Thursday, 15 September 2016

Twisted Fat Stranding in a Dog with Isolated Splenic Torsion Diagnosed with Computed Tomography

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A 7- year- old, male canine was referred with apathy and anorexia from last four days. Radiography revealed splenomegaly and ultrasound showed a “lacy parenchyma” with “hyperechoic perivenous” triangle. A tentative diagnosis of splenic torsion was made. The CT examination was performed for special reconstructions and to obtain additional information to confirm the diagnosis. Images in an oblique plane transversal to the splenic arteries and veins were reconstructed. Looking at these images in a fast forward video mode, the rotated pedicle, containing the splenic vessels along the gastrosplenic ligament, surrounded by the twisted, striated, hyperattenuating fat had a striking resemblance to a meteorological satellite video of a tornado. The “Tornado sign” is a characteristic, possibly pathognomonic sign of splenic torsion. Splenic torsion was than confirmed on exploratory laparotomy. The dog recovered completely with supportive care. In conclusion, if torsion of an organ is suspected and computed tomographic images in standard planes fail to demonstrate and identify the rotation, images perpendicular to the pedicle and/or main mesenteric or hilar vessels supplying the organ should be reconstructed and evaluated in a fast forward video mode as an additional diagnostic tool.

Isolated Splenic Torsion is a rare condition in dogs with unspecific clinical signs. The Great Dane and German Shepherd dogs are found to be at increased risk for isolated splenic torsion. No age or sex predilection is known. For diagnosing splenic torsion radiographic and ultrasound examinations are further strongly recommended diagnostic tests, but none is necessarily pathognomonic. Laparotomy is the gold standard to confirm splenic torsion. With CT examination and special reconstructions additional information is obtained to confirm the tentative diagnosis of splenic torsion before surgery.A 7- year- old, male Hovawart was referred with apathy and anorexia from last four days. The dog was treated with antibiotics (Doxycyclin, Streptomycin, Metamizol) by the local veterinarian without any improvement. Upon the presentation at the clinic, the dog was alert, mildly dehydrated (< 5%), exhibited increased rectal temperature of 39.5°C and heart rate of 100 bpm. A mass was palpated in the mid-abdomen. While the abdomen was examined, the dog was painful. The remaining physical examination findings were within normal limits. Complete blood examination was carried out.

Complete blood count revealed elevated leucocytes (19+109 /l), decreased hematocrit (31%) and increased ALT (407 U/L), AP (1122 U/l) and Bilirubin (8,8 µmol/l). The right lateral and ventrodorsal abdominal radiographs of the spleen revealed enlarged spleen with round margins. The dorsal extremity of the spleen, normally situated in the left hypogastric region, was displaced to the right side. The ventral extremity extended to the level of the fourth lumbar vertebra in the midventral line. No gas accumulations were seen within the spleen.

Abdominal CT examination was performed with a 64-slice, helical CT scanner (Somatom Definition AS, Siemens Healthcare, Erlangen, Germany). The dog was placed in sternal recumbency under general inhalation anesthesia. Breath hold technique in exspiration was used to minimize motion artifacts. Transverse images of the abdomen were acquired using 64x 0.6-mm detector collimation, 120 KVp, 120 mA, 1sec rotation time and 512x512 reconstructed image matrix. A soft tissue algorithm (B26f) was used for reconstruction. Further, a dualphase post contrast study was done, using 600 mg iodine per kg BW intravenous contrast agent (Iohexol, Accupaque 300, GE Healthcare Buchler GmbH&Co. KG, Braunschwaig, Germany) administered via power injector at a rate of 2.9 ml/ sec in the cephalic vein (total contrast dose 68.1 ml; 22.9 sec contrast flow duration). A region of interest was placed in the aorta at the level of the cardiophrenic angle, and the arterial scan was started with a delay of 5 seconds after a peak of 100 Hounsfield Units (HU) in the descending thoracic aorta. The late phase was started with a delay of 43 seconds after a peak of 100 HU in the descending thoracic aorta. 

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