Faculty Bibliography

Retrograde intrarenal surgery (RIRS) is highly successful at eliminating renal stones of various sizes and compositions. As urologists are taking on more complex procedures using RIRS, this has led to an increase in operative (OR) times. Our objective was to determine the best predictor of OR time in patients undergoing RIRS. We retrospectively reviewed the records of patients undergoing unilateral RIRS for solitary stones over a 10 year time span. Stones were fragmented and actively extracted using a basket. Variables potentially affecting OR time such as patient age, sex, BMI, lower pole stone location, volume, Hounsfield units (HU), composition, ureteral access sheath (UAS) use, and pre-operative stenting were collected. Multivariable linear and stepwise regression was used to evaluate the predictors of OR time. There were 118 patients that met inclusion criteria. The median stone volume was 282.6 mm³ (IQR 150.7-644.7) and the mean OR time was 50 min (±25.9 SD). On univariate linear regression, stone volume had a moderate correlation with OR time (y = 0.022x + 38.2, r ²Â = 0.363, p < 0.01). On multivariable stepwise regression, stone volume had the strongest impact on OR time, increasing time by 2.0 min for each 100 mm³ increase in stone volume (p < 0.001). UAS added 13.5 (SE 3.9, p = 0.001) minutes and renal lower pole location added 9 min (SE 4.3, p = 0.03) in each case they were used. Pre-operative stenting, HU, calcium oxalate stone composition, sex, and age had no significant effect on OR time. Amongst the main stone factors in RIRS, stone volume has the strongest impact on operative time. This can be used to predict the length of the procedure by roughly adding 2 min per 100 mm³ increase in stone volume.

Blastomycosis is a fungal infection rarely seen in clinical practice. Endemic to the Midwestern United States as well as the Canadian provinces of Manitoba and Ontario, Blastomyces dermatitidis characteristically involves the skin and lungs. Central nervous system (CNS) involvement, although a rare complication of this disease, can be fatal. The current literature on CNS blastomycosis primarily centers on the spectrum of traditional imaging features of T1- and T2-weighted imaging with which this entity can present. However, here we present the direct histopathologic correlation of the imaging findings of solitary mass like CNS blastomycosis, with an emphasis on the association of diffusion restriction within the lesion with a granulomatous immune response.