Canine urinary bladder transitional cell carcinoma tumor volume is dependent on imaging modality and measurement technique.

Transitional cell carcinoma is the most common cancer of the canine urinary tract. The inconsistent appearance of transitional cell carcinoma in patients introduces error if applying mathematic models for extrapolating total tumor volume from linear measurements. Reliable techniques to assess tumor size are important for monitoring treatment response. A method comparison study was performed comparing four techniques for calculating tumor volume were compared: (1 and 2) contoured tracing of tumor margins using serial computed tomography (CT) images using pre-(1) and postintravenous (2) contrast medium studies, (3) longest three linear dimensions using CT, and (4) longest three linear dimensions on abdominal ultrasound. Volumes of the transitional cell carcinoma tumor calculated by CT tracing techniques were significantly smaller than volumes calculated with an ellipsoid mathematic model using the linear measurements (P < 0.01). Intravenous contrast medium did not significantly change the volumes calculated from tracing tumor margins on CT for observer B; however, volumes differed for observer A. The volumes extrapolated from linear measurements using CT and ultrasound did not differ significantly. The interobserver reliability was highest for the precontrast CT contoured technique and was lowest using the ultrasound linear technique. Tumor volumes differed significantly between techniques of contoured tracing of the tumor margins on serial CT images compared to calculation of tumor volume from linear dimensions. The calculated volume of a transitional cell carcinoma depends upon the technique used. Characterizing the response of urinary bladder transitional cell carcinoma tumor size to therapy differs based on the method and modality used.

SPINAL MAST CELL TUMORS IN DOGS: IMAGING FEATURES AND CLINICAL OUTCOME OF FOUR CASES.

Published information regarding canine vertebral column mast cell tumors (MCTs) is limited. The objectives of this study were to report clinical and advanced imaging findings for a group of dogs with confirmed spinal MCT. Inclusion criteria for this retrospective case series were dogs with spinal magnetic resonance imaging (MRI) or computed tomography (CT) scans and a histological diagnosis of spinal MCT. Clinical, imaging, treatment, and outcome data were recorded. Four dogs met inclusion criteria. One dog had primary spinal MCT and three dogs had metastatic spinal MCT. All four dogs presented for paraspinal hyperesthesia and subacute progressive or acute myelopathy. All CT and MRI lesions were extradural. Two cases exhibited distinct masses in the epidural space. In one case, an epidural tumor invaded from the paravertebral musculature. One case exhibited polyostotic lesions indistinguishable from multiple myeloma by MRI. One dog with a primary epidural low-grade MCT remains clinically normal 4 years postoperatively, following adjunctive lomustine. An epidural high-grade MCT, metastatic from a cutaneous tumor, recurred within 2 months of surgery despite adjunctive vinblastine. Two high-grade cases with concurrent visceral involvement were euthanized immediately after imaging. In dogs, MCT should be considered as a differential diagnosis for a progressive painful myelopathy and CT or MRI evidence of an extradural spinal lesion (epidural, paravertebral, or polyostotic). While more often associated with cutaneous or disseminated disease, MCT may also occur as a primary tumor of the epidural space in dogs.

A pilot study of toceranib/vinblastine therapy for canine transitional cell carcinoma.

BACKGROUND: Effective therapies for transitional cell carcinoma (TCC) are limited, with objective response rates to most chemotherapeutic regimens below 20%. The purpose of this study was to investigate the biologic activity of combined toceranib phosphate and vinblastine chemotherapy for treatment of TCC. A secondary objective was to compare the utility of Computed Tomography (CT) and abdominal ultrasound (AUS) in tumor response assessments. RESULTS: Dogs with TCC received vinblastine at 1.6 mg/m2 every 2 weeks and toceranib at 2.5-2.75 mg/kg on Monday/Wednesday/Friday. Tumor monitoring was achieved through CT and AUS. Five patients completed the 16-week study. Based on AUS assessments, 3 dogs experienced biologic response to therapy including partial responses (PR, n = 2) and stable disease (SD, n = 1). Based on CT, 5 dogs experienced a biologic response (n = 2 PR, n = 3 SD). Both imaging modalities (ultrasound and CT) were found to provide repeatable measurements between operators, however agreement between operator measurements was greater when CT images were used to assess tumor size. CONCLUSIONS: The combination of toceranib and vinblastine did not result in improved response rates. While agreement in tumor volume assessments between both AUS and CT were excellent between operators, this did not extend to assessment of tumor response. The higher rate of concordance between operators when assessing response to treatment with CT suggests that CT should be considered for future clinical trials involving canine bladder TCC to improve the accuracy and repeatability of tumor measurement. The data suggest that response to therapy as assessed by AUS or CT do not predict duration of clinical response.