ULTRASONOGRAPHIC EVALUATION OF A TRAUMATIC SPLENIC HEMATOMA AND LITERATURE REVIEW

Triple-phase helical computed tomography in dogs with solid splenic masses

We investigated the utility of triple-phase helical computed tomography (CT) in differentiating between benign and malignant splenic masses in dogs. Forty-two dogs with primary splenic masses underwent triple-phase helical CT scanning (before administration of contrast, and in the arterial phase, portal venous phase, and delayed phase) prior to splenectomy. Tissue specimens were sent for pathological diagnosis; these included hematomas (n=14), nodular hyperplasias (n=12), hemangiosarcomas (n=11), and undifferentiated sarcomas (n=5). The CT findings were compared with the histological findings. Nodular hyperplasia significantly displayed a homogeneous normal enhancement pattern in all phases. Hemangiosarcoma displayed 2 significant contrast-enhancement patterns, including a homogeneous pattern of poor enhancement in all phases, and a heterogeneous remarkable enhancement pattern in the arterial and portal venous phases. Hematoma and undifferentiated sarcoma displayed a heterogeneous normal enhancement pattern in all phases. The contrast-enhanced volumetric ratios of hematoma tended to be greater than those of undifferentiated sarcoma. Our study demonstrated that the characteristic findings on triple-phase helical CT could be useful for the preoperative differentiation of hematoma, nodular hyperplasia, hemangiosarcoma, and undifferentiated sarcoma in dogs. Triple-phase helical CT may be a useful diagnostic tool in dogs with splenic masses.

THE HILAR PERIVENOUS HYPERECHOIC TRIANGLE AS A SIGN OF ACUTE SPLENIC TORSION IN DOGS

Diagnosis of acute primary splenic torsion is challenging. The ultrasonographic appearance of this condition has been described, but other splenic diseases, such as diffuse infarction because of thrombosis, can appear very similar. We describe an additional ultrasonographic sign of acute splenic torsion; a triangular hyperechoic area at the hilus between the veins and the splenic parenchyma that is continuous with the hyperechoic mesentery. In a group of animals where acute splenic torsion was part of the ultrasound report differential diagnosis, we compared findings in dogs with torsion with findings in dogs with other splenic conditions. The presence of a hilar hyperechoic perivenous triangle was significantly associated with splenic torsion (P = 0.005). We speculate that this sign is associated with torsion because of the secondary severe, diffuse splenic enlargement. Although not pathognomonic, this sign could be used to more accurately diagnose splenic torsion in light of other findings consistent with this condition.

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

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.

Traumatic subcutaneous translocation of the spleen in an Old English sheepdog

A 14-month-old entire male Old English sheepdog was presented with a slowly enlarging subcutaneous soft tissue swelling caudal to the last rib. Radiographic and ultrasonographic Investigations demonstrated a soft tissue mass closely adherent to the body wall, with a coarse hypoechoic pattern. Surgical exploration revealed a mass with the gross appearance of splenic tissue. The mass was adhered to a healed paracostal abdominal tear. Histological examination confirmed the resected tissue to be normal spleen.

Ultrasonography of abdominal cavitary parenchymal lesions

Cavitary parenchymal lesions are composed of varying amounts of soft tissue, fluid, and/or gas. These cavitary lesions are focal or multifocal and therefore readily detected ultrasonographically. The ultrasonographic appearance of cystic and noncystic cavitary lesions are described. Differential diagnoses for these cavitary lesions in abdominal organs are listed.