Comparison Between Malignant and Nonmalignant Splenic Masses in Dogs using Contrast‐Enhanced Computed Tomography

Abstract

The ability of computed tomography (CT) to distinguish malignant from nonmalignant splenic masses was evaluated in 21 dogs with 24 masses. CT scans of the abdomen were performed pre- and postintravenous contrast medium administration before splenectomy or euthanasia. Splenic masses were evaluated objectively based on Hounsfield units (HU) and volume. Subjective criteria included location within the spleen (head, body, or tail), margination, homogeneity, and attenuation compared to the remaining splenic parenchyma. Characteristics of malignant and nonmalignant masses were compared. The nonmalignant masses were divided into splenic hematomas and nodular hyperplasia for further analysis. Fourteen (58.3%) of the masses were nonmalignant; 10 (41.7%) were malignant. Malignant splenic masses had significantly lower attenuation values, measured in HU, than nonmalignant splenic masses, on both pre- and postcontrast images (P<0.05). On postcontrast images, there was a significant difference in attenuation characteristics among all three subsets of splenic masses (malignant, hematoma, hyperplasia), with nodular hyperplasia having the highest HU values (90.3), hematomas having intermediate HU values (62.5), and malignant splenic masses having the lowest HU values (40.1). A receiver operator characteristic curve of postcontrast medium HU values revealed 55 as the best threshold value to distinguish malignant from nonmalignant masses, with those less than the threshold value being malignant. Abdominal CT is a useful diagnostic imaging modality for evaluation of focal canine splenic masses, with a significant difference in imaging characteristics between malignant and nonmalignant masses.

Contrast-Enhanced Ultrasonography for Characterization of Focal Splenic Lesions in Dogs

“…Among them, hemangiosarcoma showed characteristic hypoechoic pattern during the early vascular phase. This finding concurred with those for sulphur hexafluoride microbubbles‐enhanced ultrasonography 5,6 and contrast‐enhanced computed tomography 21 . This hypoechoic area may correspond to the hemorrhagic or necrotic areas commonly associated with hemangiosarcoma.…”

Imaging in Oncology

“…9 CT is also useful to determine the origin and extent of abdominal mass lesions, and compared to ultrasonography, CT can better document the relationship of a mass with surrounding anatomic structures (Figure 6-5). 18,19 Infiltrative muscular lesions such as infiltrative lipomas and soft tissue sarcomas are routinely imaged with CT for both surgical and radiotherapy planning. 12,20 A contrast-enhanced scan is essential during CT to improve visualization of tumor margins, especially for infiltrative tumors such as feline vaccine-associated sarcomas.…”

“…116 FLT scan of a dog with a nasal adenocarcinoma. 18 F-sodium fluoride ( 18 F-NaF) is a PET tracer that is now commercially available for bone scans. 99,116 Hypoxic radiotracers include several in the nitroimidazole class, including 18 F-misonidazole, the more hydrophilic 18 F-fluoroazomycin (FAZA), and the more lipophilic version 2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3pentafluoropropyl)acetamide ( 18 F-EF5).…”

“…PET radiotracers for noninvasive imaging of tumor hypoxia have been found in human cancer trials to have value in prognostication, predicting response, and better defining hypoxic tumor volumes for boost radiation therapy. 18 F-NaF localizes to areas of high bone turnover similar to 99m Tc-MDP that is used for bone scintigraphy. 60 Cu-labeled diacetyl-bis(N 4methylthiosemicarbazone ( 60 Cu-ATSM) is a non-nitroimidazole tracer that is also being evaluated as a hypoxic tracer.…”

“…16 A,18 F-sodium fluoride ( 18 F-NaF) PET bone scan 3D maximum intensity projection (MIP) image of a dog with a proximal humeral osteosarcoma (black arrow) 6-months poststereotactic radiation therapy. Note the excellent skeletal image with multifocal uptake at the costochondral junctions, the injection catheter, the opposite shoulder joint, and the urinary bladder due to excretion.…”