It depends on amount of the contrast material used. The codes for high osmolar contrast are as follows:
Q9958 High osmolar contrast material, up to 149 mg/ml iodine concentration, per ml
Q9959 High osmolar contrast material 150-199 mg/ml iodine concentration, per ml
Q9960 High osmolar contrast material 200-249 mg/ml iodine concentration, per ml
Q9961 High osmolar contrast material 250-299 mg/ml iodine concentration, per ml
Q9962 High osmolar contrast material 300-349 mg/ml iodine concentration, per ml
Q9963 High osmolar contrast material 350-399 mg/ml iodine concentration, per ml
Q9964 High osmolar contrast material 400 or greater mg/ml iodine concentration, per ml
Q9965 Low osmolar contrast material, 100-199 mg/ml iodine concentration, per ml
I notice you also have this question in the radiology forum so I hope this is helpful.