Computed Tomographic Angiography of the Abdomen and Pelvis in Azotemic Patients Utilizing 80-kV(p) Technique and Reduced Dose Iodinated Contrast: Comparison With Routine 120-kV(p) Technique.

OBJECTIVE: To evaluate image quality (IQ) of a reduced contrast volume, low kilovolt (peak) [kV(p)] abdominopelvic computed tomographic angiography (AP-CTA) protocol compared to a standard 120-kV(p) AP-CTA protocol. METHODS: A retrospective image analysis was performed on 103 patients with end-stage renal disease who underwent AP-CTA. Forty-nine patients were scanned at 80 kV(p) with a mean of 48 mL of contrast, and 54 patients were scanned at 120 kV(p) with a mean of 98 mL of contrast. Objective comparison of arterial attenuation, noise, and contrast-to-noise ratio was obtained, in addition to radiation dose. Subjective assessment of IQ, enhancement intensity, and image noise (IN) was scored on a 3-point scale. RESULTS: The 6-level aggregate contrast-to-noise ratio for the 80-kV(p) group was 11.8 ± 7.0, compared to 12.4 ± 4.6 in the 120-kV(p) group (P = 0.210). Radiation exposure was significantly lower in the 80-kV(p) group versus the 120-kV(p) group, as measured by average CT dose index (mGy) of 9.0 ± 3.1 and 15.8 ± 5.8 (P < 0.0001), respectively; and average dose length product (mGy × cm) of 490.0 ± 214.1 and 863.1 ± 344.4 (P < 0.0001), respectively. The 120-kV(p) technique scored better for subjective IQ (P = 0.042) and IN (P = 0.004) but not for enhancement intensity (P = 0.205). CONCLUSIONS: A 50% reduced iodinated contrast dose coupled with 80-kV(p) technique with iterative reconstruction allows for satisfactory AP-CTA studies at a 43% mean radiation dose reduction compared to a standard protocol. Negative but potentially reversible sequelae of this drop in radiation dose include increased IN and reduced subjective IQ.

Iodine contrast iso-attenuating with diagnostic gadolinium doses in CTA and angiography results in ultra-low iodine doses. A way to avoid both CIN and NSF in azotemic patients?

OBJECTIVES: To establish iodine (I) contrast medium (CM) doses iso-attenuating with gadolinium (Gd) CM doses regarded diagnostic in CTA and percutaneous catheter-angiography/vascular interventions (PCA/PVI) in azotemic patients. METHODS: CT Hounsfield units (HU) were measured in 20-mL syringes containing 0.01/0.02,/0.05/0.1 mmol/mL of iodine or gadolinium atoms and placed in phantoms. Relative contrast were measured in 20-mL syringes filled with iohexol at 35/50/70/90/110/140 mg I/mL and 0.5 M gadodiamide using radiofluoroscopy (RF), digital radiography (DX) and x-ray angiography (XA) systems. Clinical doses of Gd-CM at CTA/PCA/PVI were reviewed. RESULTS: At CT 91-116 and 104-125 mg I/mL in the chest and abdominal phantoms, respectively, were iso-attenuating with 0.5 M Gd at 80-140 kVp. At RF/DX/XA systems 35-90 mg I/mL were iso-attenuating with 0.5 M gadodiamide at 60-115 kVp. Clinically, 60 mL 91-125 mg I/mL (5.5-7.5 gram-iodine) at 80-140 kVp CTA and 60 mL of 35-90 mg I/mL (2.1-5.4 gram-iodine) at 60-115 kVp PCA/PVI would be iso-attenuating with 60 mL 0.5 M Gd-CM (=0.4 mmol Gd/kg in a 75-kg person). CONCLUSIONS: Meticulous examination technique and judicious use of ultra-low I-CM doses iso-attenuating with diagnostic Gd-CM doses in CTA and PCA/PVI may minimise the risk of nephrotoxicity in azotemic patients, while there is no risk of NSF.

Prediction of renal function improvement in azotemic patients using glomerular filtration rate from 99mTc-DTPA renal scan: An observational study.

