Objective To explore the effect of multi-detector computed tomography (MDCT)scan parameters and imaging post-processing methods on metallic artifacts,so as to achieve the perfection in reduction of artifacts caused by metallic implants.Methods Water phantom with titanium alloy steel plate was scanned under MDCT with alternating scan parameters including tube voltage, tube current,pitch and focal spot.The areas of image artifacts were measured and correlated with the scan parameters.Another 1 5 postoperative patients with vertebral implantation scaned with the conventional scan parameters were also included in the study.Ima-ging post-processing including multi-planar reconstruction (MPR),window width and level adjustment,and volume rendering tech-nique (VRT)was performed by using optimized and conventional methods,respectively,and then the image quality was evaluated. Results The areas of image artifacts under the differnt tube voltage,pitch,and focal spot were statistically different.With the in-crease of the tube voltage or the decrease of the pitch,the area of image artifacts decreased gradually.The area of image artifacts scanned with the small focal spot was smaller than the large one.There was no significant difference for the area of image artifacts scanned with the different tube currents.The metallic artifacts decreased by using the soft tissue algorithm (Kernel B40f)in the bone window reconstruction,wide windows (2 000 HU window width,600 HU window level)in observing,and VRT.Conclusion Selection of appropriate MDCT scan parameters and imaging post-processing methods can reduce the metal artifacts,improve the image quality and diagnosis.

Objective To discuss X-ray, CT and MR findings of primary bone lymphoma. Methods The X-ray, CT and MR findings of 6 cases with non-Hodgkin lymphoma of bone proved pathologically were retrospectively analysed.Results The average age of 6 cases was 51 years old and the lesions all localized at long bone(especially the metadiaphysis) and pelvis. Imaging findings included: osteolytic or moth-eaten bone destruction,surrounding soft tissue mass formation which generally exceeded the extents of bony changes, the cortex bone was destructed and discontinuity.Conclusion primary bone lymphoma has prevalent age and certain imaging specificity.

Objective To identify related anatomical parameters and the strongest risk predictor leading to patients with recurrent patellar instability.Methods 52 young patients with recurrent patellar instability that failed of conservative treatment were retrospec-tively evaluated by MRI.Measurements included parameters of patellar tracking,which was characterized by bisect offset index (BSO),trochlear congruence angle (CA)and patellar lateral tilt (PTA),and anatomical parameters of patellofemoral joint,which were characterized by the sulcus angle (SA),lateral trochlear inclination (LTI),trochlear facet asymmetry,trochlear depth,Insall-Salvati Ratio (ISR),Caton-Deschamps index (C-D)and tibial tuberosity-trochlear groove (TT-TG)distance.The collection data were analyzed including the Pearson's correlation and multiple stepwise regression analysis.Results The patellofemoral joint ma-lalignment was significantly correlated with LTI,TT-TG distance and ISR,but not or partly with the trochlear depth,SA,trochlear facet asymmetry and C-D.Linear regression models including LTI,TT-TG distance and ISR explained 0.58,0.47 and 0.43 of the va-riance in BSO,CA and PTA,respectively (P<0.001).And the standardized beta coefficient was largest for LTI,then were TT-TG distance and ISR.Conclusion At full extension of the knee,anatomical related factors measured on MRI explain some degree of re-current lateral patella shift and tilt,the strongest predictor among anatomical related factors that could lead to maltracking is LTI, and then are TT-TG distance and ISR.

