DYNAMIC COMPUTED TOMOGRAPHY TO MEASURE TISSUE PERFUSION IN SPONTANEOUS CANINE TUMORS

Dynamic computed tomography (CT) is widely used in humans to determine tumor perfusion via time–attenuation curves. Five types of time–attenuation curves have been identified and shown to have prognostic relevance in humans. The goal of our study was to assess the feasibility of this technology in spontaneous canine tumors and to determine time–attenuation curves and perfusion patterns in different tumor types. Thirty-one dogs with tumors accessible for biopsy were evaluated (15 carcinomas, 16 sarcomas). Dynamic CT was performed at the level of the largest tumor cross-section. Time–attenuation curves were calculated and ratios from the tumor to a contralateral artery were derived for wash-in, peak attenuation, time to peak attenuation, wash-out, and perfusion. Median perfusion was significantly higher and median time to peak ratio was significantly shorter in carcinomas and bone sarcomas compared with soft tissue sarcomas ( P =0.03 and 0.01). There was a trend of lower median upslope and wash-out ratio in soft tissue sarcomas in comparison with carcinomas ( P =0.06 and 0.09). Although peak ratio was lowest in soft tissue sarcomas, differences were not significant ( P =0.3). The most common type of time–attenuation curve for all tumors had a slow to moderately rapid wash-in with a low to moderate attenuation peak followed by a plateau phase. In conclusion, dynamic CT is feasible and time-activity curve-derived measurements differed between spontaneous canine tumors. More data has to be collected in a larger number of patients and correlated with response to treatment and outcome.     

THREE-DIMENSIONAL ULTRASONOGRAPHIC IN VITRO IMAGING OF LESIONS OF THE MENISCUS AND FEMORAL TROCHLEA IN THE EQUINE STIFLE

The purpose of this in vitro study was to evaluate the value of three-dimensional (3D) ultrasonography for the diagnosis of equine meniscal and trochlear ridge lesions under in vitro conditions. Lesions were created in the isolated meniscus and femoral trochlea of 25 cadaver stifle joints. Cylindric, conic, and cuboid lesions were created on the trochlear ridge. Five different meniscal tear configurations were created. A total of 107 lesions of the trochlear ridge and 103 lesions of the meniscus were created. 3D ultrasonography was performed in a waterbath, using a 7.5 MHz 3D scanner. Trochlear ridge lesions were seen as either hypoechoic or anechoic breaks in continuity or as irregular notches. One-hundred and one out of the 107 trochlear lesions were visible using 2D ultrasonography whereas 104 out of the 107 lesions could be seen using the 3D Cine mode. Three lesions could not be detected by either technique. Eighty-five out of the 103 meniscal lesions were seen with 2D ultrasonography and 90 with 3D Cine mode. Radial tears and horizontal tears were the least commonly visualized 3D. The 3D Cine mode led to a small improvement in lesion detection. 3D ultrasound could be considered as an extension and refinement of the ultrasound techniques already in use and can increase the diagnostic capabilities. However, technical improvements have to be achieved before 3D ultrasound can be used in the daily practice for diagnosis of equine stifle joint disorders.     

Basin-scale advection and population persistence of Calanus finmarchicus

Advection of Calanus finmarchicus in the eastern North Atlantic was analysed using a particle-tracking model based on the Hamburg Shelf Ocean Model (HAMSOM). Quasi-static seasonal mean flowfields were simulated, archived and interpolated to represent a climatological-mean annual cycle. Particles had a simple prescribed depth profile comprising deep overwintering, spring ascent, a shallow-water phase followed by descent to overwintering depth. Export routes for C. finmarchicus from the model area were identified to the south of Greenland and to the north of the Lofoten Basin. Self-sustaining overwintering areas were identified by observing how closely particles returned to their origins after one calendar year. Several such areas were found, notably in the Norway and Lofoten Basins, and in the Færoe–Shetland Channel. The particle tracking was run for up to 10 years to demonstrate persistence of these cycles. Known features of the winter and summer distributions of C. finmarchicus were reproduced by the model. The success of the HAMSOM in simulating both the shallow and deep circulation of the eastern North Atlantic and Norwegian Sea was critical to the identification of these spatio-temporal cycles of C. finmarchicus.