Multi-Detector row CT urography on a 16-row CT scanner in the ...

is small, we successfully detected seven (100%) of seven
foci of upper tract malignancies and nine (90%) of 10
urinary bladder malignancies, including seven tumors with
a diameter equal or smaller than 0.5 cm. MD<strong>CT</strong>U has
demonstrated satisfactory results in the detection of
uroepithelial malignancies [5, 13, 15, 25]. Caoili et al. [5]
detected 15 out of 16 foci of TCCs, including one lesion of
5 mm in maximal diameter. The same group of
investigators [15] retrospectively reviewing 370 MD<strong>CT</strong>
<strong>urography</strong> examinations of patients suspected of urinary
tract disease, identified 24 of 27 upper tract cancers,
including five masses with a diameter equal or smaller than
5 mm. In another series, McCarthy and Cowan [25]
performing MD<strong>CT</strong>U and retrograde pyelography in 106
high-risk patients correctly identified all upper tract
malignancies, with MD<strong>CT</strong>U proving more sensitive than
retrograde pyelography (sensitivity: 98% versus 79%). In
the same study only one bladder cancer was not detected.
In another multi-institutional study [13] of 350 patients
with hematuria four patients had bladder TCCs, one had an
urachal adenocarcinoma and only one patient had TCC of
the upper tact, all detected on MD<strong>CT</strong>U. The above groups
of investigators used either a 4- or an 8-detector <strong>row</strong> <strong>CT</strong>
scanner. Our study demonstrated that 16-<strong>row</strong> <strong>CT</strong> <strong>urography</strong>
could detect uroepithelial malignancies, including
lesions of small size, even though a larger number of
patients are needed to support the above data. The
satisfactory results of 16-<strong>row</strong> <strong>CT</strong> <strong>urography</strong> in the
detection of urinary bladder neoplasms in this study,
perhaps they would obviate the need of performing
conventional cystoscopy in patients presenting with hematuria
and positive results on MD<strong>CT</strong> <strong>urography</strong>.
Of major concern with <strong>CT</strong> <strong>urography</strong>, as well as with
IVU, is the necessity for complete distention and opacification
of the renal collecting systems and ureters. There is
always a theoretical possibility that small urothelial lesions
located in these unopacified segments could be missed.
Other investigators, however, believe that the necessity for
ureteral distention is simply a radiological myth and that
urothelial neoplasms are manifested at imaging as filling
defects or obstruction and not as underfilling of the uretes
[4]. Even in cases of non-complete distention and opacification
of the uretes the evaluation of the unopacified
segments on axial images may be satisfactory [3]. The high
negative predictive value (100%) of the non-opacified
ureter for the presence of uroepithelial malignancies, as
showed in this study, perhaps justifies the above statement.
As with other multiphasic abdominal <strong>CT</strong> protocols, <strong>CT</strong>
<strong>urography</strong> exposes the patient to increased radiation
exposure, which has to be weighted against the expected
benefit from the examination. We estimated an effective
dose of 29 mSv is required for our entire protocol
(11.1 mSv for the unenhanced scan, 5.9 mSv for the
nephrographic phase, 11.3 mSv for the excretory phase and
1 mSv for PSPR). This value is within the range of 25–
35 mSv for an average size male, given by Caoili et al. [5],
for a four-phase protocol, on a 4-detector <strong>row</strong> <strong>CT</strong> scanner.
The same group of investigators found that MD<strong>CT</strong>U
exposure for the same protocol was similar to the radiation
exposure resulting from the combination of IVU and
conventional single-phase <strong>CT</strong> examination. McTavish et al.
[26] reported a total effective dose of 22.6 mGy, using a
three-phase protocol, on a 4-detector <strong>row</strong> <strong>CT</strong> scanner. Skin
dose should be also taken into account. In the present study
the mean skin dose of 58 mGy was similar to the 54.6 mGy
mean dose reported by Nawfel et al. [27] and lower than
that of 74.1 mGy reported by McTavish et al. [26].
In conclusion, multidetector <strong>row</strong> <strong>CT</strong> <strong>urography</strong> on a 16-
<strong>row</strong> <strong>CT</strong> scanner demonstrated satisfactory results in the
investigation of painless hematuria, being able to demonstrate
a wide spectrum of diseases affecting the urinary
tract. An important advantage of the technique was its
ability to detect uroepithelial malignancies, although a
larger series is needed to confirm the effectiveness of 16-
<strong>row</strong> <strong>CT</strong>U in the detection of small-sized tumors.
References
1. Noroozian M, Cohan RH, Caoli EM,
Cowan NC, Ellis JH (2004) <strong>Multi</strong>slice
<strong>CT</strong> <strong>urography</strong>: state of the art. Br J Rad
77:S74–S86
2. Kawashima A, Vrtiska TJ, Hartman RP,
McCollough CH, King BF (2004) <strong>CT</strong>
<strong>urography</strong>. Radiographics 24:S35–S54
3. Joffe SA, Servaes S, Okon S, Ho<strong>row</strong>itz
M (2003) <strong>Multi</strong>-detector <strong>row</strong> <strong>CT</strong> <strong>urography</strong>
in the evaluation of hematuria.
Radiographics 23:1441–1455
4. Coakley FV, Yeh BM (2003) Invited
commentary. Radiographics 23:1455–
1456
5. Caoli EM, Cohan RH, Korobkin M,
Platt J, Francis I, Faerber G, Montie J,
Ellis J (2002) Urinary tract abnormalities:
initial experience with multi-detector
<strong>row</strong> <strong>CT</strong> <strong>urography</strong>. Radiology
222:353–360
6. Smith RC, Rosenfield AT, Choe KA,
Essenmacher KR, Verga M, Clickman
MG, Lange RC (1995) Acute flank
pain: comparison of non-contrast enhanced
<strong>CT</strong> and intravenous <strong>urography</strong>.
Radiology 194:789–794
7. Wang LJ, Ng CJ, Chen JC, Chiu TF,
Wong YC (2004). Diagnosis of acute
flank ain caused by ureteral stones:
value of combined direct and indirect
signs on IVU and unenhanced helical
<strong>CT</strong>. Eur Rad 14:1634–1640
8. Sheth S, Scatarige JC, Horton KM,
Corl FM, Fishman EK (2001) Current
concepts in the diagnosis and management
of renal cell carcinoma: role of
multidetector <strong>CT</strong> and three-dimensional
<strong>CT</strong>. Radiographics 21:S237–S254