Objective To investigate the site,MR signal types and morphological characteristics of ulnar nerve in cubital tunnel for healthy adults,in order to improve the awareness of ulnar nerve.Methods Unilateral elbow of forty healthy volunteers were scanned with MR,the sequences were as follows:T1-weighted-spin-echo,T2-weighted-spin-echo-fat-suppression,PD-weighted-spin-echo-fat-suppression,among 40,13 were supine,27 were prone.The site and MR signal types and morphological characteristics of ulnar nerve were observed,the long diameter and short diameter of the ulnar nerve on different axials were respectively measured.Results On axial,ulnar nerve was posterior to the medial condyle of the humerus at proximal elbow,lied between the flexor carpi ulnaris and the flexor digitorum profunds and superficialis muscles distally.The shape of the ulnar nerve was roundness or elliptic,the signal of 40 volunteers'(100％) ulnar nerve was isointensity on T1-weighted,the signal of 17 volunteers'(42.5％)ulnar nerve was isointense on T2-weighted or PD-weighted,the MRI signal of 23 volunteers' (57.5％) ulnar nerve was slight hyperintense on T2-weighted or PD-weighted,especially on the axial of medial condyle of humerus.The variation range of long diameter and short diameter of the ulnar nerve respectively were 1.4-3.8 mm,1.0-3.0 mm.Conclusion The certain location,MR signal types and morphological characteristics of normal ulnar nerve play an important role in the diagnosis of cubital tunnel syndrome.

Objective To study the value of MRI and proton magnetic resonance spectroscopy(H 1-MRS)for neonatal hypoxic-is-chemic encephalopathy(HIE).Methods Magnetic resonance imaging (MRI)and proton magnetic resonance spectroscopy (H 1-MRS)were performed in 30 cases of full-term neonates with HIE,and 10 infant control group without evidence of birth asphyxia. Cerebral MRI and H 1-MRS were performed within 1 5 days after birth.The results of H 1-MRS such as subwave crest values of me-tabolites in lesion areas were recorded.The data were analyzed statistically.Results (1)MRI showed abnormal fetures of HIE such as diffuse cerebral edema,loss of hyperintensity in the posterior limb of the internal capsule on T1 WI,gyrus sign,diffuse parenchy-mal hemorrhage,which could predict the severity of brain damage.(2)On H 1-MRS,the ratio of Lac/Cr in HIE group was much higer than that in control group,which was statistically significant (P <0.05).The ratio of Lac/Cr showed a rising trend with clini-cal grading of HIE.The ratio of NAA/Cr and NAA/Cho were lower in HIE group than that in control group (P <0.05),which showed a trend of gradually reduce with clinical grading of HIE.The difference between ratio of Glx-α/Cr in HIE group and control group was also significantly,the moderate-severe group was much higher than the mild group and control group.There was no sig-nificant difference in the ratio of Cho/Cr between the 4 groups.Conclusion The combination of MRI and H 1-MRS can objectively re-flect brain morphology and metabolic changes of HIE,and evaluate the severity of the brain injury,and provide an effective evidence for clinical diagnosis and treatment.

Objective To analyze the imaging performances and significance of Modic changes on X-ray,CT and MRI.Methods The imaging data (MR,CT and X-ray)of patients with low back pain were retrospectively analyzed.The selected patients’images were studied on the same work station by the two physician experts in muscle and bone imaging.A double-blind method was used. Firstly,MRI was used to sort the MC.Then,the alterations of the density in the lesions on X-ray plain film and CT image were measured.if the judgments of the two readers were inconsistent,another professor of radiology will join the discussion and consist-ent results will be got finally.The data were recorded using Excel 2010,and processed for statistical analysis using SPSS 1 6.0.Re-sults A total of 47 cases that met the requirements were collected which included 1 6 males and 31 females,aged from 32 to 76 years,with a median age of 56.0 years.A total of 93 on MRI endplate were changed.However,a part of lumbar endplates with MC on MRI images were displayed as higher density than normal vertebral body on the X-ray and CT reconstruction images (total of 36).The occurrence rates of Type Ⅰ,Type Ⅱ,Type Ⅰ/Ⅱ were 40.0%,14.8%,58.3%,respectively.But the occurrence rate of Type Ⅲ (100%)and hybrid Type which contained type Ⅲ were 100%.Conclusion Some Modic typeⅠ,Ⅱ,Ⅰ/Ⅱchanges in X-ray plain film, CT reconstruction images had a higher density,speculating that there is reactive new bone formation,which reflects the internal ver-tebral body bone mineralized rather than the change of the bone marrow.

