 Good morning all. I am Dr. Isha Pasari, third-year resident from Department of Radiology, Grand Government Medical College and Sir J.J. Group of Hospitals, Mumbai. I am presenting a paper on CT urography approach towards optimized protocol. Aim of this study was to optimize protocol of computed tomography- urography study by split rulers technique and address on examination. To assess usefulness of correlating address on findings before starting urography study in optimizing the protocol for a patient and to reduce radiation dose given to a patient in CT urography study. CT urography is nowadays routinely used investigation for patients with flank pain and hematuria. The higher diagnostic accuracy for patients examined for suspected urinary tract pathology has justified the shift from excretory urography, which is an X-ray-based procedure to CT urography. CT examinations must be both justified and optimized. Optimization means that a radiologist must reduce the radiation dose from the CT examination as far as possible without losing clinically important information. CT urography helps in assessment of calculated uretric obstruction and excretory function of kidneys. It is an accepted modality for complete and accurate evaluation of urinary tract pathologies. This is a chart representing a generalized protocol of CT urography study. A plane scan is done, followed by contrast administration. After 30 seconds of contrast injection, a cortico medullary phase is taken. After 80 to 100 seconds, a nephrogenic phase is taken. After 8 minutes, an excretory phase is done. And depending on the patient, a delayed phase is taken in 20 minutes. So, total 4 or more number of CT phases are required. Here is an example image. It is showing a plane CT phase showing a hyperdense calculation in figure 1. This is an early cortico medullary CT taken at 30 seconds. Then at 100 seconds, a homogenous nephrogenic phase is done. And then at 8 minutes, excretory phase image is taken showing uretric opacification. This is another image showing how early cortico medullary CT phase taken at 30 seconds shows less enhancement of renal medulla as compared to the homogenous nephrogenic phase showing enhancement of both cortex and medulla of kidney. Hence, religions present in the medulla are well differentiated on nephrogenic phase as shown in this image, an angiomyel apoma in cortex as well as medulla, which are less conspicuously seen in cortico medullary phase images of CT and better seen on nephrogenic images. So, study was done. In all patients coming for CT urography to the department, patients were assessed by taking detailed clinical history and ultrasound examination to decide the protocol for CT urography. Split bolus technique, prone imaging and adequate delayed scans were done as per individual patient finding and study was done on 41 patients coming for CT urography. Here is a chart representing split bolus protocol. In split bolus protocol, a plane scan is done and after that, first bolus of contrast is injected containing 40 ml of contrast. After this, waiting for eight minutes, second bolus of contrast is injected. After second bolus of contrast, similar in a similar fashion, cortico medullary and nephrogenic phases are taken at 30 second and 100 second. However, at the 100 second scan, the nephrogenic phase and excretory phases are combined and there is no need to repeat another scan at eight minutes. Thus, total two or three number of CT phases are required for this method. So, as per ultrasound examination findings, the protocols were decided in patients with no focal lesions of kidneys on ultrasound or just a simple renal cyst on ultrasound. Split bolus method of contrast administration was used and only combined excretory and nephrogenic phases was used. No cortico medullary nephrogenic phase was taken. In case patients with hematuria showing no obvious USG findings, renal vasculature assessment was important. So, in these patients, a cortico medullary nephrogenic phase was done. So, total of two or three phases were taken. This is a representative image, 20-year-old patient with complaint of flank pain. Plane CT revealed a ureteric calculus in right ureter. Contrast was administered by split bolus and in second phase, there was uniform enhancement of renal perinchyma as well as there was complete opacification of both the ureters. Hence, total of two phases were required for complete assessment. In patients with focal lesion cell kidney showing complex cysts or lesions, a cortico medullary phase was also done apart from combined nephrogenic and excretory phase. Thus, a total of three phases were required. In patients with renal neoplasm or those patients who were planned for operative intervention or there was a need for arterial anatomy evaluation, single bolus contrast injection was given and a plane CT arterial and nephrogenic phases were taken and excretory phase was done. Hence, total of four or more phases were required as shown in this image. Figure one is showing a plane CT, showing a lobulated mass in left kidney. Figure two is showing enhancing mass in left kidney and it is showing well contrast to pacification of abdominal aorta. Figure three is nephrogenic phase showing uniform enhancement of renal perinchyma. However, the left kidney is not showing well enhancement in the renal medulla. Figure four is showing a delayed phase taken at 20 minutes. It is showing excretion of contrast material into renal pelvis in right kidney, which is not so in left kidney showing poor excretory function of left kidney. So, a total of five phases were done using two delayed scans apart from cortico medullary and nephrogenic phase. Contrast material typically appears in the renal collecting system three minutes after the start of bolus IV contrast. So, intrarenal collecting system and ureters are well distributed by 8 to 10 minutes. Ureters are well visualized on 10 minute image and bladder is best seen on 20 minute images. Delayed scans are needed to look for ureteric pacification. It is needed in diagnosing stretchers and filling defects. However, additional excretory delayed phase imaging may not be necessary for sole purpose of ruling out a tumor in a partially unopacified but otherwise normal ureter. That is, if there is no hydronephrosis, ureteral thickening or perioriteral stranding, there is no use for delayed scan as the risk of radiation exposure is more as compared to benefit. Here is another case, a 42 year old female complaining of urine leak per vagina since one and a half month post-historic tummy status. Figure one is depicting a plain CT showing hydronephrosis in right kidney with entire hydroneurator. After a split bolus administration of contrast, a combined nephrogenic excretory phase was done. Both combined nephrogenic excretory phase as well as 20 minute delayed phases showed that right ureter was not well opacified. So, another delayed scan was done at 40 minute in prone position which shows opacification of entire right ureter as well as left ureter. There was abrupt narrowing of right ureter at the junction vascoeuritric junction suggestive of stretcher. Also, there was a faint line of contrast tracking from right ureter into the vagina suggestive of a ureter vaginal fistula. After this study, there were only four patients who came with hematuria and 33 patients came with complain of flank pain. There were eight patients with other relevant complaints like chyluria, urine leak per vagina, blunt trauma followed by hematuria and urinary retention. Out of these patients, 28 patients were diagnosed with renal or ureteric calculae who were examined with split bolus method with plain and combined nephrogenic excretory phase. Thus, only two CT phases were required. Only two patients had angiomyolipoma which which were examined by three phases consisting of plain cortico medullary and combined nephrogenic excretory phase. There were two patients with renal malignancy or bladder malignancy who were examined with single bolus administration of contrast with plain cortico medullary, nephrogenic and excretory phase and there were few other patients with renal tuberculosis or prostatomegaly or cystitis who were examined by split bolus technique with adequate delayed scan. Thus, total of three to four phases were needed. One patient had a renal laceration. Patient had history of trauma followed by hematuria. For this patient, CT was done with triple face abdomen CT followed by a delayed scan of eight minute and one patient had a normal study with no abnormality detected.