Intravenous (IV) urography has been conventionally used for imaging of the upper urinary tract. However, recently, this imaging technique has largely been replaced by CTU [1]. Some of the common conditions that are referred for a CTU investigation include renal calculi formation, haematuria, flank and abdominal pain, suspected renal or urothelial neoplasm, a variety of inflammatory conditions, and congenital anomalies of the kidneys and ureters [2].
The new generation CT scanners have better speed and spatial resolution. They have advanced multiplanar and volume-rendered image reconstruction capacity. This helps imaging of kidneys, ureters and urinary bladder at one go. Also, CTU is often used as a screening tool for imaging the urothelium in patients at high risk for developing bladder cancer [3].
CTU combines the advantages of excretory urography with cross-sectional imaging into a single investigation that is capable of accurately visualising the renal parenchyma, collecting system and ureters [4]. This technique is based on the acquisition of non-enhanced and enhanced CT scans of the abdomen and pelvis. It includes acquisition of thin section helical CT scans of the urinary tract during the excretory phase of enhancement. Multiplanar 2-Dimensional (2D) and 3-Dimensional (3D) reformation images are produced from axial source images during the excretory phase. CTU enables a single breath-hold inclusion of the whole urinary tract, faster imaging and the partial volume effect is reduced [5].
The primary aim of the study was to evaluate the role of MDCT urography in the diagnosis of renal tract abnormalities and to corelate clinical features with the imaging results.
Materials and Methods
This was a descriptive study that was conducted between November 2017 and November 2019, involving Fifty patients (29 male and 21 female, from outpatients, inpatients, and referral Departments of Rajarajeswari Medical College and Hospital and Institute of Nephro-urology, Bengaluru, India. The study was approved by the Institutional Ethics Committee (RRJMC-RD-11/17-321) and informed consent was taken from all the study participants.
Inclusion criteria: Patients with suspected
Urinary tract calculi, infections
Renal parenchymal masses
Renal papillary or medullary abnormalities, collecting system abnormalities
Congenital anomalies of kidneys and ureters
Renal cystic diseases
Diseases of the urinary bladder and
Postoperative patients between 18 and 80 years of age
Exclusion Criteria:
Patients below 18 and above 80 years of age
Pregnant women
Renal failure patients
Cardiac failure patients
those with allergy to contrast media
Procedures
Triphasic examinations, including non-contrast, contrast enhanced and delayed imaging was carried out. Non-contrast imaging was carried out from the top of the kidneys through the bladder. The aim was to check for the presence of calculi, fat-containing lesions, parenchymal calcifications and to provide baseline attenuation for assessment of lesion enhancement. Contrast media was administered intravenously. After a delay of 90 to 100 seconds, scanning of the abdomen and pelvis was performed during the nephrographic phase. The final acquisition was obtained during the excretory phase after a delay of 12 to 15 minutes. During this phase, opacification and distention of the collecting systems, ureters and bladder was observed.
Scanning was carried out using a multi-detector row CT scanner (Siemens 128 slice). CT scans were obtained from the kidneys to the bladder using the following parameters: (i) collimator-5 mm; (ii) pitch- 1.5/2 Hz; and (iii) current- 120 mA. The thickness of the reconstructed images was 1 mm. A 3D reconstruction of the non-enhanced, nephrogenic phase and excretory phase were performed as and when required. The follow-up diagnosis was established on the basis of histopathologic findings or the findings of urologic procedures, such as cystoscopy, ureteroscopy or retrograde pyelography.
Statistical Analysis
In the present study, descriptive and inferential statistical analysis were carried out. Continuous measurements were presented as mean±SD (min-max) and categorical measurements were presented as number and percentage (%). A 5% level of significance was used in the present study. Chi-square and Fisher’s-Exact Test were used to assess the significance of study parameters on categorical scale between two or more groups.
The Statistical Package for the Social Sciences (SPSS) (Version 18.0) and R environment (Version 3.2.2) were used for data analysis and MS Word and MS Excel were used for generating the graphs and tables. p-value <0.05 was regarded as moderately significant, while a p-value <0.01 was regarded as highly significant.
Results
Age Distribution
The study included patients aged between 18 and 80 years. Maximum number of patients were seen in the age group 31-40 years, consisting of 15 (30%) patients. This was followed by the age group 20-30 years 9 (18%) patients, making up 18% of all patients. The least number of patients were in the age group >70 years, consisting of only 2 (4%) patients. The average age of the patients was 41.84±16 years (mean±SD).
Clinical Symptoms
The presentation of clinical symptoms is mentioned in [Table/Fig-1]. Some of the patients presented with more than one symptoms. Forty patients (80%) complained of abdominal pain. Seventeen patients (34%) presented with haematuria, 12 patients (24%) had fever, while 4 patients (8%) reported loss of weight [Table/Fig-1].
