ISSN: 0975-8585

Research Journal of Pharmaceutical, Biological and Chemical

Sciences

Role of Computed Tomography in the Evaluation of Urolithiasis.

Shiv Shankar Prasad1*, Shubhda Sagar2, Shiv Kailash Yadav2, Arun Gupta1, and
Mukta Mital2.
1Department of Radiodiagnosis & Imaging, B.P. Koirala Institute of Health Sciences, Dharan, Nepal.
2Department of Radio-Diagnosis & Imaging, N.S.C.B. Subharti Medical College, Meerut, India.

ABSTRACT

Urolithiasis refers to stones originating anywhere in the urinary system, including the kidneys,
ureters and bladder. Radiological Imaging enables not only the diagnosis of urinary tract calculi, but also
the characterization of stones, planning and stratification of further treatment and prediction of response
to such treatment. Computed tomography-KUB (CT-KUB) is now accepted as the gold standard imaging
modality for urinary tract calculi because of its high diagnostic accuracy. This study evaluated the efficiency
and reliability of CT scan for the diagnosis of urolithiasis in the patients with flank pain prospectively. Fifty
patients with radiologically diagnosed Urolithiasis were included in this study. CT imaging was performed
with 128 slice Philips ingenuity CT scanner. In this study it was observed that the most common side
affected for urinary tract stone was right (40%) followed by left side (30%) and bilateral (30%). Most of
the patients had unilateral stones (70%) followed by bilateral (30%). In the present study, it was observed
that nephrolithiasis (56%) and ureterolithiasis (28%) were the most common in patients with urolithiasis.
Our result confirms the significant role of non-contrast computed tomography scan in evaluating
Urolithiasis. From the results, it has been concluded that the CT-KUB is the gold standard investigation for
the diagnosis of urinary tract stones.
Keywords: tomography, urolithiasis, CT-KUB, urinary stones.

https://doi.org/10.33887/rjpbcs/2023.14.1.13

*Corresponding author

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INTRODUCTION

Kidney stone disease, also known as urolithiasis, is the condition when a solid piece of
material develops in the urinary tract. It is an increasing urological disorder of human health, affecting
about 12% of the world population [1]. A small stone may pass without causing symptoms. If a stone grows
to more than 5 millimeters, it can cause blockage of the ureter resulting in severe pain in the lower back or
abdomen. About half of people will have another stone within ten years [2]. Stones form in the kidney
when minerals in urine are at high concentration. The diagnosis is usually based on symptoms, urine
testing, and medical imaging. Blood tests may also be useful. Stones are typically classified by their
location: nephrolithiasis (in the kidney), ureterolithiasis (in the ureter), cystolithiasis (in the bladder), or
by what they are made of (calcium oxalate, uric acid, struvite, cystine) [3].

Urolithiasis refers to stones originating anywhere in the urinary system, including the kidneys,
ureters and bladder [3]. Nephrolithiasis refers to the presence of such stones in the kidneys. Calyceal calculi
are aggregations in either the minor or major calyx, parts of the kidney that pass urine into the ureter [3].
The condition is called ureterolithiasis when a calculus is located in the ureter. Solid calculi which are
primarily found in the urinary bladder are called bladder stones [4]. Stones less than 5 mm in diameter pass
spontaneously in up to 98% of cases, while those measuring 5 to 10 mm in diameter pass spontaneously in
less than 53% of cases [5]. Stones that are large enough to fill out the renal calyces are called staghorn
stones, and are composed of struvite in a vast majority of cases, which forms only in the presence of urease-
forming bacteria.

Various laboratory examinations can be performed for the diagnosis of renal stones. Microscopic
examination of the urine, which may show red blood cells, bacteria, leukocytes, urinary casts, and crystals
are performed routinely. Urine culture are occasionally required to identify any infecting organisms
present in the urinary tract and sensitivity to determine the susceptibility of these organisms to specific
antibiotics. Complete blood count, renal function tests, 24 hour urine collection are some other
investigations which can be performed for the diagnosis of renal calculus. Radiological imaging of kidney
stone is an important diagnostic tool and initial step in deciding which therapeutic options to use for the
management of kidney stones [6]. For the diagnosis of urinary tract stones, a variety of imaging modalities
are available to the practicing urologist, including conventional radiography (KUB), intravenous urography
(IVU), ultrasound (US), magnetic resonance urography, and computed tomography (CT) scans, each with
its advantages and limitations. [7]. Accurate imaging is of the utmost importance in the diagnosis of urinary
calculi.

The kidneys/ureters/bladder (KUB) radiograph is considered most useful in the follow-up of

previously detected radio-opaque calculi and in planning and assessing the effects of therapeutic
interventions [6]. Intravenous urography (IVU) has largely been superseded by Computed tomography-
KUB (CT-KUB) in recent years, as the latter has a higher sensitivity [8]. Ultrasound plays an important role
in diagnosing urinary tract calculi. It is a safe and readily available imaging technique, but its sensitivity is
modest and hugely dependent on the operator and the body habitus of the patient. The advantage of
ultrasound relates to its relative portability and lack of non-ionizing radiation [9].

