Impact of an online reference system on the diagnosis of rare or atypical abdominal tumors and lesions.

The purpose of the present study is to evaluate whether an online reference system (ORS, STATdx Elsevier, Amsterdam, Netherlands) impacts finding the histologically confirmed diagnosis of rare or atypical abdominal tumors and lesions in radiologic imaging. In total, 101 patients with rare tumor entities or lesions and atypical manifestations of common tumors were enrolled retrospectively. Blinded readings were performed by four radiologists with varying levels of experience, who reported on: (a) correct diagnosis (CD), (b) time needed to find the diagnosis, and (c) diagnostic confidence, initially without followed by the assistance of the ORS. The experienced reader (3 years of experience post-residency, CD 49.5%), as well as the advanced reader with 1 year of experience post-residency (CD 43.6%), and a resident with 5 years of experience (CD 46.5%) made the correct diagnosis more frequently compared to the less experienced reader (CD 25.7%). A significant improvement in making the correct diagnosis was only achieved by the advanced reader, the resident with 5 years of experience (CD with ORS 58.4%; p < 0.001). The advanced reader with 1 year of experience post-residency improved slightly (CD ORS 47.5%). The experienced reader (CD ORS 50.5%) and the less experienced reader (CD ORS 27.7%) did not improve significantly. The overall subjective confidence increased significantly when ORS was used (3.2 ± 0.9 vs. 3.8 ± 0.9; p < 0.001). While the ORS had a positive impact on making the correct diagnosis throughout all readers, it favored radiologists with more clinical experience rather than inexperienced residents. Moreover, the ORS increased the diagnostic confidence of all radiologists significantly. In conclusion, the ORS had no significant impact on the diagnosis of rare or atypical abdominal tumors and lesions except for one reader. The greatest benefit is the increase in diagnostic confidence.

Atovaquone for Prophylaxis of Toxoplasmosis after Allogeneic Hematopoietic Stem Cell Transplantation.

Toxoplasmosis and infections by other opportunistic agents such as Pneumocystis jirovecii constitute life-threatening risks for patients after allogeneic hematopoietic stem cell transplantation. Trimethoprim/sulfamethoxazole (TMP-SMX) has been well established for post-transplant toxoplasmosis and pneumocystis prophylaxis, but treatment may be limited due to toxicity. We explored atovaquone as an alternative and compared it with TMP-SMX regarding toxicity and efficacy during the first 100 days after transplantation in 155 consecutive adult stem cell recipients. Eight patients with a prior history of TMP-SMX intolerance received atovaquone as first-line prophylaxis. TMP-SMX was used for 141 patients as first-line strategy, but 13 patients (9.2%) were later switched to atovaquone due to TMP-SMX toxicity or gastrointestinal symptoms. No active toxoplasmosis or active P. jirovecii infection developed under continued prophylaxis with either TMP-SMX or atovaquone. However, for reasons of TMP-SMX and/or atovaquone toxicity, 7 patients were unable to tolerate any efficacious toxoplasmosis prophylaxis and therefore obtained inhalative pentamidine as P. jirovecii prophylaxis but no toxoplasmosis prophylaxis. Importantly, 2 of these patients developed severe toxoplasmosis. In summary, atovaquone appears as a valid alternative for at least some post-transplant patients who cannot tolerate TMP-SMX. This should be further confirmed by multicenter trials.