[en] Objective: To investigate the detection rate and diagnostic value of multi-slice spiral CT scan in detecting fish bone impaction in the esophagus. Methods: Experimental group: 30 fresh water fish bones from three variety classes were divided into three groups with length of (23.36±0.15), (28.51± 0.07) and (30.89±0.10) mm, and diameter of (4.49±0.31), (1.78±0.09) and (0.49±0.07) mm. The fish bones were put into esophagus models in three different types including parallel, perpendicular and oblique. MSCT with axial scan combined with three dimensional reconstruction technique and plain X-ray film ( CR and DR) were used to examine the model. The relations of the number and rate of fish bones were compared between MSCT and X-ray film. Clinical group: MSCT imaging were performed in 20 cases proved by esophageal endoscope or clinical operation, among which 11 cases received plain X-ray film (CR and DR), 15 cases received Barium-soaked cotton and 17 cases received endoscope. Paired Chi-square test was used to compare the differences of detection of fishbone by the different ways. Results: In experimental group: All the 90 cases (100%) fish bones of three different species were clearly revealed on MSCT image; only 60 cases (66.7%) fish bones were revealed by plain X-ray film (CR and DR). The number and rate of fish bones detected by MSCT was higher than that of plain X-ray film (CR and DR) (χ²=28.03, P<0.01). In clinical group: 20 cases were made right diagnosis by MSCT, and the location and size of fish bone in the esophagus, the surrounding and complications of esophagus could be clearly demonstrated on MSCT image. Two cases detected by plain X-ray film (CR and DR); 9 cases detected by Barium-soaked cotton; 14 cases detected by endoscopy. The number and rate of fish bones detected by MSCT was higher than that of plain X-ray film (CR and DR) (χ²=7.11, P<0.05) and Barium-soaked cotton (χ²=4.17, P<0.05). Conclusions: The sensitivity and detection rate of fish bone with MSCT was high and could evaluate the surrounding and complications of the esophagus. MSCT could be used as the first examination of impacted fish bones in the esophagus. (authors)

[en] Objective To observe the rates of repeated computed tomographic scans (CTs) in a cohort of patients with coronavirus disease-2019 (COVID-19) and to assess the validity of repeat CTs. Methods: Each CT was recorded, and the validity of the repeated CTs was assessed. Results: The 394 patients underwent a total of 1493 CTs. Of the 394 patients, 260 received at least one non-value-added CT. Both the total number of CTs (median, 4; inter-quartile range (IQR), 3-5) and non-value-added CTs (median, 1; IQR, 0-1) per patient were strongly related to the disease duration (R2 = 0.566 for total CTs, R2 = 0.432 for non-value-added CTs, p < 0.001). The proportion of non-value-added CTs was potentially higher after 3 weeks from symptom onset (>35%). Conclusions: There was a high rate of repeat CTs for the COVID-19 patients, and the proportion of non-value-added CTs increased with disease duration. Follow-up CT should be avoided without clinical decline. Advances in Knowledge: As COVID-19 is impacting health care systems across the globe, we believe in our findings that serial chest CT imaging has limited clinical utility in basically stable COVID-19 patients, will help relieve some of this burden. (authors)

