|Year : 2020 | Volume
| Issue : 3 | Page : 456-462
Role of duplex doppler ultrasound in evaluation of patients with diabetic nephropathy
Samar A Elshweehy1, Hosnia A Mohammed2, Sally M Osama2
1 Department of Diagnostic Radiology, Abbasia Psychiatric Hospital, Egypt
2 Department of Diagnostic Radiology, Faculty of Medicine for Girls, Al Azhar University, Cairo, Egypt
|Date of Submission||10-Jun-2020|
|Date of Decision||22-Jun-2020|
|Date of Acceptance||23-Jun-2020|
|Date of Web Publication||2-Oct-2020|
Samar A Elshweehy
Department of Diagnostic Radiology, Abbasia Psychiatric Hospital, Cairo, Nasr City
Source of Support: None, Conflict of Interest: None
Background Color Doppler evaluation of the renal parenchyma may suggest functional or structural changes within the kidneys and could provide useful diagnostic and prognostic information in diabetic nephropathy.
Aim The aim was to assess the usefulness of duplex sonography with Doppler waveform analysis in the evaluation and assessment of renal vascular resistance in diabetic patients.
Patients and methods This case–control prospective study included a total of 30 patients: 20 diabetic patients and 10 healthy controls. Renal parameters such as renal length, renal parenchymal thickness, parenchymal echogenicity, intrarenal resistive index (RI), and biochemical parameters such as fasting blood sugar, serum creatinine, and urine protein were recorded in all study participants. For the purpose of comparison, the diabetic patients were further subdivided into preclinical nephropathy, incipient nephropathy, overt nephropathy, and renal failure subgroups based on the stage of diabetic renal disease.
Results A progressive increase in renal RI values was noted with progression of diabetic nephropathy. RI values showed a positive correlation with albuminuria and serum creatinine, and this correlation was found to be statistically significant.
Conclusion Intrarenal RI measured by color Doppler ultrasonography has an important value in identifying diabetic patients who are developing nephropathy and can be used as an additional diagnostic tool in diagnosing diabetic nephropathy as well as to monitor progression of nephropathy.
Keywords: diabetic nephropathy, renal Doppler, resistive index
|How to cite this article:|
Elshweehy SA, Mohammed HA, Osama SM. Role of duplex doppler ultrasound in evaluation of patients with diabetic nephropathy. Sci J Al-Azhar Med Fac Girls 2020;4:456-62
|How to cite this URL:|
Elshweehy SA, Mohammed HA, Osama SM. Role of duplex doppler ultrasound in evaluation of patients with diabetic nephropathy. Sci J Al-Azhar Med Fac Girls [serial online] 2020 [cited 2020 Oct 26];4:456-62. Available from: http://www.sjamf.eg.net/text.asp?2020/4/3/456/296956
| Introduction|| |
Diabetic nephropathy is a major cause of end-stage renal disease throughout the world in both developed and developing countries . It is estimated that the death owing to renal disease is 17 times more common in diabetics than in nondiabetics. Diabetic nephropathy is a clinical syndrome characterized by the persistent albuminuria that is confirmed on at least two occasions 3–6 months apart .
Diabetes mellitus affects the whole vascular system, leading to both microvascular and macrovascular complications. In kidney, renal pathological changes leading to diabetic nephropathy are mainly secondary to atherosclerosis of the intrarenal and extrarenal arteries together with microangiopathy of the glomerular capillaries, afferent arterioles, and efferent arterioles. Diabetic nephropathy is a well-known microvascular complication of diabetes .
Renal resistive index (RI) is defined as a ratio of the difference between maximum and minimum (end-diastolic) flow velocity to maximum flow velocity derived from the Doppler measurements of main renal and intrarenal arteries. Duplex sonography provides an easily applicable, noninvasive, and well-established method for investigating renal functional or structural changes in diabetic nephropathy .
| Patients and methods|| |
This case–control prospective study included a total of 30 patients: 20 diabetic patients and 10 healthy controls. Renal parameters such as renal length, renal parenchymal thickness, parenchymal echogenicity, intrarenal RI, and biochemical parameters such as fasting blood sugar, serum creatinine, and urine protein were recorded in all participants. For the purpose of comparison, the diabetic patients were further subdivided into preclinical, incipient nephropathy, overt nephropathy, and renal failure subgroups based on stage of diabetic renal disease. All participants underwent conventional gray-scale renal ultrasound and Doppler evaluation of renal RI, from December 2018 to January 2020 after obtaining written informed patient consent. This study was approved by the Ethics Committee of our institute. The machine used in this study was Philips iU22 xMatrix DS Ultrasound (Philips Medical System Corporation, Eindhoven, the Netherlands).
Patients known to have long standing diabetes as a diabetic group and normal age-matched and sex-matched healthy participants with no medical disorders as a control group were included in the study.
Pregnant, children, nondiabetic patients, and cardiac patients are excluded from the study.
This is a prospective case–control study.
