Dynamic three-dimensional MR renography for the measurement of single kidney function: initial experience

A three-dimensional magnetic resonance (MR) renographic method to measure single kidney glomerular filtration rate (GFR) and split renal function was developed that is based on renal signal intensity measurements during 2-3 minutes after intravenous injection of a low dose (2 mL or 0.01 mmol/kg) of gadopentetate dimeglumine. In nine subjects, single kidney MR GFR indices correlated well with technetium 99m (99mTc) diethylenetriaminepentaacetic acid (DTPA) clearance (r = 0.7-0.8) for GFR values of 7-48 mL/min. MR right kidney split renal function values (range, 32%-59%) also correlated well with 99mTc-DTPA radionuclide measurements (r = 0.76); differences between the two methods averaged 0.8% +/- 8. MR renography was performed along with contrast material-enhanced MR imaging of the kidneys and renal arteries and added 8 minutes or less to the total examination time.     

Increased kidney size following renal angioplasty. A 'new' observation

Percutaneous transluminal renal angioplasty was performed in nine patients (10 kidneys). Immediately following dilatation of the renal artery stenosis, seven of ten kidneys increased in length by at least 0.5 cm (0.5-1.5 cm) indicating improved renal perfusion. This is an observation that does not seem to have been described before. Another, but rare, cause of renal enlargement following angioplasty is hematoma formation which was seen in one of the cases. All of the patients responded well to the treatment and five previously hypertensive patients became normotensive shortly after dilatation.     

Estimation of pediatric skeletal age using geometric morphometrics and three-dimensional cranial size changes

This paper presents a method for estimating the skeletal age of children based on the centroid size of their face and their basicranium, derived from the three-dimensional coordinates of anatomical landmarks. The sample consists of computed tomography scans of 127 children (54 boys, 73 girls) of mixed origin living in the area of Toulouse (France), ranging in age from a few days to 18 years. The purpose of the present investigation was, first, to increase the variety of age-related structures theoretically available for pediatric skeletal age estimation and, second, to devise a method that can be applicable from early postnatal age to the end of adolescence with a satisfactory accuracy independent of age and even a better accuracy with greater age. We examined the relationship between the chronological age and the centroid size, calculated by using geometric morphometric methods and a linear model. With the aid of cross-validations, the statistical analysis indicates that the centroid size of the facial skeleton can be used an age-related variable without any loss of accuracy with increased age, contrary to most of the methods of pediatric age estimation. The standard error was always lower or equal to 2.1 years (at the 95% confidence level) and decreased in our sub-sample of older children represented by a larger number of individuals. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Percutaneous cryoablation of 40 solid renal tumors with US guidance and CT monitoring: initial experience

PURPOSE: To retrospectively determine the safety and effectiveness of percutaneous cryoablation, monitored with computed tomography (CT), for the treatment of solid renal masses. MATERIALS AND METHODS: This study was compliant with the Health Insurance Portability and Accountability Act and had institutional review board approval; informed consent was waived. From March 12, 2003, through August 4, 2005, 23 men and 17 women (mean age, 76 years +/- 9.7 [standard deviation]; range, 53-92 years), each with a single renal tumor, underwent one percutaneous cryoablation treatment session that combined ultrasonographic (US) guidance and CT monitoring. Technical success was defined as extension of the visible ice ball 5 mm beyond the tumor margin. Local tumor progression was defined as any tumor with intralesional enhancement or a serial increase in tumor size when compared with that on images obtained immediately after ablation. Tumor characteristics, complications, and follow-up were evaluated. RESULTS: The maximum diameter of the 40 treated lesions ranged from 1.5 to 7.2 cm (mean, 3.4 cm +/- 1.3). Twenty (50%) of 40 tumors were 3 cm or larger in diameter. Nineteen tumors (48%) extended into the renal sinus fat. One complication (2%) conformed to a grade 3 event, as determined with the Common Terminology Criteria for Adverse Events (version 3.0) of the National Cancer Institute; the overall complication rate was 8%. Thirty-eight (95%) of 40 cryoablation procedures were technically successful. Twenty-nine patients underwent follow-up (mean, 8.0 months +/- 4.3; range, 1.2-18.4 months); no local tumor recurrence was found. CONCLUSION: Percutaneous cryoablation with US guidance and CT monitoring is safe and effective for the treatment of solid renal tumors. Longer follow-up should provide further proof of the effectiveness of this technique.     