[en] Objective: To evaluate the predictability of MSCT perfusion in the restorability of renal function of hydronephrotic kidneys with unilateral partial ureteric obstructed rabbit model as to explore a method to predict the restorability of renal function of hydronephrotic kidneys and to investigate the changes of MSCT perfusion parameters during the course of the restore of renal function. Methods: Establish a unilateral partial ureteric obstructed rabbits hydronephrotic model. Hydronephrotic rabbits were grouped as control, 2, 4 and 8 week (G₂w, G₄w and G₈w) after obstruction and the later 3 groups of rabbits were reared for further 4 weeks after the obstruction was released. MSCT perfusion scanning was performed and the specimen was made into histological slices with HE staining. Results: BF and BV value of renal cortex and medulla of G₂w after obstruction [(864 ± 32) ml·100 g^-1·min^-1, (19.5±0.9) ml/100 g (cortex); (182.1 ± 7.5) ml·100 g^-1·min^-1, (8.37±0.51) ml/100 g (medulla)] was released restored in substance and approached that of control [( 899 ± 63) ml ·100 g^-1· min^-1, (21.6 ± 1.4 ) ml/100 g (cortex); (193.5 ± 16.5) ml·100 g^-1·min^-1, (8.50±0.54) ml/100 g (medulla)] while there was no significant restore in that of G₄w and G₈w after obstruction [(525±15) ml·100 g^-1·min^-1, (12.8 ± 0.6)ml/100 g(G₄w); (512 ± 10) ml·100 g^-1·min^-1, (9.4±1.0) ml/100 g(G₈w)] was released. Histologically, there was a positive correlation between the duration of obstruction and the seriousness of pathologic changes. Conclusion: MSCT perfusion can provide information not only morphologically but also about renal perfusion of hydronephrotic kidneys. (authors)

[en] Objective: To establish the rabbit model of hyperthyroidism and to evaluate the feasibility of multi-model MR imaging for assessing the extraocular muscles (EOMs). Methods: 15 New Zealand rabbits were injected intraperitoneally with 3, 5, 3-triiodothyronine solution in the dosage of 0.2 ml/kg body weight every two days and 15 rabbits in the control group were injected intraperitoneally with the same dosage of 0.9% saline. The weights of all rabbits were recorded. MRI and venous blood samples were obtained before and after the rabbit model establishment. The levels of T3, T4 and TSH were measured by enzyme-linked immunosorbent assay. MRI included three-dimensional double-echo steady state (3D-DESS), T₂-Dixon and T₂-mapping sequences. Two radiologists independently evaluated the maximum diameters, cross-sectional areas, T₂ relaxation time and water fractions of inferior rectus muscles. Results: The study was completed successfully on 10 experiment rabbits and 14 control rabbits. The T₂ relaxation time and the maximum diameters of the inferior rectus muscles were significantly increased in the experiment group (P = 0.039, < 0.001). Conclusion: T₂-mapping can detect the thyroid hormone induced biochemical changes of EOMs. The 3D-DESS sequence can accurately evaluate the morphology changes of EOMs in hyperthyroidism. (authors)

[en] Objective: To investigate the efficacy of high-resolution reduced field-of-view (r-FOV) diffusion-weighted magnetic resonance imaging (DWI) of the adrenal gland. Methods: 19 consecutive healthy volunteers underwent 3 T MRI including r-FOV DWI (19) and conventional full field-of-view (f-FOV) DWI (9). Image quality including the morphology and signal intensities of the adrenal glands was evaluated qualitatively by two abdominal imaging radiologists with four point scale. Apparent diffusion coefficient (ADC) values of bilateral adrenal glands as well as thickness of the glands were measured on r-FOV DWI by one radiologist. The data were analyzed using the SPSS 17.0 statistical software. Results: The image quality of r-FOV DWI was significantly higher than f-FOV DWI (P < 0.05) with high inter-observer agreement whereas the ADC values of r-FOV DWI were significantly lower than f-FOV DWI. There was no significant difference in ADC values and thickness between the left and right adrenal glands. Conclusion: r-FOV DWI can clearly show the shape and signal intensities of the adrenal gland with higher spatial resolution and may possibly allow more accurate diagnosis of adrenal disease. (authors)