ABSTRACT: This study aimed to evaluate the ratio of glomerular filtration rate (GFR) from 99mTc-diethylenetriamine-pentaacetic acid dynamic renal scan (GFRSCAN) to estimated GFR (eGFR) as a predictor of renal function improvement in patients with azotemia.A retrospective review of medical records was conducted to identify consecutive patients with newly discovered or aggravated azotemia who underwent 99mTc-diethylenetriamine-pentaacetic acid renal scan. Significant renal function improvement was defined as ≥100% and ≥10 mL/min improvement of eGFR at 12 weeks compared to eGFR on the day of renal scan (eGFR0). The GFRSCAN/eGFR0 ratio was evaluated as a predictor of significant renal function improvement using logistic regression and receiver operating characteristic (ROC) curve analyses. Added value of the GFRSCAN/eGFR0 ratio in the prediction of significant renal function improvement were demonstrated by adjusting for best clinical predictor variables.The eligibility criteria were met by 224 patients, among whom 22 patients (9.8%) showed significant renal function improvement. The odds ratios of the GFRSCAN/eGFR0 ratio for predicting significant renal function improvement were 1.76 (95% confidence interval [CI]: 1.26-2.45, P < .001) in the univariable analysis and 1.70 (95% CI: 1.19-2.42, P = .003) after adjusting for clinical variables. The area under the ROC curve of the GFRSCAN/eGFR0 ratio for predicting significant renal function improvement was 0.762 (95% CI: 0.648-0.871). The addition of the GFRSCAN/eGFR0 ratio to the best clinical prediction model raised the area under the ROC curve from 0.726 to 0.794, and this increment was statistically significant (P = .02).The GFRSCAN/eGFR ratio can predict renal function improvement in patients with azotemia. Future prospective studies are necessary to validate its potential clinical utilities.

Outcome after endovascular revascularization of atherosclerotic renal artery stenosis.

BACKGROUND: With an aging population, more patients might be treated for atherosclerotic renal artery stenosis (ARAS). The goal of this treatment is to achieve a dialysis-free life or a well-controlled blood pressure with reduced risks of cardiovascular complications. PURPOSE: To analyze the clinical outcome of percutaneous transluminal renal artery angioplasty without stenting (PTRA) or with stenting (PTRS) for ARAS at one center. MATERIAL AND METHODS: The study group comprised 152 patients who underwent 203 PTRA/PTRS. All had hypertension, and 45% had azotemia. A retrospective collection of baseline and postprocedural number of antihypertensive drugs, blood pressure, and serum creatinine were analyzed during a follow-up of 3-18 months. RESULTS: Technical success rate was 95%, and clinical benefit was seen in 63% of patients. Complications included a 30-day mortality rate of 1.5%, a total complication rate of 35%, and major adverse events in 13%. The major adverse events were highly related to azotemia. Major adverse events within 30 days, with permanent disability, were seen in 5% and almost exclusively in patients with moderate or severe renal impairment. A subgroup analysis of 28 patients with renal duplex resistive index (RI) pre-PTRA/S and 6 months' follow-up showed a benefit of PTRA/PTRS in 17 (68%) of the 25 patients with RI <80 and in all three (100%) of the patients with RI >or=80. CONCLUSION: Endovascular treatment of ARAS has an excellent technical success rate, with a clinical improvement rate of >60%. However, it is associated with a considerable complication rate. Serious complications are seen mainly in azotemic patients. Predictors of clinical response could not be identified. Renal duplex RI is questioned as a predictor of clinical outcome.

Comparison of ultrasonographic findings in cats with and without azotaemia.

Objectives The objective of this study was to identify the renal ultrasonographic (US) findings most strongly associated with azotaemia in cats. Methods US findings in 238 cats with (serum creatinine >180 µmol/l) and 270 cats without azotaemia were compared in a retrospective case-control study. Cats with pre-renal azotaemia or urethral obstruction were excluded. Data extracted from the medical records included age, body weight and body condition score (BCS). Quantitative and subjective US findings were extracted from archived ultrasound images and contemporaneous reports. Results In non-azotaemic cats, mean ± SD renal length was 40.1 ± 5.5 mm. Male cats had larger kidneys than female cats (mean difference 5.2 mm; P = 0.001) and, on average, the right kidney was slightly larger than the left (mean difference 1.6 mm; P = 0.01). Azotaemic cats had significantly lower mean body weight and BCS, and greater mean age and renal pelvic diameter. Renal pelvic diameter was negatively correlated with urine specific gravity (ρ -0.44, P <0.001). Compared with non-azotaemic cats, there was no difference in mean renal length of azotaemic cats because the numbers with enlarged kidneys and small kidneys were similar. Radiologists' subjective assessments of renal size differed markedly between azotaemic and non-azotaemic cats, with azotaemic cats more likely to be recorded falsely as having abnormally small or enlarged kidneys. US findings significantly associated with azotaemia were perinephric fluid (odds ratio [OR] 26.4, 95% confidence interval [CI] 3.4-207.7), small kidneys (OR 8.4, 95% CI 4.0-17.4), hyperechoic renal cortex (OR 4.1, 95% CI 2.2-7.6), loss of corticomedullary differentiation (OR 4.1, 95% CI 1.8-9.6), renal calculi (OR 2.7, 95% CI 1.4-4.9), enlarged kidneys (OR 2.5, 95% CI 1.2-5.5) and dilated renal pelvis (OR 1.6, 95% CI 1.3-1.9). Conclusions and relevance Perinephric fluid was the US finding most strongly associated with azotaemia in this study and may merit more emphasis than it has received to date. Bias in radiologists' subjective assessments of renal size suggests that other subjective findings will also be biased.

