CT-guided discitis-osteomyelitis biopsies: needle gauge and microbiology results

To compare the microbiology results and needle gauge for CT-guided biopsies of suspected discitis-osteomyelitis.

All CT-guided biopsies performed for suspected discitis-osteomyelitis at our institution between 2002 and 2019 were reviewed. Biopsy location, needle type and gauge, microbiology, pathology, and clinical and imaging follow-up were obtained through chart review. Yield, sensitivity, specificity, and accuracy were calculated. A pairwise analysis of different needle gauges was also performed with calculations of odds ratios. Naïve Bayes predictive modeling was performed.

241 (age: 59 ± 18 years; 88 [35%] F, 162 [65%] M) biopsies were performed. There were 3 (1%) 11 gauge (G), and 13 (5%) 12-G biopsies; 23 (10%) 13-G biopsies; 75 (31%) 14-G biopsies; and 90 (37%) 16-G, 33 (14%) 18-G, and 4 (2%) 20 G biopsies. True disease status (presence of infection) was determined via either pathology findings (205, 86%) or clinical and imaging follow-up (36, 14%). The most common true positive pathogen was Staphylococcus aureus (31, 33%). Overall biopsy yield, sensitivity, specificity, and accuracy were 39%, 56%, 89%, and 66%, respectively. Pooled biopsy yield, sensitivity, specificity, and accuracy was 56%, 69%, 71%, and 69% for 11-13-G needles and 36%, 53%, 91%, and 65% for 14-20-G needles, respectively, with an odds ratio between the two groups of 2.29 (P = 0.021). Pooled biopsy yield, sensitivity, specificity, and accuracy was 48%, 63%, 85%, and 68% for 11-14-G needles and 32%, 49%, 91%, and 64% for 16-20-G needles, respectively, with an odds ratio between the two groups of 2.02 (P = 0.0086).

The use of a larger inner bore diameter/lower gauge biopsy needle may increase the likelihood of culturing the causative microorganism for CT-guided biopsies of discitis-osteomyelitis.