Jan 18, 2019 – Uro Today
Dr. Johannes Rübenthaler presented the case for using contrast-enhanced ultrasound for assessing cystic renal masses. Dr. Rübenthaler notes that contrast agents for CT imaging are iodine-based contrast media, with relative contraindications of GFR <30 ml/min and hyperthyroidism. For an MRI, paramagnetic contrast media has relative contraindications of GFR <30 ml/min, nephrogenic systemic fibrosis, and fear of cerebral deposition. Alternatively, contrast-enhanced ultrasound contrast agents do not rely on renal or thyroid function and have a high safety profile. The composition of these agents include a (i) shell – comprised of palmitic acid, albumin, interface-active substances, and lipids; (ii) core – comprised of air and perfluorocarbon gas. Visualization during contrast-enhanced ultrasound requires a high mechanical index setting.
Dr. Rübenthaler notes that there are three phases to assess the vascularization of renal cysts:
1. Arterial phase: 10-15 seconds
2. Portal phase: 30 seconds – 2 minutes
3. Delayed phase: 2-5 minutes
There are also nuances to the Bosniak classification of renal cysts that have been applied to findings on contrast-enhanced ultrasound imaging:
Bosniak I: no contrast enhancement
Bosniak II: no contrast enhancement or discrete contrast enhancement of the septa
Bosniak IIF: discrete contrast enhancement of the walls or septa
Bosniak III: multiple contrast-enhancing septa
Bosniak IV: multiple contrast-enhancing septa and irregular contrast enhancing soft tissue components
Dr. Rübenthaler concluded with several take-home points regarding contrast-enhanced ultrasound:
There are key differences to the contrast-enhanced ultrasound Bosniak classification of cystic masses compared to the CT classification often used for second opinions or to follow-up renal cysts
This imaging modality using color Doppler sonography provides additional dynamic information
For the patient, there is no radiation and the contrast media used is less nephrotoxic.
Author: Zachary Klaassen, MD, MSc – Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia, Twitter: @zklaassen_md, at the 16th Meeting of the European Section of Oncological Urology, #ESOU19, January 18-20, 2019, Prague, Czech Republic
Presentation by: Johannes Rübenthaler, MD, Department of Radiology, Ludwig-Maximilians University of Munich, Munich, Germany
