methods Forty-five patients with malignancy history were enrolled in our study. All the patients received the whole body DWI and bone scintigraphy scan within 1 week. The magnetic resonance (MR) examination was performed on 3.0T MR scanner using embedded body coil. The images were reviewed separately by two radiologists and two nuclear medicine physicians, who were blinded to the results of the other imaging modality. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the two techniques for detecting bone metastasis were analyzed. Results A total of 181 metastatic lesions in 77 regions of 34 patients were detected by whole body DWI, and 167 metastatic lesions in 76 regions of 31 patients were identified by bone scintigraphy. The patient-based sensitivity and PPV of whole body DWI and bone scintigraphy were similar (89.5% vs. 81.6%, 97.1% vs. 91.2%), whereas, the patient-based specificity and NPV of whole body DWI were obviously higher than those of bone scintigraphy (85.7% vs. 57.1%, 60.0% vs. 36.4%). Ten regions negative in scintigraphy but positive in whole body DWI, mainly located in spine, pelvis, and femur; nine regions only detected by scintigraphy, mainly located in skull, sternum, clavicle, and scapula. The region-based sensitivity and specificity of whole body DWI were slightly higher than those of bone scintigraphy (89.5% vs. 88.4%, 95.6% vs. 87.6%). Conclusion Whole body DWI reveals excellent concordance with bone scintigraphy regarding detection of bone metastasis, and the two techniques are complementary for each other.

Partial improvement in performance of patients with severe Alzheimer's disease at an early stage of fornix deep brain stimulation

Deep brain stimulation is a therapy for Alzheimer＇s disease（AD） that has previously been used for mainly mild to moderate cases. This study provides the first evidence of early alterations in performance induced by stimulation targeted at the fornix in severe AD patients. The performance of the five cases enrolled in this study was scored with specialized assessments including the Mini-Mental State Examination and Clinical Dementia Rating, both before and at an early stage after deep brain stimulation. The burden of caregivers was also evaluated using the Zarit Caregiver Burden Interview. As a whole, the cognitive performance of patients remained stable or improved to varying degrees, and caregiver burden was decreased. Individually, an improved mental state or social performance was observed in three patients, and one of these three patients showed remarkable improvement in long-term memory. The conditions of another patient deteriorated because of inappropriate antipsychotic medications that were administered by his caregivers. Taken together, deep brain stimulation was capable of improving some cognitive aspects in patients with severe AD, and of ameliorating their emotional and social performance, at least at an early stage. However, long-term effects induced by deep brain stimulation in patients with severe AD need to be further validated. More research should focus on clarifying the mechanism of deep brain stimulation. This study was registered with ClinicalTrials.gov（NCT03115814） on April 14, 2017.

The Use of CT Perfusion to Determine Microvessel Density in Lung Cancer: Comparison with FDG-PET and Pathology

Objective： To investigate the validity of CT perfusion in assessing angiogenic activity of lung cancer. Methods： Fifty-six patients with lung cancer scheduled for elective surgical resection received 16-slice helical CT perfusion imaging. Time-density curve （TDC）, blood flow （BF）, blood volume （BV）, mean transmit time （MTT） and permeability surface area product （PS） were calculated. 18F-deoxyglucose-positron emission tomography （FGD-PET） was carried out in 14 out of the 56 patients to calculate standardized uptake values （SUVs）. Tumor microvessel density （MVD） was examined using CD34 immunohistochemical staining of the resected tumor tissue. Pearson’s correlation analysis was used to evaluate potential correlation between CT perfusion parameters and MVD or SUV. Results： Average time to peak height （TPH） of the TDCs （including two types of TDC） was 24.38±5.69 seconds. Average BF, BV, MTT and PS were 93.42±53.45 ml/100g/min,93.42±53.45 ml/100g,6.83±4.51 s and 31.92±18.73 ml/100g/min, respectively. Average MVD was 62.04±29.06/HPF. The mean SUV was 6.33±3.26. BF was positively correlated with MVD （r=0.620,P0.01） and SUV （r=0.891, P0.01）. PS was also positively correlated with SUV （r=0.720, P0.05）. A positive correlation was also observed between tumor MVD and SUV （r=0.915, P0.01）. Conclusions： CT perfusion imaging is a reliable tool to evaluate the tumor neovascularity of lung cancer.

A comparison between 18F-FDG PET/CT and classical physical examination package for cancer screening in asymptomatic Chinese patients

To the Editor:Cancer is the leading cause of death in China.[1]With rapid economic development,18F-fluorodeoxyglucose(FDG)positron emission tomography(PET)/computed tomography(CT)for screening cancer in asymptomatic patients is gaining popularity in China.PET/CT is a type of molecular imaging technology,which uses a specific tracer for localization and quantification of the disease at a molecular level.[2]However,the utility of such screening is still controversial.[3]Based on the past clinical experience,the previous physical examination protocol has been optimized,and a classical physical examination protocol has been set up at the author’s study center.So far,there is no evidence to know which approach was better for cancer screening in asymptomatic individuals.