The clinical and histopathological results were collected then analyzed using SPSS version 23.0 software (SPSS Inc., USA). Pearson correlation coefficients and linear regression analysis were used to assess correlation between Duplex ultrasound and biochemical parameters in our study.
| Results|| |
This study included a total of 30 patients: 10 healthy controls (group 1) and 20 diabetic patients (group 2). Overall, nine (45%) of the diabetic cases were males and 11 (55%) were females, whereas four (40%) of the controls were males and six (60%) were females. There was no statistically significant difference in the male to female ratio between the two groups (P=0.8). Patients in group 2 were further divided into four subgroups based on the presence of nephropathy or not ([Figure 1]).
Gray-scale ultrasound analysis
The mean renal length was higher on the left side than on the right side in both the diabetic (113 mm vs 110 mmm, respectively) and control group (114 mm vs 111 mmm, respectively). The right and left renal length showed a progressive decrease with increased duration of diabetic renal disease (P=0.063). A progressive decrease also was noted in the mean renal parenchymal thickness of both kidneys with progression of diabetic renal disease (P=0.067). Majority of participants (90%) of the control group had normal parenchymal echogenicity, whereas 12 (60%) of the diabetic patients had normal parenchymal echogenicity with the remaining eight (40%) patients having varying degrees of renal parenchymal echogenicity ([Table 1] and [Figure 2]). Grades 2 and 3 renal parenchymal echogenicities were seen only among the diabetics with an overt nephropathy and renal failure.
|Table 1 Distribution of echogenicity grading of renal parenchyma among the various subgroups|
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|Figure 2 Distribution of echogenic grading of renal parenchyma among various subgroups.|
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Renal Doppler analysis
All of the patients in the preclinical nephropathy group (100%) had a normal RI value, whereas majority of the patients in the incipient nephropathy group (66.6%), in the overt nephropathy group (87.5%), and in the renal failure group (75%) had a raised resistivity index value, indicating a raised renal vascular resistance in these subgroups of patients ([Table 2]).
|Table 2 Relative percentages of normal and high resistivity values in various subgroups|
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The increased mean RI values (>0.7) obtained in the incipient nephropathy subgroup suggests that Doppler ultrasound can detect diabetic renal disease in this early stage.
The mean±SD resistivity index values in the control group, preclinical group, incipient nephropathy group, overt nephropathy, and renal failure groups were 0.61±0.05 SD, 0.65±0.04, 0.73±0.11, 0.78±0.07, and 0.82±0.06, respectively ([Figure 3]). A progressive increase in intrarenal RI value was noted with progression of diabetic renal disease, which was found to be statistically significant (P<0.001).
The mean values of renal resistive indices were compared among the diabetic patients based on the duration of diabetes. There was a statistically significant increase in mean RI ([Figure 4] and [Figure 5]) as the duration of diabetes increase (P<0.001).
|Figure 4 A 45-year-old male patient with a history of diabetes mellitus for 6 years. Gray-scale longitudinal ultrasonographic images of right kidney (a) and left kidney (b). Both kidneys demonstrate normal size (right kidney; 12×5.4 cm and left kidney; 10.6×5.9 cm), normal parenchymal thickness, normal parenchymal echogenicity, and no back pressure changes. Spectral waveform and resistive index recorded from upper polar segmental artery of right kidney (c) and upper polar segmental artery of left kidney (d), showing raised resistive index values of 0.77 and 0.78, respectively.|
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|Figure 5 A 58-year-old male patient, under hemodialysis with a history of diabetes mellitus for 23 years. Gray-scale longitudinal ultrasonographic images of right kidney (a) and left kidney (b). Both kidneys demonstrate relative small size and reduced parenchymal thickness and increased echogenicity with poor cortico-medullary differentiation (bilateral grade 3 echogenicity). Spectral waveform and resistive index recorded from right mid-zonal segmental artery (c) and left lower polar segmental artery (d), showing raised resistive index values of 0.81 and 0.82, respectively.|
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Association between RI and biochemical parameters
Pearson’s correlation was used to evaluate the association between RI and gray-scale ultrasound findings and biochemical parameters [fasting blood sugar (FBS), serum creatinine, and proteinuria]. There was strong positive correlation between RI and serum creatinine and proteinuria ([Table 3]).
|Table 3 Correlation between ultrasound, Doppler, and biochemical parameters|
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A positive r value represents a positive correlation, whereas a negative value represents a negative correlation between the parameters.
| Discussion|| |
Renal Doppler studies can play an essential role in the early detection of patients with diabetic nephropathy in correlation with other laboratory findings, and early detection of diabetic nephropathy will prompt proper therapy and proper prognosis for those patients .
In our study, bilateral renal length and renal parenchymal thickness were normal in the preclinical stage and showed a progressive decrease as the stages of diabetic renal disease progressed, but this decrease was not found to be statistically significant. This was in agreement with the study conducted by Gopalakrishnan et al. . In a similar study done by Shaw et al. , the renal length did not show linear variation with progression in severity of diabetic nephropathy, but the biggest kidneys were found in the preclinical subgroup.
