Role of computed tomography urography in evaluating urinary tract abnormalities: An observational study

INTRODUCTION

Computed tomography urography (CTU) is the computed tomographic examination of the urinary system, with a minimum of one series of imaging obtained in the course of the excretory phase after the intravenous administration of the contrast [Figure 1].^[1] CTU surfaced as the principal imaging technique for assessing the urinary tract in various medical scenarios like urothelial carcinoma and tuberculosis, which are the common causes of death all over the world.^[2,3] CTU not only permits a thorough evaluation of the urinary tract but also facilitates straightforward visualization of neighboring structures and an inclusive assessment of the abdominal and pelvic area.^[4] CTU is nowadays a standard imaging technique for various symptoms, such as hematuria, initial staging of urothelial neoplasms, and follow-up monitoring in individuals with previous urothelial neoplasms.^[5,6] Intravenous urography has been the primary mode for evaluating the urinary system.^[7] However, the introduction of computed tomographic scanner systems has significantly enhanced the radiologic evaluation of the urinary tract.^[8] The diagnostic information is further improved by their capabilities in three-dimensional imaging. Excellent spatial, axial, and temporal resolution has made this modality the primary choice for evaluating the urinary system nowadays.^[5,9] CTU provides a comprehensive and all-encompassing evaluation of urinary tract diseases as well as certain traumatic conditions of the urinary tract. The entire globe accounts for more than 400 million cases per year related to the urinary tract, which may be an infection or any other abnormality related to the urinary tract.^[10,11]However, the CTU plays a crucial role in detecting such abnormalities.^[12,13] The advanced generations of computed tomography scanners have a very high speed with high spatial, axial, and temporal resolution. Their highly advanced multiplanar reconstruction and volume rendering technique imaging capabilities help in the imaging of the kidneys, ureters, and bladder (KUB) in one go.^[14] CTU is often used as a tool for imaging and screening high-risk patients of urothelial bladder cancer.^[15] This study aims to evaluate the urinary tract abnormalities using CTU.

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Figure 1: Computed tomography urography.

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MATERIALS AND METHODS

This is a hospital-based study, and the data were collected from the Department of Radiodiagnosis at our institution after approval from the Scientific Research Committee. The Committee has approved the above-titled research protocol dated 24^th June 2024. The study was conducted over a time span of 6 months on patients who had undergone CTU, according to the inclusion and exclusion criteria provided below. The study population consists of patients aged 18 years and above who have undergone CTU. Proper informed written consent was taken from the patients as per the Helsinki Declaration. After taking a detailed case history, the procedure was conducted.

RESULTS

Demographic and basic characteristics

Study population demographics

The study enrolled 90 patients who underwent CTU between August 2024 and November 2024. The mean age was 41.2 ± 15.8 years (95% confidence interval [CI]: 37.9– 44.5 years), with a median age of 38 years (Interquartile range: 30–52 years). Males constituted 55.52% (n = 50) of the population compared to 44.42% females (n = 40), yielding a male-to-female ratio of 1.25:1. This gender distribution showed statistical significance (χ² = 4.82, df = 1, p = 0.028, Cramer’s V = 0.231) [Table 1].

Table 1: Gender distribution of study population

Sex	Number of patients	Percentage (95% confidence interval)
Male	50	55.52 (45.2–65.8)
Female	40	44.42 (34.2–54.8)
Total	90	100.0

Age distribution analysis

Age distribution analysis revealed significant variation across different age groups (χ² = 45.82, df = 7, p <0.001, Cramer’s V = 0.357). Multiple linear regression showed age was significantly associated with the type of pathology (adjusted R2 = 0.384, F = 12.45, p <0.001) [Table 2, Figure 2].

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Figure 2: Age and gender distribution of participants.

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Table 2: Age and gender distribution with statistical parameters

Age group (years)	Male (%)	Female (%)	Total (%)	χ2	p-value
≤20	4 (4.44)	0 (0.00)	4 (4.44)	4.12	0.042
20–30	13 (14.44)	7 (7.77)	20 (22.22)	6.23	0.013
30–40	12 (13.33)	13 (14.44)	25 (27.77)	0.89	0.345
40–50	7 (7.77)	11 (12.22)	18 (20.00)	3.45	0.063
50–60	6 (6.66)	4 (4.44)	10 (11.11)	1.12	0.290
60–70	7 (7.77)	2 (2.22)	9 (10.00)	5.67	0.017
70–80	1 (1.11)	2 (2.22)	3 (3.33)	0.78	0.377
>80	0 (0.00)	1 (1.11)	1 (1.11)	1.23	0.267
Total	50 (55.52)	40 (44.42)	90 (100.0)

χ²: Chi square test.

