Faculty Bibliography

Gout is a common crystal-induced arthritis, in which monosodium urate (MSU) crystals precipitate within joints and soft tissues and elicit an inflammatory response. The causes of elevated serum urate and the inflammatory pathways activated by MSU crystals have been well studied, but less is known about the processes leading to crystal formation and growth. Uric acid, the final product of purine metabolism, is a weak acid that circulates as the deprotonated urate anion under physiologic conditions, and combines with sodium ions to form MSU. MSU crystals are known to have a triclinic structure, in which stacked sheets of purine rings form the needle-shaped crystals that are observed microscopically. Exposed, charged crystal surfaces are thought to allow for interaction with phospholipid membranes and serum factors, playing a role in the crystal-mediated inflammatory response. While hyperuricemia is a clear risk factor for gout, local factors have been hypothesized to play a role in crystal formation, such as temperature, pH, mechanical stress, cartilage components, and other synovial and serum factors. Interestingly, several studies suggest that MSU crystals may drive the generation of crystal-specific antibodies that facilitate future MSU crystallization. Here, we review MSU crystal biology, including a discussion of crystal structure, effector function, and factors thought to play a role in crystal formation. We also briefly compare MSU biology to that of uric acid stones causing nephrolithasis, and consider the potential treatment implications of MSU crystal biology.

PURPOSE: To determine the sensitivity, specificity, and accuracy of contrast-enhanced magnetic resonance (MR) imaging performed 1 month after localized chemotherapy as a measure of tumor response, before detectable changes in size. MATERIALS AND METHODS: This trial was approved by the authors' institutional review board and was compliant with the Health Insurance Portability and Accountability Act (HIPAA). Inclusion criteria selected patients receiving chemoembolization for hepatocellular carcinoma (HCC) with MR imaging within 2 months before treatment, in addition to MR imaging after treatment at 1 month and 6 months. Pathology was used as a surrogate for 6-month follow-up if the patient underwent interval transplantation. The final population consisted of 23 tumors (occurring within 21 patients). MR imaging studies were evaluated separately by two radiologists. Tumors were scored as showing complete loss of enhancement or as showing some residual tissue enhancement. Changes in T1 and T2 signal and perilesional enhancement were tabulated and recorded. Lesion size was also measured on all MR imaging studies by using a one-dimensional measure of the longest dimension. Increase in tumor size from 1-6 months of 20% or greater was used as confirmation of residual disease. In 5 of 23 tumors, review of pathology served as the surrogate standard. Sensitivity, specificity and accuracy were computed for each rater. RESULTS: The sensitivity, specificity, and accuracy of 1-month follow-up MR imaging were 71.4-85.7%, 100%, and 91.3-95.7%. There was a high degree of agreement between the two readers for both the 1-month (kappa = 0.88) and 6-month (kappa = 1.0) MR imaging studies. CONCLUSIONS: This investigation shows high accuracy for using tumor enhancement features on 1-month posttherapy MR imaging to predict residual disease after chemoembolization of HCC.

PURPOSE: To evaluate the efficacy of thrombolysis with the EndoWave peripheral infusion system in the treatment of patients with massive pulmonary embolism (PE) as compared to patients treated with catheter-directed thrombolysis. MATERIALS AND METHODS: Ten patients (five men and five women; age range, 31-85 years; mean age, 54.20 years) with massive acute PE (17 lesions) were treated with ultrasonography (US)-assisted catheter-directed thrombolysis with the Endowave system. All patients had hypoxia and dyspnea. No patient had contraindication for thrombolysis. Angiographic findings, duration of lysis, dose of thrombolytics used, and procedural complications were recorded. Thrombolytics used were urokinase, tissue-type plasminogen activator (tPA), and Reteplase. RESULTS: Complete thrombus removal was achieved in 13 of the 17 lesions (76%), near complete thrombolysis was achieved in three lesions (18%), and partial thrombolysis was achieved in one lesion (6%). The mean time of thrombolysis was 24.76 hours +/- 8.44 (median, 24 hours). The mean dose of tPA used for the Endowave group was 0.88 mg/h +/- 0.19 (13 lesions). CONCLUSIONS: US-assisted catheter-directed thrombolysis is an effective method for treating massive thrombolysis. It has the potential to shorten the time of lysis and lower the dose of thrombolytics.