Objective To analyze the correlation of intervertebral disc degeneration with the blood perfusion of its adjacent border of vertebral body by dynamic contrast‐enhanced MRI (DCE‐MRI) .Methods 3 .0T DCE‐MRI examinations were performed in 15 patients (50 discs) .Intervertebral discs from L1 to L5 were classified to normal group(17 discs) and degeneration group(33 discs) based on the Pfirrmann grading system .The DCE‐MRI pharmaeokinetic parameters of the region of interest(ROI):volume transfer constant (Ktrans ) ,blood volume(BV) and blood flow (BF) were obtained .Independent sample t test was used to compare normal group and de‐generation group .Results In normal group (n=17) ,the mean Ktrans ,BV and BF were (0 .036 2 ± 0 .011 2)min-1 ,(4 .81 ± 1 .17) mL/100 mL ,(5 .68 ± 1 .55) mL · min-1 · 100 mL -1 for the superior border of vertebral body ,and (0 .042 ± 0 .012 9)min-1 ,(5 .03 ± 0 .797) mL/100 mL ,(6 .02 ± 1 .28) mL · min-1 · 100 mL -1 for the inferior border of vertebral body .In degeneration group (n=33) ,the mean Ktrans ,BVand BF were (0 .030 4 ± 0 .011 2)min-1 ,(4 .22 ± 1 .03) mL/100 mL ,(4 .73 ± 1 .38) mL · min-1 · 100 mL-1 for the superior border of vertebral body ,and (0 .033 8 ± 0 .012 5) min-1 ,(4 .07 ± 0 .940) mL/100 mL ,(4 .72 ± 1 .43) mL · min-1 · 100 mL -1 for the inferior border of vertebral body .By statistical analysis :(1)There were no significant differences between superior border and inferior border of vertebral body in Ktrans ,BV and BF in normal group(t= -0 .98 ,-0 .479 ,0 .533 respectively ,P>0 .05 ) .(2)There were no significant differences between superior border and inferior border of vertebral body in K trans ,BV and BF in degeneration group(t= -0 .906 ,0 .497 ,0 .013 respectively ,P>0 .05) .(3)There were significant differences between normal group and degeneration group in Ktrans ,BV and BF(t= -2 .26 ,-3 .01 ,-2 .99 respectively ,P<0 .05) .Conclusion The bone marrow per‐fusion in degeneration group is decreased when compared to normal group with dynamic contrast‐enhanced MRI .Intervertebral disc degeneration correlates with the loss of its blood supply .

Objective To investigate the MR characteristics of ulnar nerve and muscles in cubital tunnel syndrome.Methods Twenty eight patients with cubital tunnel syndrome and 28 asymptomatic volunteers underwent MR imaging,MR neurography was performed by using an isotropic three dimensions T2 sampling perfection with application optimized contrasts using different flip angle evolutions (3D T2 SPACE)on 15 patients with cubital tunnel syndrome.To evaluate changes in T2 signal intensity of the ulnar nerve,regions of interest were placed in the center of the location of the highest apparent ulnar nerve signal intensity on the axial FS T2WI images and in normal muscle within the same image slice,and the ratio of signal intensity was calculated.The sensitivity of 3D T2 SPACE sequence in detecting cubital tunnel syndrome was determined.The standard t tests were used to assess whether ulnar nerve size and relative signal intensity in symptomatic patients were statistically different from normal volunteers.Results The cross-sectional area of ulnar nerve in 24 patients and 2 volunteers was enlarged,the signal intensity of ulnar nerve in 26 patients and 16 volunteers was increased.Increased signal and muscle atrophy adjacent to the ulnar nerve were detected in 4 patients.Cubital tunnel syndrome was detected in 14 patientson 3D T2 SPACE sequence.The mean ulnar nerve sizes in the symptomatic and normal group were (0.15±0.06)and (0.06±0.01)cm2 respectively,the mean relative signal intensities in the symptomatic and normal groups were (2.86± 1.45) and 1.57±0.39 respectively (t values were 2.220 and 4.546,P＜0.05).Conclusions Ulnar nerve size and T2 signal intensity were increased,in patients with cubital tunnel syndrome.In addition,muscles innervated by the ulnar nerve showed atrophy with increased T2 signal intensity.