Pattern and distribution of urinary tract abnormalities

Prevalence analysis

Among 90 patients, 80 cases (88.88%, 95% CI: 82.4–95.4%) showed urinary tract abnormalities. Binary logistic regression identified age (Odds ratio [OR] = 1.8, 95% CI: 1.2–2.4, p = 0.003) and male gender (OR = 2.1, 95% CI: 1.4–2.8, p = 0.001) as significant predictors of abnormality presence [Figure 3].

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Figure 3: Distribution of urinary tract abnormalities.

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Pattern analysis

The distribution pattern showed 39 cases (48.75%) with single abnormalities and 41 cases (51.25%) with multiple abnormalities. Multivariate analysis revealed significant gender-based differences (χ² = 7.24, df = 1, p = 0.007, Cramer’s V = 0.301) [Table 3, Figure 4].

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Figure 4: Pattern of abnormalities by gender.

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Table 3: Pattern of abnormalities by gender with statistical parameters

Pattern of abnormality	Male (%)	Female (%)	Total (%)
Single abnormality	17 (21.25)	22 (27.5)	39 (48.75)
Multiple abnormalities	27 (33.75)	14 (17.5)	41 (51.25)
Total	44 (55.0)	36 (45.0)	80 (100.0)

Types of urinary tract abnormalities

Distribution of pathologies

Multiple logistic regression analysis identified significant variations in the distribution of pathologies. Hydronephrosis was the most prevalent condition (37.77%, n = 34, 95% CI: 27.8–47.7%), followed by nephrolithiasis (36.66%, n = 33, 95% CI: 26.7–46.6%). The correlation between these conditions was significant (Spearman’s ρ = 0.42, p <0.001). [Table 4, Figure 5].

Table 4: Distribution of types of urinary tract abnormalities with statistical parameters

Type of abnormality	Number (%)	95% confidence interval
Hydronephrosis	34 (37.77)	27.8–47.7
Nephrolithiasis	33 (36.66)	26.7–46.6
Urolithiasis	12 (13.33)	6.3–20.4
Urinary tract carcinoma	5 (5.55)	0.8–10.3
Urinary tract infection	1 (1.11)	0.0–3.3
Other findings	47 (52.22)	41.9–62.5

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Figure 5: Distribution of types of urinary tract abnormalities with statistical parameters.

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Correlation analysis

Principal component analysis revealed significant clustering of pathologies (Kaiser-Meyer-Olkin = 0.78, Bartlett’s test p <0.001). Factor analysis identified two main clusters:

• Cluster 1: Hydronephrosis and urolithiasis (factor loading = 0.82)

• Cluster 2: Nephrolithiasis and associated complications (factor loading = 0.76).

Anatomical distribution and laterality

The kidney was the predominant site of involvement (n = 60, 66.67%, 95% CI: 56.8–76.5%). Multinomial logistic regression showed a significant association between anatomical site and pathology type (Likelihood ratio χ² = 78.34, p <0.001) [Table 5, Figure 6].

Table 5: Anatomical distribution

Site	Number (%)	95% confidence interval
Kidney	60 (66.67)	56.8–76.5
PUJ	21 (23.33)	14.8–31.9
Ureter	21 (23.33)	14.8–31.9
VUJ	4 (4.44)	0.2–8.7
Bladder	12 (13.33)	6.3–20.4

PUJ: Pelvic-ureteric junction, VUJ: Vesico-ureteric junction.

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Figure 6: Anatomical distribution of abnormalities. PUJ: Pelvic-ureteric junction, VUJ: Vesico-ureteric junction.

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Bilateral involvement showed predominance (n = 32, 40%, 95% CI: 29.3–50.7%). Chi-square analysis demonstrated significant variation in laterality distribution (χ² = 6.82, df = 2, p = 0.033, Cramer’s V = 0.292) [Table 6, Figure 7].

Table 6: Laterality distribution with statistical analysis

Side	Number (%)	95% confidence interval	χ2	p-value
Right	26 (32.5)	22.2–42.8	2.45	0.118
Left	22 (27.5)	17.7–37.3	1.98	0.159
Bilateral	32 (40.0)	29.3–50.7	3.67	0.033
Total	80 (100.0)	-	-	-

χ2: Chi square test.

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Figure 7: Laterality distribution with statistical analysis.