Fetal skeletal dysplasia: three-dimensional US--initial experience

PURPOSE: To compare the prenatal ultrasonographic (US) features of skeletal dysplasia by using two-dimensional (2D) and three-dimensional (3D) US to determine whether 3D US can reveal additional diagnostic information. MATERIALS AND METHODS: Seven pregnant women suspected of having skeletal dysplasia were examined by using 2D US and 3D US. Data regarding the thorax, spine, face, limbs, hands, and feet were compared. Multiplanar and volume-rendered US images were evaluated. RESULTS: The skeletal dysplasias studied included camptomelic dysplasia (n = 2), thanatophoric dysplasia (n = 1), osteogenesis imperfecta (n = 1), arthrogryposis (n = 2), and short-limbed dysplasia (n = 1). Three-dimensional US, by allowing review in a standard anatomic orientation, was better than 2D US in depicting abnormal spatial relationships such as short ribs, splayed digits, and absent bones. Three-dimensional US enabled the acquisition of additional information in two fetuses with facial abnormalities and in two fetuses with scapular aplasia or hypoplasia (one fetus had both facial and scapular anomalies); it enabled a specific diagnosis in one fetus. The archiving capabilities of 3D US allow the review and manipulation of data after the patient has left the clinic. CONCLUSION: In three of seven patients, 3D US provided additional information in the evaluation of skeletal dysplasias, as compared with 2D US.     

Angioplasty for pediatric renovascular hypertension: a 13-year experience

PURPOSE

We aimed to evaluate the long-term outcome and efficacy of percutaneous transluminal renal angioplasty (PTRA) for pediatric renal artery stenosis (RAS), which is an important cause of medication-refractory pediatric hypertension.

MATERIALS AND METHODS

We retrospectively evaluated 22 hypertensive children (age range, 3–17 years) who underwent PTRA from February 2000 to July 2012. Sixteen patients had Takayasu arteritis and six fibromuscular dysplasia. Five were not included in the statistical analysis due to loss to follow-up.

RESULTS

Technical success was achieved in 32 of 34 procedures (94.1%). The stenosis rate decreased from 84.5% before PTRA to 20.1% after PTRA. Treatment was effective in 72.7% (16/22) of patients, including complete cure in 27.3% (6/22) and improvement in 45.5% (10/22). Systolic and diastolic blood pressures decreased from 153±19.1 to 131.7±21.4 mmHg and from 97.9±14.2 to 83.6±19.3 mmHg, respectively (P < 0.01). Number of antihypertensive agents decreased from 2.7 to 0.5 per patient. Restenosis was detected in 40.9% (9/22) of patients, with a restenotic interval of 11.8 months (range, 3–47 months). Lesion length was strongly correlated with clinical success (cure and improvement) (independent-sample t test, P < 0.001; binary logistic regression, P = 0.040).