Clinical symptoms of patients.
| Clinical symptoms | No. of patients | Percent (%) |
|---|
| Abdominal pain | 40 | 80 |
| Fever | 12 | 24 |
| Weight loss | 4 | 8 |
| Haematuria | 17 | 34 |
Pathology
The pathological conditions that were studied included: (1) urolithiasis; (2) congenital anomalies; (3) infections; (4) renal masses; (5) cysts; and (6) others.
Urolithiasis
Urolithiasis was found in 18 out of 50 patients (36%) and was the most common pathology diagnosed. Calculi were identified in 8 patients (16%) on the left side (kidney/pelvi ureteric junction/ureter/vesico-ureteric Junction) and in 6 patients (12%) on the right side (kidney/pelvi ureteric junction/ureter/vesico-ureteric junction). Four patients (8%) were found to have calculi in the bladder.
Out of the 18 patients diagnosed with urolithiasis, 11 patients (22%) had renal calculi. Four patients (8%) had staghorn calculi (since the calculi resemble the horn of a stag or male deer), 3 patients (6%) had calculi in upper and lower calyx and 1 patient (2%) had calculi in the middle calyx.
Three patients (6%) had calculi in the pelvi ureteric junction, 3 patients (6%) had calculi in the ureter, 1 patient (2%) in the vesico ureteric junction and 2 patients (4%) in the bladder [Table/Fig-2].
Distribution of calculi in patients.
| Presence/Location/Type of calculi | No. of patients | Percent (%) |
|---|
| No | 32 | 64 |
| Yes | 18 | 36 |
| Left | 8 | 16 |
| Right | 6 | 12 |
| Bladder | 4 | 8 |
| Kidney |
| No | 39 | 78 |
| Yes | 11 | 22 |
| Staghorn | 4 | 8 |
| Lower calyx | 3 | 6 |
| Upper calyx | 3 | 6 |
| Middle calyx | 1 | 2 |
| Pelvi-ureteric junction |
| No | 47 | 94 |
| Yes | 3 | 6 |
| Ureter |
| No | 47 | 94 |
| Yes | 3 | 6 |
| Distal | 2 | 4 |
| Proximal | 1 | 2 |
| Vesico-ureteric junction |
| No | 49 | 98 |
| Yes | 1 | 2 |
| Bladder |
| No | 48 | 96 |
| Yes | 2 | 4 |
Congenital Anomalies
Out of 50 patients, 38 (76%) did not have any congenital anomalies, while 12 patients (24%) had these anomalies. The most common congenital anomaly diagnosed was pelvi-ureteric junction obstruction, which was seen in 6 cases. Other congenital anomalies diagnosed were mega ureter, crossed fused ectopic kidney, and duplex collecting system.
Infections
Out of 50 patients, 43 (86%) did not have any infections. Seven patients (14%) had infection in the renal tract. The most common infection was acute pyelonephritis, which was diagnosed in 4 patients (57%). The remaining infections caused cystitis, which was diagnosed in 3 patients (43%).
Renal Masses
Renal masses were seen in 7 cases (14%), while 43 (86%) did not exhibit any masses. Out of the 7 cases, 4 patients (8%) had masses in their left kidney, 1 patient (2%) in the right kidney and 2 patients (4%) in their urinary bladder. Three of the 5 masses in the kidneys were histopathologically proven to be renal cell carcinoma and the bladder masses turned out to be transitional cell carcinoma. One patient exhibited angiomyolipoma.
Cysts
Cysts are membranous sacs or cavities within the body that have an abnormal character and contain fluids. Cysts were seen in 7 cases (14%), while 43 (86%) did not exhibit any cysts. Three patients (6%) showed cysts in their left kidney, 3 patients (6%) showed cysts in both kidneys (bilateral), and 1 patient (2%) showed cysts in the right kidney.
Others
Some of the other conditions in this category included collecting system abnormalities, papillary abnormalities, and urinary bladder pathology. Bladder pathologies included calculi formation, urothelial tumours, bladder diverticula, and bladder malignancies of various types. Bladder pathology was found in 6 patients (12%), collecting system abnormality (stricture) was found in 1 patient (2%) and 1 post-nephrectomy patient (2%) underwent CT. There were no cases of papillary abnormalities.
Secondary Signs and Incidental Findings
The secondary signs include hydronephrosis, hydroureteronephrosis and delayed renal excretion. Hydronephrosis/hydroureteronephrosis were found in 15 patients (30%) and delayed renal excretion was found in 2 patients (4%). Incidental findings which were not related with the renal tract, such as cholelithiasis, hepatosplenomegaly, uterine fibroids and ovarian cysts were found in 6 patients (12%) [Table/Fig-3].