Renal resistive index in 55 dogs with degenerative mitral valve disease.

BACKGROUND: Azotemia occurs frequently in dogs with degenerative mitral valve disease (DMVD). It could indicate changes in renal hemodynamics. HYPOTHESIS/OBJECTIVES: To assess the renal resistive index (RI) in dogs with DMVD, and the statistical link between heart failure class, azotemia, echo-Doppler parameters, several plasma variables, and RI. ANIMALS: Fifty-five dogs with naturally occurring DVMD were used (ISACHC class 1 [n = 28], 2 [n = 19], and 3 [n = 8]). METHODS: Observational, blinded study, performed under standardized conditions. Physical examination, renal ultrasonography, and echo-Doppler examinations were performed in awake dogs. The RI of the renal, interlobar, and arcuate arteries were measured. Plasma creatinine, urea, and N-terminal pro-B-type natriuretic peptide concentrations (NT-proBNP) were determined. Statistical links between variables and RI were tested by means of a general linear model. RESULTS: Although the RI of renal and arcuate arteries were unaffected by ISACHC class, the left interlobar RI increased (P < .001) from 0.62 ± 0.05 (mean ± SD) in class 1 to 0.76 ± 0.08 in class 3. It was also higher (P < .001) in azotemic (0.74 ± 0.08) than in non-azotemic (0.62 ± 0.05) dogs. Similar findings were observed for right interlobar RI. Univariate analysis showed a positive statistical link between NT-proBNP (P = .002), urea (P < .001), creatinine (P = .002), urea-to-creatinine ratio (P < .001), left atrium-to-aorta ratio (P < .001), regurgitation fraction (P < .001), systolic pulmonary arterial pressure (P < .001), shortening fraction (P = .035), and RI. CONCLUSION AND CLINICAL IMPORTANCE: In dogs with DMVD, interlobar RI increases with heart failure severity and azotemia but a cause and effect relationship remains to be established.

Marrow visualization on renal scintigraphy: an often-overlooked finding in azotemic patients.

UNLABELLED: Delayed perfusion and enhanced hepatobiliary uptake are recognized findings on (99m)Tc-mercaptoacetyltriglycine ((99m)Tc-MAG3) scintigraphy in patients with renal insufficiency. Less well appreciated is the finding of bone marrow visualization. This study was performed to determine the frequency of this sign and to try to determine its association with laboratory parameters. METHODS: We retrospectively studied medical records and the results of renal scans performed on 170 patients from June to December 2009 at the Montefiore Medical Center. Among them we identified 167 patients who fulfilled our inclusion criteria for participation in this study. Prominent individual vertebrae and sacroiliac joints were categorized as bone marrow visualization. A lack of radiotracer activity in individual vertebrae or in the sacroiliac joints was categorized as bone marrow nonvisualization. The studies were interpreted by 2 nuclear medicine physicians who were unaware of the laboratory and clinical data. RESULTS: The 167 patients fulfilling our inclusion criteria were divided into 2 groups: group 1 (n = 20), with visualization, and group 2 (n = 147), without visualization. The mean creatinine level in group 1 was higher than that in group 2 (3.2 vs. 1.1, P = 0.001). There was no difference in mean hematocrit and hemoglobin between the 2 groups. None of the patients with a creatinine level less than 1.5 mg/dL had bone marrow visualization, whereas bone marrow was visualized in 44% of patients with a creatinine level greater than 1.5 mg/dL. There was no definite correlation between the intensity of marrow activity and the level of creatinine. CONCLUSION: Bone marrow often may be visualized on early images of (99m)Tc-MAG3 renal scans of azotemic patients. The etiology needs further clarification. Enhanced marrow perfusion, an increased blood concentration of (99m)Tc-MAG3, and marrow hyperplasia secondary to associated anemia or hemolysis are possible causes.

A case of end-stage renal disease initially manifested with visual loss caused by uremic optic neuropathy.

