Diagnostic Value of Volume-Based Fluorine-18-Fluorodeoxyglucose PET/CT Parameters for Characterizing Thyroid Incidentaloma

OBJECTIVE: To assess clinical value of fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) for differentiation of malignant from benign focal thyroid incidentaloma. MATERIALS AND METHODS: This retrospective study included 99 patients with focal thyroid incidentaloma of 5216 non-thyroid cancer patients that had undergone PET/CT. PET/CT semi-quantitative parameters, volume-based functional parameters, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of thyroid incidentaloma were assessed. Receiver-operating characteristic (ROC) analysis was conducted and areas under the curve (AUC) were compared by Hanley and McNeil test to evaluate usefulness of maximum standardized uptake value (SUVmax), MTV and TLG, as markers for differentiating malignant from benign thyroid incidentalomas. RESULTS: Of 99 thyroid incidentalomas, 64 (64.6%) were malignant and 35 (35.4%) were benign. Malignant thyroid incidentalomas were larger (1.8 cm vs. 1.3 cm, p = 0.006), and had higher SUVmax (11.3 vs. 4.8, p 0.05). A threshold TLG 4.0 of 2.475 had 81.3% sensitivity and 94.3% specificity for identifying malignant thyroid incidentalomas. CONCLUSION: Volume-based PET/CT parameters could potentially have clinical value in differential diagnosis of thyroid incidentaloma along with SUVmax.

Removal of gutta percha in root canal therapy with Pro Taper nickel titanium system / 局解手术学杂志

Objective To evaluate the results of different methods in removing the root canal gutta percha.Methods Select 60 man-dibular premolars with step-back techinique during root canal prepartion,and the mandibular premolars were stored for 2 weeks after AH-plus paste and gutta percha cold lateral condensation.And then they were randomly divided into 3 groups to remove the root canal filling.Group A were given manually cleaning and shaping with stainless steel instruments combined with chloroform.Group B were given Pro Taper nickel ti-tanium system.Group C were given Pro Taper nickel titanium system combined with microscopic ultrasound technology.The completion time of the 3 groups were recorded and the root canal wall cleanliness of the 3 groups were carefully observed.Results The competition time and amount of debris of apical foramen in group C were both significantly less than those of group A and group B,with statistically significant difference (P <0.05).And the cleanliness of root canal wall of group A was significantly better than that of group A and group B (P <0.05). Conclusion During the root canal retreatment,mechanically use Pro Taper nickel titanium system combined with microscopic ultrasound technology can improve the work efficiency and the cleanliness of root canal wall.

FDG-PET/CT and diffusion-weighted MRI evaluation of the early therapeutic effect of radiofrequency ablation for VX2 sarcomas in rabbits / 介入放射学杂志

Objective To discuss the value of diffusion-weighted MRI (DWI) and 18F-FDG-PET/CT in assessing the early therapeutic effect of radiofrequency ablation (RFA) for VX2 sarcomas in experimental rabbits. Methods VX2 sarcoma was inoculated at bilateral hind limbs in 14 New Zealand white rabbits to establish the animal models. The implanted VX2 tumor on one hind leg was treated with ultrasound-guided percutaneous RFA (study group), while no RFA was given to the VX2 tumor on the contralateral hind leg (control group). DWI-MRI was performed at 2 days after RFA, and 18F-FDG-PET/CT examination was employed at 3 days after RFA. The mean apparent diffusion coefficient (ADC) values and standard uptake value (SUV) of the untreated tumor and the ablated tumor were separately calculated. Taking the pathologic result as the gold standard, the consistency of DWI-MRI, PET/CT as well as the combination of DWI-MRI and PET/CT with the clinical diagnosis was separately evaluated by Kappa test. Results Before RFA, DWI-MRI demonstrated that the VX2 tumor was characterized by hypo-intensity signal on T1 and hyper-intensity signal on T2 with ring-shaped enhancement on T1-weighted image; PET/CT showed that the tumor had nodular or ring-shaped 18F-FDG accumulation. After RFA, DWI-MRI revealed that the VX2 tumor was manifested as hyper-intensity signal on T1 and slight higher density on T1 with slight enhancement on contrast-enhanced T1-weighted image; PET/CT showed lowered accumulation of 18F-FDG. The mean ADC value of the ablated tumor was (1.52 ± 0.24) × 10-3 mm2/s, which was obviously higher than that of the un-ablated tumor, that was (1.09 ± 0.12) × 10-3 mm2/s, the difference was statistically significant(P0.05). The Kappa value of the consistency between combination of DWI-MRI with PET/CT and pathology was 0.786, which was significantly different from the result by simple DWI-MRI or simple PET/CT evaluation (P< 0.05). Conclusion Both ADC value of DWI-MRI and SUV value of PET/CT are useful indexes for evaluating the early therapeutic effect of RFA. Both DWI-MRI and PET/CT have their respective advantages, nevertheless, combination use of both can effectively improve the evaluation of curative effect for VX2 tumor after RFA in experimental rabbits.