[en] Objective: To assess the feasibility of low-dose cerebral CT angiography (CTA). Methods: From August 2012 through June 2013, 62 patients who underwent 64-detector-row CTA were randomly divided to two groups using conventional method of 120 kV and 80 mL of intravenous Iohexol (17 men, 14 women, age range: 37-76 years, median: 63 years, body weight: 40-71 kg) or low-dose method of 80 kV and 50 mL of intravenous Iohexol followed by 30 mL of normal saline (16 men, 15 women, age range: 36-74 years, median: 59 years, body weight: 38-73 kg). The CT values of the M1 segments of the middle cerebral arteries (MCA), basilar arteries, noise and signal-to-noise ratios on the axial images were determined. The quality of the circles of Willis on the 3 D volume rendered images was scored. The radiation dose indexes including CTDI_vol and DLP were recorded. Results: The CT values of the M1 segments of MCA and basilar arteries were significantly (P < 0.05) higher using the low-dose method (307.19, 306.38) than those of conventional method (303.01, 302.25). The noise was lower and the image quality scores of the circles of Willis were higher with the low-dose method as well. Conclusion: Low-dose cerebral CTA improves the image quality and significantly decrease the dose of radiation and iodinated contrast. (authors)

[en] Objective: To evaluate the image quality and the diagnostic value of low radiation, low dose and isotonic low concentration iodine contrast pulmonary computed tomography angiography (CTPA) protocol in pulmonary embolism. Methods: Eighty patients with clinically suspected pulmonary embolism and BMI < 28 kg/m² underwent pulmonary CTA on a 64-MDCT scanner (GE Discovery CT750 HD). Eighty patients were divided into two groups (group A: n = 40, 80 kV, Auto mA, 20 ml 270 mg I/ml, 60%FBP + 40% ASIR; group B: n = 40, 120 kV, Auto mA, 40 ml 370 mg I/ml, 100%FBP). Image quality was assessed, using a five-point scoring scale.Intraarterial density was measured in the common pulmonary artery trunk, the main right and left pulmonary arteries, lobar arteries, and then the average CT value was calculated. Image quality score, Average CT value, noise, SNR, CNR, CTDIvol and DLP were compared between the two groups using t-test. The occurrence rate of the superior vena cava iodine contrast agent sclerosis artifacts and the positive rate of pulmonary embolism were compared between the two groups, using Chi-square test. Results: PE was found in 33 patients (14 in group A, 19 in group B) , and there was no difference of the positive rate of PE between two groups(35.0% vs 47.5%, χ² = 1.289, P > 0.05). Overall 4-6 pulmonary artery branches were clearly displayed in all the cases. The image quality scores for two groups were 3.9 ± 0.6 and 4.0 ± 0.7, respectively. There was no statistical difference between two groups (t = 0.632, P > 0.05). The superior vena cava iodine contrast agent sclerosis artifacts were reduced in group A(28 cases vs. 36 cases, χ² = 10.362, P < 0.01). The average CT value and noise in group A [(426.8 ± 84.8), (14.9 ± 1.5) HU, respectively] was higher than those in group B [(359.4 ± 75.3), (7.4 ± 1.4) HU, respectively], which was statistically significant (t = 3.758, 22.848, respectively; P < 0.01). However, the SNR (28.8 ± 6.3) and CNR (24.5 ± 6.1) in group A were lower than those in group B(SNR 50.4 ± 14.7, CNR 42.9 ± 13.8). There was statistically significant difference between two groups (t = 8.522, 7.669, respectively; P < 0.01 both). The CTDIvol[(3.3 ± 0.3) mGy]and DLP[(101.4 ± 11.9)mGy·cm] in group A were significantly lower than those in group B [CTDIvol(9.6 ± 0.6) mGy, DLP (328.5 ± 37.3) mGy·cm]. The difference between two groups was statistically significant(t = 56.393, 36.675, respectively, P < 0.01 both). Conclusions: The low radiation, low dose and isotonic low concentration iodine contrast CTPA protocol shows pulmonary artery branches of 4-6 levels, reduces radiation exposure and contrast media volume compared with the conventional pulmonary CTA, and achieves the same positive rate of PE in comparison of the conventional CTPA. It can meet the clinical needs. (authors)

[en] Highlights: • Reduced FOV DWI manifested superior image quality and lesion conspicuity to the conventional DWI. • Lower ADC values correlated with advanced cervical carcinoma regardless of FOV. • ADC may be helpful for the evaluation of FIGO staging of cervical carcinoma. To evaluate imaging quality (IQ) and International Federation of Gynecology and Obstetrics (FIGO) staging of reduced field-of-view (r-FOV) diffusion-weighted imaging (DWI) in cervical carcinoma (CC).

