Local maxima in multimodality image registration based on mutual information is discussed in this paper. Particle swarm optimization (PSO) and filter preprocessing based on hamming window is used to search the registration parameters. Simulations have been done to illustrate that after low-pass filter preprocessing local maxima is eliminated to a great extent. In most case the global maxima can be found by PSO. Simulations illustrate the efficiency and accuracy of this method in registration strategy.
Algorithms ; Artifacts ; Diagnostic Imaging ; methods ; Humans ; Image Enhancement ; methods ; Image Processing, Computer-Assisted ; methods ; Subtraction Technique

Objective To investigate w hether the iterative reconstruction (iDose 4 ) technique improves imaging quality of the low-radiation-dose w hole brain CT perfusion (CTP). Methods Thirty-five consecutive patients w ith clinical y suspected ischemic stroke w ere col ected. Bril iance 256 iCT w as used to perform low-radiation-dose w hole brain CTP, and the filtered back projection (FBP) and iDose 4 algorithm w ere used to conduct image reconstruction. The noise and signal to noise ratio of the 2 kinds of reconstruction algorithms, as w el as the imaging quality of each parameter map w ere compared. Results The effective dose of the w hole brain CTP w as 2.2 mSv. Compared w ith FBP, the noise of each region of interest in the iDose4 Tmax map was decreased significantly ( P<0.05) and the signal to noise ratio was increased significantly (P<0.05). The imaging quality scores (median, interquartile range) reconstructed by FPB group w ere significantly low er than by iDose 4 for cerebral blood flow (CBF) map ( 5.00 [3.00-6.00]vs. 6.00 [5.00-6.00]; Z= -2.784, P=0.005), cerebral blood volume (CBV) map ( 6.00 [5.00-6.00] vs. 6.00 [6.00-7.00]; Z= -3.674, P<0.001), and mean transit time (MTT) map (4.00 [3.00-5.00] vs. 5.00 [4.00-6.00]; Z=3.394, P=0.001). The proportions of the poor quality in CBF map ( 34.3%vs. 11.4%;χ2 =7.036, P=0.030), CBV map (11.4%vs.2.9%; χ2 =7.485, P=0.024 ) and MTT map (28.6%vs.11.4%;χ2 =5.318, P=0.070) reconstructed by FBP w ere significantly higher than by iDose 4 . Conclusions The iDose4 technique may improve imaging quality of low er-radiation-dose CTP.

Objective To evaluate the efficacy of double percutaneous nephrostomy combined with ureter occlusion stent in treating cervical cancer complicated with vesicovaginal fistula after radiotherapy. Method A prospective analysis was taken for 12 patients with cervical cancer complicated with vesicovaginal fistula after radiotherapy who were diagnosed by gynecological examination, imaging and cystoscopy. All patients received concurrent double percutaneous nephrostomy and ureter occlusion stent implantation.The improvement of symptoms and postoperative complications were observed.The number of white blood cells in urine,renal function,number of diapers in daily use(pieces),daily vaginal and urethral exudate, pain score,physical status (ECOG) score and quality of life score (KPS) before and 7 d after the procedure were compare by the paired Student's t test. Results Twelve patients were successfully implanted 24 ureter occlusion stents after successful nephrostomy. Postoperatively, urinary fistula immediately disappeared in all patients.One week after operation,bilateral hydronephrosis disappeared in 4 patients, renal insufficiency and renal function returned to normal in 4 patients. There were significant differences in the number of white blood cells in urine,the number of diapers in daily use,the daily vaginal and urethral exudate,pain score,KPS and ECOG score compared with before and 7 d after the procedure(all P<0.05).There was no significant difference in the creatinine and urea nitrogen (all P>0.05). No serious complications occurred after the operation.Conclusion Double percutaneous nephrostomy combined with ureter occlusion stent can effectively and safely treat cervical cancer complicated with vesicovaginal fistula after radiotherapy.

Objective: To investigate the microbiological test, antibiotic sensitivity and surgical treatment of periprosthetic joint infection(PJI) cases in post total hip arthroplasty (THA) and total knee arthroplasty (TKA) patients. Methods: A retrospective cross-sectional survey was conducted on 318 patients who underwent THA or TKA in 9 clinical centers in Beijing from January 2014 to December 2016.The data of microbiology, antibiotic sensitivity and surgical treatment were collected.The average age of patients was (62.3±13.1) years old (range: 21-86 years old), including 145 males and 173 females.The body mass index was (25.6±3.8) kg/m ² (range: 15.6-38.1 kg/m²). Results: In total, 318 patients had microorganisms detected by periprosthetic tissue culture or synovial fluid culture, 209 cases (65.7%) had Gram-positive bacteria, 29 cases (9.1%) had Gram-negative bacteria, 10 cases (3.1%) had fungi, 3 cases (0.9%) had non-tuberculous mycobacteria, 72 cases (22.6%) were negative, 69 cases (21.7%) had methicillin-resistant bacteria. The antibiotic sensitivity results showed that the overall resistance rate of penicillin, cefuroxime, amoxicillin+clavulanic acid was 79.9%, 69.9%, and 68.1%, respectively; meropenem, vancomycin, and linezolid resistance rate was 0. For the treatment methods of hip and knee PJI, two-stage revision surgery acounted for 72.9% (108/148) and 64.1% (109/170), respectively. One-stage revision surgery accounted for 21.6% (32/148) and 7.6% (13/170), and open debridement surgery accounted for 4.7%(7/148) and 26.4% (45/170). Conclusions Gram-positive bacteria was still the main pathogen of PJI.The methicillin-resistant bacteria and rare bacteria should be payed attention to. The Majority of hip and knee PJI cases were treated by two-stage revision surgery.