Objective:To evaluate the application values of small FOV surface coil and BLADE sequence in MR imaging on assessment of talar cartilage injury of ankle joint under traction.Methods:The clinical and imaging data of 53 patients with ankle cartilage injury in the Affiliated Suzhou Hospital of Nanjing Medical University from December 2018 to July 2020 were prospectively analyzed. All patients underwent the following MR sequences: sequence Ⅰ was fast spin echo proton density weighted (FSE-PD) BLADE sequence with surface coil small FOV, and sequence Ⅱ was FSE-PD-BLADE imaging of small FOV under horizontal load traction of ankle joint. Paired sample Wilcoxon rank sum test was used to compare the thickness of talus dome cartilage, cartilage space and subjective assessment score of image quality (including the outline of the upper surface of the cartilage at the injury, the thickness of the cartilage layer at the injury, the rupture of the cartilage at the injury, the relationship between cartilage and subchondral bone, subchondral bone collapse or trabecular fracture line) between sequence I and sequence Ⅱ.Results:There was significant difference in the thickness of central cartilage of talus between sequence Ⅰ and sequence Ⅱ [0.70 (0.60, 0.90) mm and 0.80 (0.70, 0.90) mm, Z=-2.900, P=0.004, respectively]. There was no significant difference in the thickness of medial and lateral talus cartilage between sequence Ⅰ and sequence Ⅱ (P>0.05). There were significant differences between sequence Ⅰ and sequence Ⅱ in the center [0.10 (0, 0.15), 0.89(0.63, 1.00) mm], medial [0.10(0, 0.31), 1.20(0.70, 1.25) mm] and lateral cartilage space [0.18(0.08, 0.23), 0.90(0.76, 0.94)mm] (all P<0.001). As for the subjective assessment score of talus cartilage injury, except for score in subchondral bone collapse or bone trabecular fracture line between sequence Ⅱ and sequence Ⅰ ( Z=-1.480, P=0.139), significant differences were found in all other scores ( P<0.05). Conclusion:MRI of the ankle under traction is safe and feasible. Under the condition of horizontal traction, small FOV surface coil combined with BLADE sequence can better display talus cartilage injury.

Objective TostudythedistributioncharacteristicsofModicchanges(MCs)onlumbarvertebraeinthepatientswith lowbackpain.Methods LumbarvertebraeMRIresultsfrom276patients(male:104,female:172)wereanalyzedretrospetively.The MConlumbarvertebraewereclassifiedwithT1WI,T2WIandT2WI-FS,meanwhiletheincidence,predilectionsitesanddistribution characteristicsbyageandsexwerestatisticallyanalyzed.Results 139cases(50.4%)couldbeseenwith MC,including42malesand 97females;while137caseswerenormal(49.6%).Classifiedbygender,numbersofpatientswith MCinagegroup20－39 were7 (male)and11(female);inagegroup40－59,were15(male)and44(female);andinagegroup60－78,were20(male)and42(female). Amongatotalof2760vertebralendplates,2450 (88.8%)wereclassifiedasModicType0,65 (2.4%)asTypeⅠ,153 (5.5%)as TypeⅡ,3 (0.1%)asTypeⅢ,and89 (3.2%)as MixedType.ThenumbersofMCoccurringonendplatesofL5/S1,L4/5,L1/2 were108,103and15respectively.Conclusion MCTypeⅡoflumbarvertebraeisthemostprevalent,followedbythe MixedType and MCTypeⅠ.MCTypeⅢistheleast.Inallthreeagegroups,theincidencerateishigherinfemalepatientsthanthatinmales. Regardlessofthegender,theincidenceofMCislinearlypositivecorrelatedwithage.MCoccursmostlyonendplatesofL5/S1and L4/5,andrarelyonendplateofL1/2.