DESCRIPTOR

ADEQUACY OF MODIFIED CT UROGRAM TECHNIQUE AND ITS IMPACT ON THE OPACIFICATION OF URINARY TRACT.

SALMAN ATIQ SIDDIQUI & NIALL MACKENZIEDEPARTMENT OF MEDICAL IMAGING, ALTNAGELVIN HOSPITAL, WHSCT, LONDONDERRY, NORTHERN IRELAND

Scoring based assessment of adequate urinary tractopacification in CT urogram (CTU).

Various CTU techniques have been described, i.e. singleor split bolus protocol1, 2. Over the past decade,modifications have led to improved urinary tractvisualization3. In excretory-phase CT, distal ureter is themost difficult segment to opacify4.

INITIAL RESULTS AND RECOMMENDATIONS:Mean scores were significantly below the expectedtarget (table 2). Particular problem seemed to be hold upat the level of psoas muscle. Additionally, the layeredopcification raised the false impression of intrinsic lesion

Table 1: Simplified scoring system for the opacification of pelvicalyceal system and ureters in CTU.

BACKGROUND

THE STANDARDNo nationally agreed standard is available.

PELVICALYCEAL SYSTEM (PC) URETERS (U) TOTALPoor/ non-opacification = 0 No or <1/3 opacification = 0 0+0=0Partial/ layered opacification = 1 >1/3 but <2/3 opacification = 1 1+1=2Good opacification (renal pelvis+/- calyces) = 2 >2/3 but not complete opacification = 2 2+2=4Good opacification (renal pelvis+calyces/ infundibula) = 3 Complete opacification = 3 3+3=6

RESULTSIn re-audit, 62 patients were male and 38 were femalewith the mean age of 61.9 years (range 18-90 years).Following are the comparative results of initial and re-audit (table 2).

Fig 2: Axial images of right kidney in prone excretory phase CTU showing (a) layered pattern of opacification [red arrows] and (b) its

rectification by roll over technique.

2.5

3

3.5

2

2.5

3

PELV

ICAL

CYCE

AL S

YSTE

M

PELV

ICAL

CYCE

AL S

YSTE

M

a b

CONCLUSION

opcification raised the false impression of intrinsic lesion(image 1). Re-audit with modified technique wasrecommended.

To achieve an overall average of 90% (score of 5.4/6 forpelvicalyceal and ureteric opacification cumulatively) toguarantee good opacification bilaterally.

Modified split bolus CTU technique has improvedurinary tract opacification. Also, locally designed scoringis an effective tool for systematic assessment of CTU.quality.

INITIAL AUDIT

TARGET

No nationally agreed standard is available.We followed our locally agreed triple bolus protocol ofCTU in the initial audit:Prone NECT KUB followed by first contrast bolus of 40mL, second contrast bolus of 30 mL at 7 mins 15 secs, &final contrast bolus of 70 mL at 8 mins 8 secs thenacquisition of CECT at 8 mins 30 sec. Locally designedscoring system was used to assess the urinary tractopacification (table 1).

INITIAL AUDIT RE-AUDIT Patients ≤60 years (n=23)oMean Total Score: 4.9oMean PC Score: 2.8oMean Ureter Score: 2.1

Patients ≤60 years (n=33)oMean Total Score: 5.1oMean PC Score: 2.7oMean Ureter Score: 2.3

Patients >60 years (n=29)oMean Total Score: 3.6oMean PC Score: 2.0oMean Ureter Score: 1.6

Patients >60 years (n=67)oMean Total Score: 5.3oMean PC Score: 2.8oMean Ureter Score: 2.5

Fig 1: Axial (a) & coronal (b) images of right kidney in prone excretory phase CTU showing layered pattern of opacification

(yellow arrows), misleading for a false positive intrinsic urotheliallesion.

RE-LOOP AUDIT

audit (table 2).

METHOD: Consecutive 52 CTU with pre-existingdepartmental protocol performed on 128 slice Siemensscanner were included. There were 24 females & 28males with mean age 64.9 years (range 34-87 years).

METHOD: Consecutive 100 CTU with modified CTUprotocol performed as follows:After first contrast bolus of 40 mL, the patients were‘Rolled over’ 360 degrees on table at 3.5 mins after the1st bolus. Rest of the protocol remained as before.

Further scrutinizing and excluding 16 supine CTU in re-audit (table 3), the target of 90% was achieved (totalscore of 5.4).

Table 2: Comparative results of initial with re-audit.

PRONE PATIENT POSITION SUPINE PATIENT POSITION N = 84oMean total score: 5.4oMean PC score: 2.9oMean Ureter score: 2.5

N = 16oMean total score: 4.7oMean PC score: 2.6oMean Ureter score: 2.1

Table 3: Comparative results of re-audit in prone and supine CTU.

0

0.5

1

1.5

2

2.5

0 1 2 3 4

0

0.5

1

1.5

2

0 1 2 3

PELV

ICAL

CYCE

AL S

YSTE

M

PELV

ICAL

CYCE

AL S

YSTE

M

URETER(INITIAL AUDIT)

URETER(RE-AUDIT)

Scattered graph showing stronger positive correlation between the pelvicalyceal system and ureteric opacification in CTU.

REFERENCES1. RCR iRefer: Making the best use of clinical radiology. Seventh Edition 2012. ISBN: 978-1-

905034-55-0.2. Van Der Molen AJ, Cowan NC, Mueller-Lisse UG et al (2008). CT urography: definition,

indications and techniques. A guideline for clinical practice. Eur Radiol 18: 4-17.3. Washburn, Z., Dillman, J., Cohan, R., Caoili, E. and Ellis, J. (2009). Computed Tomographic

Urography Update: An Evolving Urinary Tract Imaging Modality. Seminars in Ultrasound, CTand MRI, 30(4), pp.233-245.

4. Kawamoto S, Horton KM, Fishman EK (2006). Opacification of the Collecting System andUreters on Excretory Phase CT using Oral Water as Contrast Medium. AJR 186: 136-140.

a b