CT-KUB is now the accepted gold standard imaging modality for urinary tract calculi as a result of
its high diagnostic accuracy [10]. Most stones will be visible on unenhanced CT with a sensitivity of 95 per
cent in the diagnosis of acute ureteric colic. Jaiswal et al. evaluated the use of CT KUB in suspected
urolithiasis in the patients with severe flank pain where they demonstrated the CT KUB as the gold standard
[11]. CT-KUB allows for rapid diagnosis of renal calculi and has been adopted in many centers as a first-
line imaging strategy for renal stones because of its unparalleled ability in diagnosis of ureteric calculi [6].
The presence of hydronephrosis and other signs of urinary tract obstruction can also be elucidated from
CT-KUB, and accurate measurements of stone size can be undertaken [6]. CT-KUB allows for 3-D
reconstructions of data and is especially useful in planning PCNL procedures. Plain CT is combined with a
contrast enhanced CT pyelogram to facilitate accurate representation of the calyceal anatomy and planning
of percutaneous tracks [12]. Lowe et al. conducted a study in which they demonstrated the importance of
abdominal and pelvic CT in revealing multiple ureteric calculus in the patients with acute flank pain [13].

Some additional imaging procedures are also important such as Radionuclide imaging, Magnetic
resonance urography (MRU) and retrograde ureterorenography. Radionuclide imaging using 99mTc-MAG3
can be of use in determining the secondary effects of calculi, namely obstruction and subsequent relative

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loss of function between the two kidneys [14]. It is especially useful in the determination of ongoing
obstruction in those patients with long-standing ureteric/pelvicalyceal dilation. Magnetic resonance
urography (MRU) can be utilized for children or pregnant patients where radiation is contraindicated. It
allows for depiction of ureteric/pelvicalyceal dilation as a result of obstruction, but accurate identification
of a calculus may be challenging as many artefacts mimicking stones may be encountered [15]. Retrograde
ureterorenography can be performed to demonstrate and assist in the removal of stones at cytoscopy and
ureteroscopy through endoscopic cannulation of the ureter and subsequent retrograde injection of
contrast material [16]. However, retrograde ureterorenography may be utilized if other investigations have
proven inconclusive.

Each modality has its differing strengths and weaknesses, and the choice of imaging technique
should always relate back to the strength of clinical suspicion. In those non-emergent patients with vague
symptoms, investigation with plain film KUB and ultrasound may be sufficient. However, it is now well
established that CT-KUB is the gold standard investigation for the diagnosis of urinary tract stones and its
use in the acute setting is the optimal means of investigating urinary calculi. (6) In this study, we have
evaluated the efficiency and reliability of CT scan for the diagnosis of urolithiasis in the patients with flank
pain.

MATERIALS AND METHODS

A prospective study was conducted on 50 patients (33 male & 17 female; Age: 2-60 years) with
clinical impression of urolithiasis. This study has been approved by the institutional review committee of
S.V.S.U. Subharti Medical College, Meerut, India. All patients with radiologically diagnosed Urolithiasis were
included in this study. However, pregnant patient and the patients having contrast allergy were excluded
in this study. The clinical history of each patient was recorded and underwent routine biochemical
investigations as per Performa. Flank pain was the most common clinical Symptom. In this study, CT
imaging was performed with 128 slice Philips ingenuity CT scanner.

The procedure was briefly explained to the patient including the risks of contrast examination.
Routine blood investigation like serum creatinine was mandatorily performed on patient before
performing contrast enhanced CT. Patients were advised to take nothing but clear liquids at least 4 hours
before the exam. Informed consent was taken from all the patients before CT examination. All the metallic
objects were removed from the body before CT examination. Proper breathing instruction was given to the
patient. Image acquisition of patients was taken during full bladder. Non-ionic contrast media was used for
enhanced CT whenever prescribed. CT acquisition and the diagnosis of urolithiasis was done as by the
qualified technologist and radiologists respectively as per departmental protocols. CT acquisition
parameters have been presented in the table 1. Statistical analysis were done using SPSS 19.

RESULTS

Among the 50 patients who had undergone for CT examinations to rule out nephrolithiasis, 66%
were male and 34% were female as shown in Figure 1. In this study, patients from 2 years to 60 years were
included for CT imaging. Study population has been presented on the basis of age distribution as shown in
figure 2. During the CT image interpretation of 50 patients, 28 patients (56%) had stone in kidneys
(nephrolithiasis), 2 patients (4%) had PUJ calculus, 14 patients (28%) had ureterolithiasis and 6 patients
(12%) had VUJ calculus as shown in figure 3. In this study, we did not find any patient with cystolithiasis.
We have also presented the results on the basis of sidewise distribution of renal stones. Among 50 patients,
we found that the maximum number of patients (40%) had stone in right side as shown in figure 4. As per
figure 5, maximum number of the patients (70%) have unilateral stone. Figure 6 shows the CT images of
the patients diagnosed with left and right renal calculi. Figure 7 shows patient having bilateral
nephrolithiasis. Figure 8 shows the CT image of patient having left proximal ureteric calculus.