Secondary signs and incidental findings.
| Condition | No. of patients | Percent (%) |
|---|
| Hydronephrosis/Hydroureteronephrosis | 15 | 30 |
| Delayed renal excretion | 2 | 4 |
| Incidental findings | 6 | 12 |
Diagnosis
Of the 50 cases that were clinically suspected as having renal tract abnormalities, it was possible to correctly diagnose 48 patients (96%), using MDCT urography. The other 2 cases which were clinically suspected to have renal tract abnormality turned out to have no pathology on MDCT urography.
Among the 48 cases with renal tract abnormality, the most commonly diagnosed pathology was urolithiasis which was observed in 18 cases (36%). This was followed by congenital anomalies, which was observed in 12 cases (24%). Renal masses, infections and cysts accounted for 7 cases (14%) each. Other conditions, such as bladder pathology, collecting system abnormality and postoperative cases were observed in 16% of patients [Table/Fig-4].
Diagnosis of various conditions in patients.
| Diagnosis | No. of patients | Percent (%) |
|---|
| Normal study | 2 | 4 |
| Positive cases | 48 | 96 |
| Urolithiasis (calculi) | 18 | 36 |
| Congenital anomalies | 12 | 24 |
| Infection | 7 | 14 |
| Mass | 7 | 14 |
| Cysts | 7 | 14 |
| Bladder pathology | 6 | 12 |
| Collecting system abnormality | 1 | 2 |
| Papillary abnormality | - | - |
| Postoperative | 1 | 2 |
Correlation of Clinical Features in Patients with Urolithiasis
Among the patients referred for MDCT urography, pain was the only clinical symptom that had a significant correlation with the presence of urolithiasis [Table/Fig-5].
Clinical features associated with urolithiasis.
| Clinical features | Presence of urolithiasis | Total (n=50) | p-value |
|---|
| No (n=32) | Yes (n=18) |
|---|
| Pain | 22 (68.7%) | 18 (100%) | 40 (80%) | 0.009** |
| Fever | 8 (25%) | 4 (22.2%) | 12 (24%) | 1.000 |
| Weight loss | 4 (12.5%) | 0 (0%) | 4 (8%) | 0.283 |
| Haematuria | 9 (28.1 %) | 8 (44.4%) | 17 (34%) | 0.242 |
Chi-square/Fisher’s-exact test; **Highly significant
Correlation of Clinical Features in Patients Exhibiting Congenital Anomalies
Among the patients referred for MDCT urography, haematuria was the only clinical feature that had a significant correlation with the presence of congenital anomalies [Table/Fig-6].
Clinical features associated with congenital anomalies.
| Clinical features | Congenital anomaly | Total (n=50) | p-value |
|---|
| No (n=38) | Yes (n=12) |
|---|
| Pain | 31 (81.6%) | 9 (75%) | 40 (80%) | 0.686 |
| Fever | 11 (28.9%) | 1 (8.3%) | 12 (24%) | 0.248 |
| Weight loss | 4 (10.5%) | - | 4 (8%) | 0.560 |
| Haematuria | 16 (42.1%) | 1 (8.3%) | 17 (34%) | 0.039* |
Chi-square/Fisher’s-exact test; *Moderately significant
Correlation of Clinical Features in Patients with Renal Masses
Among the patients referred for MDCT urography, weight loss and haematuria were the only two clinical features that had significant correlation with the presence of renal masses [Table/Fig-7].
Clinical features associated with renal masses.
| Clinical features | Renal masses | Total (n=50) | p-value |
|---|
| No (n=43) | Yes (n=7) |
|---|
| Pain | 35 (81.4%) | 5 (71.4%) | 40 (80%) | 0.616 |
| Fever | 11 (25.6%) | 1 (14.3%) | 12 (24%) | 1.000 |
| Weight loss | - | 4 (57.1%) | 4 (8%) | <0.001** |
| Haematuria | 12 (27.9%) | 5 (71.4%) | 17 (34%) | 0.037* |
Chi-square/Fisher’s-exact test; *Moderately significant; **Highly significant
Discussion
The present study included 50 patients who were strongly suspected to have urinary tract abnormalities. Triphasic MDCT urography was carried out, which included non-contrast, contrast enhanced and delayed images. Non-contrast images extending from the top of the kidneys through the bladder were generated. Intravenous contrast media was administered and following a delay of 90-100 seconds, the abdomen and pelvis were scanned. The final acquisition was during the excretory phase after a delay of 12-15 minutes.
Urinary tract abnormalities were classified into urolithiasis, congenital anomalies, renal mass formation, infections, cyst formation, bladder pathology, collecting system abnormalities, papillary abnormalities, and postoperative patients. Secondary signs were noted, which included hydronephrosis/hydroureteronephrosis and delayed renal excretion. Incidental findings, which were not related to the renal tract, such as cholelithiasis, hepatosplenomegaly, uterine fibroids, and ovarian cysts were also recorded.