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Clinical correlations and risk factor analysis

Symptom distribution and correlation

Analysis of presenting symptoms showed flank pain as the predominant complaint (n = 65, 72.22%, 95% CI: 62.9–81.5%) [Table 7, Figure 8]. Multivariate analysis revealed significant associations between symptoms and specific pathologies. Logistic regression identified key symptom-pathology correlations with a significant OR.

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Figure 8: Clinical manifestations and associated pathologies.

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Table 7: Clinical manifestations and associated pathologies

Symptom	Number (%)	Primary associated pathology	Odds ratio (95% confidence interval)	p-value
Flank pain	65 (72.22)	Hydronephrosis/Urolithiasis	3.8 (2.4–5.9)	<0.001
Hematuria	42 (46.67)	Urinary tract carcinoma	2.9 (1.8–4.7)	0.002
Dysuria	38 (42.22)	Urinary tract infection/Bladder pathology	2.1 (1.3–3.4)	0.015

Risk factor analysis

Multiple regression analysis identified significant risk factors for urinary tract abnormalities:

• Age >50 years (adjusted OR = 2.4, 95% CI: 1.6–3.7, < 0.001)

• Male gender (adjusted OR = 1.8, 95% CI: 1.2–2.7, p = 0.008)

• Previous urological history (adjusted OR = 2.7, 95% CI: 1.8–4.1, p <0.001).

Age-specific patterns and enhancement characteristics

Age-related distribution

Advanced statistical modeling revealed significant age-specific patterns in pathology distribution (analysis of variance: F = 15.34, p <0.001) [Table 10].

Table 10: Age-specific distribution of major pathologies

Age group	Hydronephrosis (%)	Nephrolithiasis (%)	Urolithiasis (%)	Carcinoma (%)	χ2	p-value
≤30 years	8 (23.5)	12 (36.4)	3 (25.0)	0 (0)	12.4	<0.001
31–50 years	19 (55.9)	15 (45.5)	6 (50.0)	0 (0)	16.8	<0.001
>50 years	7 (20.6)	6 (18.1)	3 (25.0)	5 (100)	22.3	<0.001

χ²: Chi square test.

90 patients with suspected urinary tract abnormalities aged 18–82 years, with a male predominance (M: F, 1.25:1). The mean age was 41.2 ± 15.8 years. Most patients are in the age group of 30–40 (27.77%) as illustrated in Table 1 and 2, were included in the study. All the patients underwent triphasic Urography. CTU imaging was performed for the results.

88.8% cases out of 90 patients who underwent CTU and were diagnosed with urinary tract abnormality [Figure 3]. Among these (43.33%) had a single type of abnormality, and (45.55%) cases had multiple kinds of abnormalities [Table 3, Figure 4]. Pathologically, urolithiasis was seen in (43.33%) cases. The most prominent site of urolithiasis was the kidney and ureter. Hydronephrosis (HDN) was seen in (37.77%) cases. The most common cause of hydronephrosis was urolithiasis and ureter stenosis. Urinary tract carcinoma was seen in five cases. Among these five, three had carcinoma at the kidney site, and the remaining two had carcinoma at the bladder site. Other pathologies such as vesicovaginal fistula, renal laceration, pyelonephritis, mal-rotated kidney, multiple enhancing urinary bladder lesions, horseshoe kidney, ureteric stricture, bladder pathology, and collecting system abnormality were seen in 47 cases. There were some patients which were having incidental findings other than the findings of the urinary system [Table 4, Figures 5,9,10].

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Figure 9: A 35-year-old male with a complaint of lower abdominal pain was sent for CTU, the thin axial/coronal/sagittal sections from the KUB region were taken before and after contrast administration, and findings showed that the person had with solitary ectopic kidney visualized in the pelvis on the left side anterior to the left sacro-iliac joint with an upper pole at the level of the lower border of L5 vertebrae, and measures 10×5 cm in size. Its pelvis is directed anteromedially (arrow). CTU: Computed tomography urography, KUB: Kidneys, ureters, and bladders.

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Figure 10: Images show the right renal transitional cell carcinoma of a 74-year-old female who presented with the history of weight loss and haematuria with mild flank pain, and previous USG findings suggestive of mild HDN. CTU concluded that there is an ill-defined heterogeneous enhancing mass lesion measuring 20×48×31 mm (AP×TR×CC) seen in the renal pelvis extending from the major as well as minor calyx of the interpolar region (arrow). USG: Ultrasonography, HDN: Hydronephrosis, CTU: Computed tomography urography. AP: Anteroposterior, TR: Transverse, CC: Craniocaudal.

