Comparison of MR imaging and P-31 MR spectroscopy in a rat model of testicular torsion

This paper reports the value of MR imaging (with and without contrast enhancement) and P-31 MR spectroscopy in the diagnosis of testicular torsion assessed in six Sprague Dawley rats. MR imaging 2 T; GE CSI-II; spin echo (SE) 310/15 [repetition time msec/echo time msec] [two excitations] or SE 2,800/100 [four excitations]; field of view, 81 mm; 3-mm sections; 128 x 256 image matrix; Gd-DTPA, 0.2 mmol/kg; iron-dextran, 56 mg/kg and P-31 Mr spectroscopy (surface coils; pulse width, 10 mg/sec; interpulse delay, 2 seconds; 500 acquisitions) were obtained before, 1 hour after 720 degrees torsion, and 1 week after detorsion. In the immediate posttorsion period, both noncontrast and contrast-enhanced MR images failed to demonstrate any abnormalities. P-31 MR spectroscopy as early as 5 minutes after torsion demonstration a significant decrease of the adenosine triphosphate (ATP) peaks with a concomitant large increase of inorganic phosphate (Pi). One week later, T2-weighted images showed a decreased signal intensity (SI) of the torsed testis in four of six animals and a normal SI in the remaining two