[en] To investigate the feasibility of non-contrast-enhanced MR angiography (NCE-MRA) in evaluating the morphology and blood supply of left gastric vein (LGV) in patients with gastroesophageal varices. Between March 2021 and October 2022, patients with gastroesophageal varices and who underwent NCE-MRA were retrospectively reviewed. In order to evaluate the blood supply of LGV, superior mesenteric vein (SMV) and splenic vein (SV) were visualized separately by using inflow-sensitive inversion recovery sequence. Two radiologists independently assessed the image quality, determined the origination and the blood supply of LGV, and measured the diameter of LGV. The origination and diameter of LGV were compared between NCE-MRA and contrast-enhanced CT. Differences in blood supply were compared between LGVs with different originations. A total of 53 patients were enrolled in this study and the image quality was categorized as good or excellent in 52 patients. No significant differences were observed in visualizing the origination and the diameter of LGV between NCE-MRA and contrast-enhanced CT (p > .05). The blood supply of LGV was related to its origination (p < .001). Most LGVs with SV origination were supplied by SV. If LGV was originated from the portal vein (PV), about 70% of them were supplied by both SV and SMV. Compared with LGVs with SV origination, LGVs with PV origination showed more chance to receive blood from SMV (p < .001). Non-contrast-enhanced MR angiography appears to be a reliable technique in evaluating the morphology and blood supply of LGV in patients with gastroesophageal varices. Non-contrast-enhanced MR angiography provides valuable information for the management of gastroesophageal varices. Especially, it benefits patients with renal insufficiency.

[en] Objective: To evaluate the degree of contrast enhancement, reduction of radiation exposure and contrast dose requirement of low-kV 64-slice CT angiography (MSCTA). Methods: Iopamidol solutions with 370 mgI/mL diluted to concentrations of 1.5% and 2.5% were placed in 30 rubber tubes each with tube diameter of 2 mm to simulate large blood vessels. The 30 tubes with 1.5% Iopamidol solution were scanned on a 64-slice CT scanner using the same tube current of 40 mA and varying tube voltages of 120 kV, 100 kV and 80 kV. All 1.25 mm-thick slices were transferred to an ADW4.3 workstation. The CT densities of different slices from the 30 tubes were measured ten times to calculate the average CT densities for the 3 different tube voltages. The radiation doses with different scanning parameters were recorded as CTDIvol The 30 tubes with 2.5% Iopamidol solution were then scanned and analyzed using the same scanning parameters and data processing method. Results: With 1.5% Iopamidol concentration, there was significant (P < 0.05) difference in the average CT densities among 120 kV (172.23 HU), 100 kV (208.64 HU) and 80 kV (262.05 HU). The same statistical trend was found with 2.5% Iopamidol concentration. The CTDIvol of 120 kV, 100 kV and 80 kV were 2.68 mGy, 1.66 mGy and 0,83 mGy, respectively. There was no significant difference between average CT densities of 1.5% Iopamidol concentration scanned at 80 kV (262.05 HU) and that of 2.5% Iopamidol scanned at 120 kV (267.35 HU). All rubber tubes had similar tube brightness, image detail and VR image definition. Conclusions: With decreasing kV in 64-slice CT scanning, the CT density increases whereas changing the tube current with constant tube voltage does not affect the CT density. Low kV scanning is important in reducing the dose of X-ray radiation and contrast agent. (authors)