SPECT-computed tomography in rats with TNBS-induced colitis: A first step toward functional imaging

AIM

To assess the feasibility of SPECT-computed tomography (CT) in rats with trinitrobenzene sulfonic acid (TNBS)-induced acute colitis and confront it with model inflammatory characteristics.

METHODS

Colitis was induced in Sprague-Dawley rats by intrarectal injection of TNBS (n = 10) while controls received vehicle (n = 10). SPECT-CT with intravenous injection of 10 MBq of 67Ga-Citrate was performed at day 2. SPECT-CT criteria were colon wall thickness and maximal wall signal intensity. Laboratory parameters were assessed: colon weight:length ratio, colon cyclooxygenase-2 expression by western blot and histological inflammatory score.

RESULTS

Colon weight/length ratio, colon COX-2 expression and histological inflammatory score were significantly higher in the TNBS group than in the control group (P = 0.0296, P < 0.0001, P = 0.0007 respectively). Pixel max tend to be higher in the TNBS group than in the control group but did not reach statistical significance (P = 0.0662). Maximal thickness is significantly increased in the TNBS group compared to the control group (P = 0.0016) while colon diameter is not (P = 0.1904). Maximal thickness and colon diameter were correlated to colon COX-2 expression (P = 0.0093, P = 0.009 respectively) while pixel max was not (P = 0.22). Maximal thickness was significantly increased when inflammation was histologically observed (P = 0.0043) while pixel max and colon diameter did not (P = 0.2452, P = 0.3541, respectively).

CONCLUSION

SPECT-CT is feasible and easily distinguished control from colitic rats.

Non-osseous uptake on Tc99m methylene diphosphonate in multiple muscles confirmed on SPECT/computed tomography

A 55-year-old female presented with complaints of pain in the left hip radiating to the left lower limb since 1 year. Computed tomography (CT) abdomen and pelvis revealed bony destruction of pubic symphysis with associated soft tissue component suspicious of infective or metastatic etiology. Magnetic resonance imaging Lumbo-sacral spine performed later revealed altered bone marrow signal in sacral 1-3 vertebrae. Wholebody bone scan with 25 mCi of Tc-99m methylene diphosphonate (MDP) was performed, which revealed multiple skeletal metastases and extraosseous soft tissue uptake was seen involving multiple muscles. We performed single photon emission tomography single photon emission computed tomography (SPECT)/computed tomography (CT) images to precisely delineate the muscle involved and noted calcification on CT images in one of the muscle at site of Tc-99m MDP uptake, no definite calcification was noted in the other muscles. Thus, the final diagnosis was multiple skeletal metastasis with metastatic calcification in multiple muscle from an unknown primary.