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Table 1

CT Scan Parameters
Patient position Supine
Patient orientation Feet first
Centre Xiphisternum
Anatomical landmarks Mid axillary line
Field of view Diaphragm to pubic symphysis
Mode of sequence Inspiratory scan
Scan type Helical
Scan orientation Cranio caudal
Gantry tilt 0 degree
Slice thickness 5mm
Pith 1
Reconstruction 1.5mm
Kvp 120
mAs 250

Percentage

34%

66%

Male Female

Figure 1: Sex distribution in study population

100
90
80
70
60
50
40
30
20
10
0
≤ 20 21 - 30 31 - 40 41 - 50 51- 60 >60 Total
years years years years years years

Cases Percent

Figure 2: Age distribution in study population

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160
140
120
CASES PERCENTAGE
100
80
60
40
20
0

Figure 3: Distribution of patients on the basis of site.

160
140
120
100 100
80
60
40 40
30 30 50
20 15 20 15
0
LEFT RIGHT Bilateral Total

Cases Percent

Figure 4: Sidewise distribution

Unilateral & Bilateral

150

100

50

0
Unilateral Bilateral Total

cases percentage

Figure 5: Distribution of unilateral and bilateral

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A B

Figure 6: CT images shows left (A) and right (B) nephrolithiasis.

Figure 7: CT images shows bilateral nephrolithiasis.

A B

Figure 8: CT images shows left (A) and right (B) proximal ureteric calculus.

DISCUSSION

A prospective study was done to evaluate the efficiency and reliability of Computed Tomography
in the evaluation of renal calculi and to assess the site of urolithiasis. In the present study it was observed
that 21 to 60 years (80%) were the most common age group in the population followed by above 60 years
(14%) and less than 20years (6%). Among the 50 patients, the mean of the affected gender was found to
be 33 male patients (66%) and 17 female patients (34%) which shows that the males were affected more
than female. The most common side affected was right side (40%) followed by left side (30%) and bilateral
(30%). Most of the patients had unilateral (70%) followed by bilateral (30%). In the present study, it was
observed that Nephrolithiasis (56%) and ureterolithiasis (28%) were the most common in patients with
urolithiasis. Thoeny et al. performed unenhanced spiral CT to investigate patients with acute flank pain to
diagnose suspected urinary tract calculi where they concluded that CT scan can frequently detect or

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exclude other causes of acute flank pain, thus guiding subsequent imaging and the therapeutic management
[17].

In this study non contrast CT scan is used because it plays a vital role in evaluating Urolithiasis.
Use of CT imaging has increased dramatically over the last two decades in many countries. Approximately
72 million scans were performed in the United States in 2007 and more than 80 million a year in 2015. A
non-contrast helical CT scan with 5 millimeters sections is the diagnostic modality of choice in the
radiographic evaluation of suspected nephrolithiasis. Lund et al. assessed the inter-observer variability of
unenhanced helical computed tomography (UHCT) in patients with acute renal colic admitted into a low-
volume hospital and found that the UHCT method to be safe and reliable with a good inter-observer
agreement and Kappa value [18]. All stones are detectable on CT scans except very rare stones composed
of certain drug residues in the urine, such as from indinavir. Calcium-containing stones are relatively radio
dense, and they can often be detected by a traditional radiograph of the abdomen that includes the kidneys,
ureters, and bladder (KUB radiograph). Approximately 60% of all renal stones are radiopaque. In general,
calcium phosphate stones have the greatest density, followed by calcium oxalate and magnesium
ammonium phosphate stones. Cystine calculi are only faintly radio dense, while uric acid stones are usually
entirely radiolucent. Huang et al. determine the ability of low- and conventional-dose CT in identification
of uric acid stones, which are of lower density than calcium oxalate stones. In their study both low- and
conventional-dose CTs demonstrate excellent sensitivity and specificity for the detection of ureteral uric
acid stones. Andrabi et al. discussed the current and emerging role of CT in the management of patients
with urinary stone disease and their impact on planning treatment strategies and patient follow-up [10].

Further CT advances include the use of dual source imaging, a relatively new technique that utilizes
two X-ray tubes and two detector units, which can be used to extract virtual ‘non-contrast’ images from
contrast enhanced data and allows for determination of the chemical content of stones. In particular, this
method is useful for distinguishing uric acid stones from calcium stones, as the former can be treated
noninvasively with urine alkalinisation. The disadvantage of CT imaging is that it uses ionizing radiation.
The effective dose from a MDCT KUB is dependent upon many factors such as patient habitus, the type of
CT scanner and scanning protocol utilized. However it is estimated that approximately 2–9mSv dose is
received from an abdominal CT compared to 0.5mSv for an abdominal radiograph.

CONCLUSION

In this study, our result confirms the significant role of non-contrast computed tomography scan
in evaluating Urolithiasis. From the results, it is now well established that computed tomography – KUB is
the gold standard investigation for the diagnosis of urinary tract stones.

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