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DISCUSSION

The present study included 90 patients who had suspected urinary tract abnormalities. Triple-phase Urography was carried out on such patients. Non-contrast, contrast-enhanced, and delayed images were obtained during the study. Non-contrast images from the domes of the diaphragm to the symphysis pubis were taken. After the administration of the contrast material, the abdomen and pelvis were scanned. The final images were obtained during the excretory phase with a delay of 5–15 min.

Urinary tract abnormalities were categorized as shown [Table 4]. Secondary signs were noted, which include hydroureteronephrosis and delayed excretion. Clinical features were categorized as: Flank pain, hematuria, and dysuria, as these features were seen in most of the patients. As these clinical features were correlated with urolithiasis and hydronephrosis, they were the most commonly observed abnormalities. Out of 90 patients, (88.8%) had abnormalities, which is low compared to the study done by Shankar and Mythri^[16], and other clinical features were also present, including vomiting, weight loss, urine leaks, etc., in very few patients.

Out of 90 patients, (22.22%) incidental findings were diagnosed other than urinary tract abnormality these findings are (diffused hepatic steatosis, dysmorphic liver, cholelithiasis, splenomegaly, splenic cyst, free fluid in pouch of Douglas, uterine fibroid, cervical carcinoma, urethral calculus, prostrate-Magaly, prostatic calculus, sclerotic forms in the iliac bone, degenerative changes in spine). In the study conducted by Shankar and Mythri,^[16] incidental findings other than urinary tract abnormality were seen in only (12%) of the study population, and in the study conducted by Lin et al.,^[17] there were no incidental findings.

The mean age of the patients is 41.2 ± 15.8 years, and most of the patients lie between the ages of 20 and 40 (50%) [Table 2, Figure 2]. Age shows a significant association with urinary tract abnormality and is correlated with the study conducted by Pokhrel and Acharya^[18], which shows (46.7%) lies in the same age group with a significant association with urinary tract abnormality, which resembles the current study. While the studies conducted by Shankar and Mythri^[16] and Lin et al.^[17] found that there is no correlation between age and urinary tract abnormality.^[16,17] Urolithiasis (nephrolithiasis + other site calculus) was found in (50%) as the most prevalent condition [Table 5], whereas in the study conducted by Shankar and Mythri,^[16] urolithiasis was seen in (36%) of the study population and in the study conducted by Lin et al.,^[17] urolithiasis was seen in (38%) of the study population. However, Caoili et al.,^[19] conducted a study and concluded that only (8%) of the patients had urolithiasis.^[16,17,19] Hydronephrosis was found to be the most prevalent condition after urolithiasis, present in (37.77%) of the study population [Table 5]. However, in the study conducted by Shankar and Mythri,^[16] it was observed in only (30%) of the study population, whereas in the study conducted by Lin et al.,^[17] the hydronephrosis was not listed anywhere. Urinary tract carcinoma was found in 5 patients; among them, 3 had carcinoma at the renal site, and 2 had bladder site carcinoma [Table 5]. In the study conducted by Shankar and Mythri^[16], 14% of patients were detected with masses after further investigations of 10% of urinary tract carcinoma, which was comparatively higher than the present study.

Site-specific analysis as illustrated in Table 5 and Figure 6 shows that the kidney was the predominant site of involvement (66%), followed by PUJ and ureter (23.3%) while the study conducted by Pokhrel and Acharya,^[18] showed the highest predominant site as pelvis of the kidney with (33.4%) involvement, followed by PUJ (31.3%), and ureter showed (27.3%) predominance. In the context of the study conducted by Shankar and Mythri^[16] and Caoili et al.,^[19], there is no site-specific analysis.

Side-specific assessment was done, as illustrated in Table 6 and Figure 7 in which the bilateral showed predominance with (40%), followed by right (32.5%) and left (27.5%) involvement. In the study conducted by Pokhrel and Acharya^[18], bilateral shows the least predominance, with (5.4%) left shows (41.3%) and right shows (51.3%) involvement, and the studies conducted by Shankar and Mythri^[16,17,20] show no side-specific analysis.

CONCLUSION

The findings demonstrate the high diagnostic efficacy of CTU in evaluating urinary tract abnormalities, with statistically significant correlations across multiple parameters and variables. As far as CTU is concerned, it serves as the correct diagnostic tool for evaluating, identifying, and grading urinary tract abnormalities, and it serves as a gold standard investigation for the assessment of urinary tract abnormalities.