Uremic optic neuropathy (UON) is extremely rare, although sporadic cases have been reported. UON is sometimes regarded as a manifestation of uremic neuropathy. Here, we report a case of end-stage renal disease presenting as UON. A 22-year-old male was transferred to our nephrology department due to azotemia. Sudden deterioration of his vision occurred 3 days before his transfer. The patient's blood pressure was 150/90 mmHg, and he had no symptoms or signs of uremia, except for the visual disturbance. Blood tests showed an elevated serum creatinine of 6.0 mg/dL and serum BUN of 53.6 mg/dL. Both kidneys were decreased in size on ultrasound. His best-corrected vision was 20/62.5 in both the eyes. Ophthalmoscopy revealed hyperemia, swelling of both optic nerve heads, and blurred margins of both optic disks. These findings are compatible with UON. The patient's visual acuity and visual field improved following hemodialysis and corticosteroid treatment. The swelling of the patient's optic disks was also resolved. The patient is currently undergoing hemodialysis with the goal of vision restoration. Uremic optic neuropathy should be considered when patients with advanced chronic kidney disease complain of deterioration of their vision.

Thyroid stimulation with recombinant human thyrotropin in healthy cats, cats with non-thyroidal illness and in cats with low serum thyroxin and azotaemia after treatment of hyperthyroidism.

This study investigated the recombinant human thyrotropin (rhTSH) stimulation test in healthy cats (group 1), cats with non-thyroidal illness (group 2) and cats with low serum total T(4) (TT(4)) and azotaemia after (131)I treatment (group 3). Serum TT(4) responses and thyroidal pertechnetate uptake after administration of 25 microg rhTSH IV were assessed. Baseline serum TT(4) was significantly lower in group 3 compared with group 1, but not between other group pairs. Serum TT(4) increased significantly in groups 1 and 2 but not in group 3 after rhTSH administration. Post-rhTSH serum TT(4) concentrations differed significantly between groups 1 and 3 and groups 2 and 3, but not between groups 1 and 2. Thyroid/salivary gland uptake ratio (T/S uptake ratio) differed only significantly between groups 1 and 3. Stimulation with rhTSH is valuable to differentiate euthyroidism from iatrogenic hypothyroidism in cats.

Azotemia in cats with feline hypertrophic cardiomyopathy: prevalence and relationships with echocardiographic variables.

OBJECTIVES: The prevalence of renal azotemia in cats with acquired heart disease is not well documented. The aims of this study were therefore (1) to determine the prevalence of azotemia within a hospital population of cats with hypertrophic cardiomyopathy (HCM), and (2) to evaluate the relationship between echocardiographic variables and plasma urea and creatinine. ANIMALS, MATERIALS AND METHODS: 134 client-owned cats were retrospectively studied including 102 cats with HCM and 32 control cats. A complete physical examination, electrocardiography, systolic arterial blood pressure measurement, thoracic radiographs, and echocardiography were performed. Plasma creatinine and urea were determined in all cats. The animal was considered azotemic if plasma creatinine was >1.8 mg/dL and/or urea >65 mg/dL (i.e. BUN> 30 mg/dL). RESULTS: The prevalence of azotemia was lower in control cats (25.0%) than in cats with HCM (58.8%) (P=0.003). No significant differences in plasma urea and creatinine were observed between the HCM and control cats. There was no effect of plasma creatinine and urea on conventional echocardiographic variables in cats with HCM. CONCLUSIONS: Azotemia is a frequent finding in cats with HCM but is not dependent on echocardiographic variables.

Eighty-peak kilovoltage 16-channel multidetector computed tomography and reduced contrast-medium doses tailored to body weight to diagnose pulmonary embolism in azotaemic patients.

The aim of this study was to assess the feasibility of minimising contrast-medium (CM) doses using 80-peak kilovoltage (kVp) 16-channel multidetector computed tomography (MDCT) with CM dose tailored to body weight, when diagnosing pulmonary embolism (PE) in azotaemic patients. Twenty-nine patients (68-93 years; 38-79 kg) with an estimated glomerular filtration rate of 12-49 ml/min underwent 80 kVp MDCT at a median dose of 200 mg iodine (I)/kg and 15 s injection time. Pulmonary artery (PA) enhancement where compared with our own reference material using 320 mg I/kg at 120 kVp and with reported figures in the literature at 120-140 kVp and a 42 g iodine CM dose. Median (1st and 3rd quartiles) values regarding CM dose were 12.2 (9.9-12.8) g iodine; density of left main and lower lobe segmental PA 339 (275-395) Hounsfield units (HU) and 354 (321-442) HU, respectively. Those enhancement values were similar to those obtained from the reference population at 120 kVp and those reported in the literature at 120-140 kVp. One patient had a transient increase in plasma creatinine. Three months' follow-up revealed deep venous thrombosis among 1/18 patients with negative results from computed tomography (CT). We conclude that 80 kVp 16-channel MDCT to diagnose PE in azotaemic patients may be performed with markedly reduced CM doses, implying a lesser risk for CM-induced nephropathy.