Optiray 350

MRI was performed on the same 3.0 T Siemens scanner (Erlangen, Germany). The parameters of MR examination were as follows: axial T2-weighted (repetition time, 4500 ms; echo time, 93 ms), axial T1-weighted imaging (repetition time, 2000 ms; echo time, 9.2 ms), axial diffusion-weighted imaging (repetition time, 3300 ms; echo time, 91 ms), and coronal fluid-attenuated inversion recovery sequences (repetition time, 8000 ms; echo time, 86 ms).
CTA was performed on a dual-source CT scanner (Somatom Definition; Siemens Medical Solutions, Forchheim, Germany). For head and neck CTA, 70–80 ml non-ionic contrast agent (350 mg iodine/ml ioversol, Optiray 350, Mallinckrodt Pharmaceuticals) was injected into the antecubital vein at 5 ml/s followed by a 40-ml saline flush also at 5 ml/s. The CTA covered the area from just below the aortic arch to the vertex. CTA was performed in a helical scan mode using the following parameters: 64 × 0.6 collimation, 0.65 pitch, 120 kV, automatic exposure control with standard deviation of 10 and exposure range 100–700 mA, 0.625 mm and 3.0 mm slice thickness, 0.33 s rotation time, reconstruction filter FC43 and standard AIDR3D. The bolus tracker was set at an absolute threshold of 180 HU at the level of the descending aorta in dual energy mode.

CT images were acquired on a helical 64-slice CT scanner (Toshiba Aquilion 64 CFX, Toshiba Medical Systems, Tustin, CA). CT scans were performed with animal patients in radiation therapy planning position, which was determined by the radiation oncologist and dependent on the tumor location and geared towards maximizing the reproducibility of repeated setup. All examinations consisted of reconstructed 2- or 3-mm-thick transverse images. Intravenous contrast medium (770 mg or I/kg; Optiray 350 [Ioversol], Mallinckrodt Inc, Hazelwood, MO) was administered to all animals following acquisition of pre-contrast data. Non contrast- and contrast-enhanced CT studies of the tumor region were retrieved from a PACS workstation in DICOM file format and sent to a computer utilizing commercially available contouring software (MIM Maestro 6.12, MIM Software Inc., Cleveland OH). Prior to radiation therapy, contours were manually drawn by the radiation oncologist that outlined regions of interest (ROI), tumor / target volumes and any nearby critical normal structures (segmentation). For tumors in the skin/subcutaneous tissue, bolus was created and retracted from the skin edge by 1 mm. Image sets with RT structure sets were subsequently sent from MIM to the treatment planning station (Pinnacle³, Philips Oncology Systems, Fitchburg, WI).

WBCT exams were carried out using multi-slice CT systems (Somatom Sensation 4 or 16, Siemens Medical Systems, Erlangen, Germany) if clinically suspected recurrence was indicated during the follow-up. Contiguous axial sections (0.5-cm thickness) were scanned in a craniocaudal direction between the lower neck and the pelvis, about 60–70 s following intravenous injection of 100 mL of iodinated contrast medium (Omnipaque 350, Amersham (Cork, Ireland)) or Optiray 350, Mallinckrodt (St. Louis, MO, USA)), at a rate of 2–3 mL/s. Routine coronal reconstruction was done for all CT studies. Two radiologists (G.L. and P.C.H.) reviewed the CT scans for all patients. Ovarian lesions were classified based on the morphology features (solid, solid-cystic or cystic) and laterality (unilateral or bilateral). The solid lesion was defined by lesions with predominant soft tissue densities with any degree of enhancement on CT. Lesions exhibiting both solid and bilateral patterns were defined as having a combined feature.