Evaluation of the Feline Pancreas Using Computed Tomography and Radiolabeled Leukocytes

Abstract

This study was designed to test the feasibility and utility of computed tomography and radiolabeled granulocytes in evaluating the feline pancreas in six normal cats. Autologous granulocytes were labeled with 99mTc-hexamethylpropyleneamine oxime (HMPAO) and injected into each cat. Whole body scintigraphic images were acquired at 1, 5, 15, and 30 minutes, and 1, 2, and 4 hours following injection. The following day, each cat was anesthetized and computed tomographic images of the abdomen were acquired both pre- and post-contrast. Following CT, a surgical pancreatic biopsy was collected. Feline granulocytes were successfully labeled with 99mTc-HMPAO with a labeling efficiency of 15-42% (average of 27%). An average of 5.42 x 10(7) cells in a 2 mL volume were injected into each cat. Less than 1 minute was required to acquire 500,000 count images. Granulocytes distributed predominantly to the lung, spleen and liver in order of decreasing activity. Only background activity was identified in the region of the pancreas. The pancreas was easily identified on CT images of the abdomen. The pancreas was hypoattenuating relative to both the spleen and liver. The pancreas enhanced with the administration of contrast medium, peaking immediately, then gradually clearing over the 30-minute test period. Following contrast medium administration the pancreas remained hypoattenuating relative to the spleen. All biopsies confirmed the absence of pancreatic inflammation in the study cats and no adverse effects were recognized as a result of pancreatic biopsy. Both computed tomography and radiolabeled granulocytes appear to hold promise as imaging procedures for the detection of feline pancreatitis. We predict that these described normal parameters may be altered in the face of inflammation, facilitating detection of feline pancreatitis. Data from cases of suspect feline pancreatitis are needed to evaluate these methods for clinical utility.

Computed tomographic appearance of abdominal lymph nodes in healthy cats

“…Computed tomography (CT) is commonly used in veterinary medicine and plays an important role in disease identification and cancer staging. The CT appearance of several infectious, inflammatory and neoplastic conditions has been described in cats including mycobacterial infections, peritonitis, pancreatitis, mediastinal masses, adipose masses, and fibrosarcoma . Differentiation of normal versus disease‐affected abdominal lymph nodes on CT is important not only for clinical and therapeutic decision making, but also for cancer staging and prognostication.…”

Use of Computed Tomography and Radiolabeled Leukocytes in a Cat With Pancreatitis

“…CT has proven to be the most important imaging modality to evaluate the pancreas in humans 7 . The CT appearance of the normal feline pancreas has been described as homogenous with a smooth undulating margin and parenchyma that is hypoattenuating compared with the spleen and liver 1 . After administration of intravenous iodinated contrast medium, the pancreas becomes uniformly hyperattenuating compared with its precontrast state; this peaks immediately and then gradually declines over 30 min 1 …”

“…The primary sites of distribution in the cat include the lung, liver, spleen, and bone marrow 1 . There is normally a photopenic void in the region of the pancreas 1 …”

“…Nine milliliters of blood was collected from a preexisting jugular vein catheter into a syringe containing 1 ml of anticoagulant citrate dextrose solution * . The granulocytes were separated and labeled with 99m Tc–hexamethylpropyleneamine oxime (HMPAO)† according to an established protocol 1 . Instant thin layer chromatography was utilized to assess radiochemical purity, revealing 87.6% of the 99m Tc bound to HMPAO.…”

Pancreas

“…[1][2][3][4][5][6][7][8][9][10] Fiberoptic technology has enabled the use of endoscopic retrograde cholangiopancreatography and endoscopic ultrasonography for pancreatic evaluation in humans. More recently, computed tomography, magnetic resonance imaging, and scintigraphy have played major roles in assessing pancreatic disease in humans.…”