Renal parenchymal echogenicity, which is considered to be a reliable sign of renal impairment at gray-scale imaging, was found to be a good indicator of diabetic nephropathy as the disease progressed. In our study, 100% of patients in the preclinical had normal renal parenchymal echogenicity. In our study, 60% (12/20) of diabetic patients showed abnormal renal parenchymal echogenicity, whereas the remaining eight (40%) patients having varying degrees of renal parenchymal disease. In their study, Shaw et al.  found that only 23.3% (14/60) of diabetic patients showed abnormal renal parenchymal echogenicity.
In our study, the mean RI in the control group (0.61+0.05 SD) was significantly lower than the mean RI in all stages of the diabetic nephropathy (0.79+0.08 SD). Moreover, the mean RI was significantly different among the different stages of diabetes. Resistive indices were 0.65, 0.73, 0.78, and 0.82 in diabetes without nephropathy, diabetes with incipient nephropathy, diabetes with overt nephropathy, and stage of renal failure, respectively. This is similar to the study by Sistani et al.  in which they reported RI of 0.66, 0.69, 0.74, and 0.85 in diabetes without nephropathy, diabetes with incipient nephropathy, diabetes with overt nephropathy, and renal failure, respectively.
A total of 70% of diabetic patients had increased RI values (>0.7); all patients belonging to preclinical subgroup (100%) had normal RI value (<0.7), whereas most of the patients belonging to incipient nephropathy (66.6%), overt nephropathy (87.5%), and renal failure subgroups (75%) had increased renal RI. In a similar study done by Shaw et al. , 68.3% of the patients had increase RI values (>0.7), major percentage of patients belonging to preclinical subgroup (70.5%) had normal RI value (<0.7), whereas most of the patients belonging to incipient nephropathy (72.7%), overt nephropathy (80%), and renal failure subgroups (90.9%) had increased renal RI, indicating increased renal vascular resistance as the disease progressed, which is similar to our results. Sistani et al.  reported that RI greater than or equal to 0.7 has been defined to be capable of representing kidney function in diabetic patients with microalbuminuria or macroalbuminuria.
In this study, the overall RI in diabetic nephropathy was 0.79±0.08, which showed the highest level in stage of nephropathy with renal failure, with a mean of 0.82±0.06, and the lowest was seen in stage of diabetes without nephropathy, with a mean of 0.65±0.04. Similar to our results, Sistani et al.  found that the overall RI in diabetic nephropathy was 0.76±0.09, which showed the highest level in stage of nephropathy with renal failure with a mean of 0.83±0.09 and the lowest was seen in stage of diabetes without nephropathy with a mean of 0.63±0.03.
This study revealed progressive increase in mean RI values with increase in severity of diabetic nephropathy, which was found to be statistically significant (P<0.001). In preclinical stage, the mean RI value of 0.65±0.04 SD is in normal range (<0.70) and suggests inability of intrarenal RI to detect changes in asymptomatic patients without microalbuminuria. However, in presence of microalbuminuria, the mean RI values are higher than 0.7, and it is significantly higher than preclinical subgroup (P<0.001). Gopalakrishnan et al. carried out their study with similar subgroup, and they reported mean RI in four subgroups as follows: 0.641±0.06, 0.724±0.10, 0.756±0.05, and 0.820±0.09, respectively, which was also statistically significant, and the mean RI values were pathological for diabetic nephropathy subgroups .
In this study, the RI increased as the duration of DM increased. Similar to our results, Dawha et al.  found a significant positive correlation between duration of diabetes and renal RI.
In our study, there was a strong positive correlation between RI and serum creatinine (r=0.4745, P<0.001) and albuminuria (r=0.4234, P<0.001). Moreover, diabetic patients with high serum creatinine greater than 1.4 mg/dl were more likely to have abnormal RI greater than 0.7 than those with serum creatinine less than 1.4 mg/dl (P<0.001). The same results were reported by Gopalakrishnan et al.  in their carried out study.
Shirin et al.  found a positive correlation (r=0.581, P<0.01) between RI and serum creatinine and albuminuria, which indicates deterioration of renal function, that is, progression of the disease. Similarly, Afsar and colleagues and Mancini and colleagues also found a positive correlation between the albuminuria and renal RI ,,.
No statistically significant correlation was noted between the FBS and renal ultrasound parameters or RI values. Similar lack of statistically significant correlation was observed between FBS and restive index in a study done by Shaw and colleagues ,,.
The limitation of our study was the small sample size, so larger studies of a larger population may be essential to further assess the value of RI in patients with diabetic nephropathy and to obtain a better relationship with biochemical parameters and progression of disease processes.
| Conclusion|| |
Intrarenal RI measured by color Doppler ultrasonography has an important value in identifying diabetic patients who are developing nephropathy and can be used as an additional diagnostic tool in diagnosing diabetic nephropathy as well as to monitor progression of nephropathy.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3]