Clinical features were noted under four categories, which included abdominal pain, fever, weight loss and haematuria. Moreover, clinical features were correlated with the presence of urolithiasis, congenital anomalies and renal mass formation as they were the most commonly observed urinary tract abnormalities.
Urolithiasis is the formation of calcified stones or calculi within the urinary system. Calcification within the lumen of the urinary tract is known as nephrolithiasis, whereas intraparenchymal calcification is termed as nephrocalcinosis [6].
The congenital anomalies of the kidneys included horseshoe kidney, renal ectopia with or without crossed-fusion, hypertrophied column of Bertin, and renal agenesis. Anomalous kidneys may also have complications, such as duplicated ureters, stone disease, vesico-ureteric reflux, traumatic injury, and pelvi-ureteric junction obstruction. These can all be detected by MDCT urography [7,8].
With regard to infections, pyelonephritis was the most common infection. Pyelonephritis is the inflammation of the kidneys as a result of bacterial infection. It exhibits a number of symptoms, including bacteriuria, pyrexia and flank pain. Pyelonephritis may occur due to ascending infection caused by Escherichia coli in 85% of cases or due to haematogenous seeding caused by Staphylococcus aureus in 15% of cases [9].
Renal masses can be benign and malignant. These may include renal cell carcinoma and angiomyolipoma, especially during the nephrographic phase. Other less common masses include renal lymphoma (primary or secondary), transitional cell carcinoma, multilocular cystic nephroma, oncocytoma, and metastatic disease [10]. The most common abnormality to be diagnosed was urolithiasis. The location and morphology of the calculi were noted. Pre-contrast phase of MDCT urography could correctly diagnose calculi in all cases of urolithiasis.
Retrospective comparison of the results of MDCT urography with other clinical results (pyeloureteroscopy, surgery or spontaneous passage of the calculi) and imaging examinations (retrograde pyelography or sonography) were performed.
The mean age of the patients in the present study was 41.84±16 years. This was correlated with studies carried out by Lin WC et al., and Caoili EM et al., [1,5]. There was no significant correlation between age and renal tract abnormalities in the present study.
Urolithiasis was the most common renal tract abnormality found in the present study, which was observed in 18 patients (36%). This was similar to the findings of the study conducted by Lin WC et al., [1], where 38% of the patients were diagnosed with urolithiasis. However, the study conducted by Caoili EM et al., found that only 8% of the patients had urolithiasis [5]. Kumar R et al., studied 50 patients with haematuria, out of which 20% had renal calculi [11]. In a study by Shamachar VK et al., renal calculi were the most common abnormality among the 100 patients studied for the evaluation of ureter abnormalities [12].
In the present study, all the 18 patients with urolithiasis were diagnosed in the pre-contrast phase of MDCT urography. Most of the patients diagnosed with urolithiasis were between 30-50 years of age. In the study by Kumar R et al., renal calculi were more common among younger age group of patients [11]. Similar results were shown in the study by Shamachar VK et al., [12]. Hundred patients were studied and renal calculi were found more commonly in younger age group. Abdominal pain was the only statistically significant clinical feature associated with urolithiasis in the present study. In the other studies, there was no correlation between clinical symptoms and diagnosis.
In the present study, congenital anomalies were diagnosed in 12 patients (24%), which were higher compared to the studies conducted by Lin WC et al., and Caoili EM et al., [1,5]. The most common age group in which congenital anomalies occurred in the present study was 31-40 years. The most common congenital anomaly detected in the present study was pelvi-ureteric junction obstruction, which was observed in 6 out of 12 cases. There was no significant clinical feature that correlated with the congenital anomalies in the present study. In the study by Shamachar VK et al., the most common ureter anomalies were pelvi-ureteric junction obstruction and vesico-ureteric reflux [12].
In the present study, 14% of patients had renal masses, which is almost similar to the other studies conducted by Lin WC et al., and Caoili EM et al., [1,5]. In the study by Kumar R et al., 16% of patients with haematuria had urothelial carcinoma and 6% of patients with haematuria had renal cell carcinoma [11]. Haematuria and loss of weight were the only two statistically significant clinical features that were associated with malignancy in the present study. Renal mass formation was confirmed by postoperative follow-up of the patients.
Limitation(s)
The sample size was small, compared to the spectrum of renal tract abnormalities that were present. Not all patients with suspected renal tract abnormalities could undergo MDCT urography due to financial constraints. As pregnant women were excluded from the study, the role of MDCT urography in these women could not be evaluated. Since, the study included patients between 18 and 80 years of age, abnormalities diagnosed before 18 years and after 80 years could not be assessed.
Conclusion(s)
Based on the study findings, it may be concluded that MDCT urography is a very powerful and useful diagnostic tool for the detection and evaluation of renal tract abnormalities.