Contrast-enhanced MRA of pulmonary artery combined with pulmonary perfusion imaging in pigs: a comparative study with DSA / 第二军医大学学报

Objective:To optimize the injection protocol of contrast medium for contrast-enhanced MRA (CEMRA) of pulmonary artery and to evaluate the diagnostic value of CEMRA and pulmonary perfusion imaging (PPI) in an experimental model of acute pulmonary embolism. Methods:CEMRA and PPI were performed in 6 normal pigs with different doses of gadolinium contrast agent (5ml, 10ml, 15ml, 20ml and 25ml) at an injection rate of 3ml/s, and 3 pulmonary embolism models were injected with 20 ml contrast agent at 3 ml/s. DSA was also performed for comparison. Results:The signal intensities and the signal to noise ratios of the pulmonary arteries kept increasing with the dose increase of the contrast agent, but the best angio-pulmonary contrast dose was 10-15ml (0.25-0.375mmol/kg), while the optimal dose for PPI was 15-20ml (0.375-0.5mmol/kg). Although CEMRA demonstrated less obstructed pulmonary arteries than DSA (5/10 vs 8/10)did, it detected all obstructions when combined with PPI. The pulmonary infarction zones showed wedge-shaped perfusion defects on the PPI images, with the signal intensities lower than those of the normal areas (137.86±45.32 vs 330.14±46.52, P<0.001). Conclusion:It is suggested that the optimal dose of the contrast agent is 0.25mmol/kg to 0.375mmol/kg for CEMRA, and 0.375mmol/kg to 0.5mmol/kg for lung perfusion. CEMRA combined with PPI may be better than DSA in demonstrating pulmonary embolism.

Dynamic enhanced multi-slice spiral CT in evaluation of blood flow patterns of solitary pulmonary nodules with enhancement / 中国肺癌杂志

<p><b>BACKGROUND</b>To investigate the methods of dynamic enhanced multi-slice spiral CT in evaluation of blood flow patterns of solitary pulmonary nodules (SPNs) with enhancement.</p><p><b>METHODS</b>Seventy-eight patients with SPNs (≤4 cm) with strong enhancement underwent dynamic multi-slice spiral CT (Marconi Mx8000) scan before and after contrast enhancement by injecting contrast material with a rate of 4 mL/s. For the 40 patients in protocol one, one scan was obtained every 2 seconds during 15-45 and 75-105 seconds after injection, while for the 38 patients in protocol two, one scan was obtained every 2 seconds during 11-41 and 71-101 seconds. For all the patients, one scan was obtained every 30 seconds during 2-9 minutes. The section thickness was 2.5 mm for lesions ≤3 cm and 5 mm for lesions > 3 cm. Standard algorithm was used in the image reconstruction. Precontrast and postcontrast attenuation on every scan was recorded. The perfusion, peak height, ratio of peak height of the SPN to that of the aorta and mean transit time were calculated.</p><p><b>RESULTS</b>The peak height, perfusion, ratio of peak height of the SPN to that of the aorta and mean transit time in malignant SPNs were 34.85 Hu±10.87 Hu, 30.37 ml/(min*100 g)±11.14 ml/(min*100 g), 13.78%± 3.96% , 14.19 s±6.19 s respectively in protocol one, while those in protocol two were 36.62 Hu±10.75 Hu, 30.01 ml/(min*100 g)±8.10 ml/(min*100 g), 14.70 %±4.71%, 13.91 s±4.82 s respectively. No statistically significant differences were found between the peak height (t= 0.673, P=0.503), perfusion (t= 0.152 , P=0.880), ratio of peak height of the SPN to that of the aorta (t= 0.861, P=0.393) and mean transit time (t= 0.199, P=0.843) in malignant SPNs measured in protocol one and those measured in protocol two. All mean transit time in protocol two (36/36) were obtained, but only part of them (25/32) were obtained in protocol one.</p><p><b>CONCLUSIONS</b>Dynamic enhanced multi-slice spiral CT is a non-invasive method for quantitative evaluation of blood flow patterns of SPNs with enhancement and scans beginning at 11 seconds after injection of contrast material is suggested.</p>

The Dynamic-enhanced MR Angiography of the Liver : A Comparision Study with DSA and CTAP / 实用放射学杂志

Objective To assess the role of dynamic-enhanced MR angiography (MRA) by comparing with DSA and CT arterial portography (CTAP).Methods Sixteen patients with liver diseases (mainly HCC) were included in the study. All patients underwent dynamic MRI of the liver using SENSE, digital subtraction angiography (DSA) and CTAP within two-week. MRA was reconstructed from raw data. The arterial phase of the modified MRA was compared with DSA for the evaluation of hepatic arteries and the portal phase compared with CTAP. In dynamic MRI, a fixed dosage (20 ml) of contrast medium and scan timing were used. Results The main branches and variations of the hepatic arterial system were well displayed on the dynamic-enhanced MRA, although the distant intrahepatic branches were showed poorly. Portal veins on MRV were showed as well as or even superiorly to CTAP. In addition, the inferior vena cava (IVC) was well demonstrated on MRV in most cases. MRV revealed 1 vascular variation which was not found on DSA and CTAP.Conclusion The dynamic-enhanced MRA using SENSE was a effective modality in demonstrating the hepatic vascular system. It may be a first choice modality in preoperative evaluation of orthotopic liver transplantation.