CONCLUSION

Lesion length is an important determination of clinical success with PTRA for pediatric RAS. PTRA is an appropriate treatment option for pediatric renovascular hypertension due to Takayasu arteritis and fibromuscular dysplasia.Although hypertension affects only 1%–2% of children and adolescents based on reliable assessments (1, 2), it is a major risk factor for cerebrovascular disease, myocardial infarction, and renal failure. Renal artery stenosis (RAS), a vascular disease, leads to 5%–25% of pediatric hypertension. Although a few conditions, including Kawasaki disease, polyarteritis nodosa, Wegener’s granulomatosis, neurofibromatosis, Williams syndrome, and midaortic syndrome, may cause RAS in pediatric patients (3, 4), Takayasu arteritis (TA) is the most common cause of pediatric RAS in the East, especially in China, Korea, and India (5, 6). Fibromuscular dysplasia (FMD) is another important cause of RAS in children, particularly in Western countries. A substantial proportion of patients with RAS suffer from hypertension and poor sequelae. Additionally, pediatric hypertension is strongly associated with hypertension in adults (7). However, blood pressure is not frequently measured in children. Due to the lack of sufficient information on blood pressure, renovascular hypertension is often ignored and/or diagnosed with a considerable time delay by referring physicians (5). Despite many antihypertensive agents, valid control of blood pressure is often impossible. Moreover, normalized blood pressure with multiple drugs may result in underperfusion of the kidney and cerebral blood vessels, thereby aggravating multiple organ dysfunction. Therefore, surgical interventions are considered as an alternative strategy to achieve an adequate control of blood pressure in pediatric patients (8).Here, we present 13 years of data on the outcomes of 22 children with renovascular hypertension caused by TA or FMD following treatment with a percutaneous transluminal renal angioplasty (PTRA) procedure.     

Percutaneous radiofrequency ablation of renal cell carcinomas in patients with solitary kidney: 6 years experience

Objective

In this study we attempt to present our clinical experience in RFA under CT-guidance, in patients with renal cell carcinoma in a solitary kidney.

Material and Method

Between October 2000 and June 2005, 18 patients with solitary kidney and renal cell carcinoma underwent percutaneous CT-guided radiofrequency ablation in our institution. Tumors diameter ranged from 1 to 7 cm and there was no evidence of spread beyond the kidney. The RFA-system used was with expandable needle electrode (7 or 9 arrays). Technical success, recurrence and survival rate and complications were accessed. Patients were available for clinical and laboratory evaluation at a mean follow-up time of 31.2 months (range: 12–72 months).

Results

In all cases the electrode was successfully placed at the lesion. The 18 tumors were treated with totally 24 RFA sessions. In small (1–3 cm) exophytic tumors technical success was 85.7%. Residual disease was totally seen in 6/18 tumors which required a 2nd RFA session. The recurrence rate was 11.1% but no recurrence was noticed in tumors less than 3 cm in diameter. No major complications were observed. Serum creatinine values were normal in 17/18 patients till the 3rd-month follow-up. Survival ranged from 12 to 72 months.

Conclusion

RFA is an acceptable alternative for patients with small RCCs in a solitary kidney, which are not ideal candidates for surgical resection as their renal function must be preserved. They have an immediate solution to their clinical problem, under a minimally invasive therapy with no serious complications.     

Pulmonary nodules: preliminary experience with three-dimensional evaluation

PURPOSE: To evaluate software designed to calculate pulmonary nodule volume in three dimensions. MATERIALS AND METHODS: Fifty-four solid noncalcified pulmonary nodules measuring 5-18 mm in diameter were studied with computed tomographic (CT) volumetric software. Baseline CT examinations were performed for various indications by using four-detector row multisection CT units, 1.25- or 2.50-mm sections, and a standard reconstruction algorithm. The percentage of successful nodule segmentations, as well as intraobserver variability, interreader agreement, and global repeatability of calculated volumes, was determined on the basis of consecutive measurements performed three times by three different radiologists by using the Bland and Altman method. The software was used to calculate the doubling time of 22 nodules for which a final diagnosis and comparable CT scans were available. RESULTS: Fifty-two (96%) of the 54 nodules were successfully segmented, allowing their volume to be calculated. Repeatability was high: There was no variation in the nine measurements of 35 (67%) of the 52 nodules. The coefficient of variation for the remaining 17 nodules (33%) was 2.26%. Bland and Altman 95% limits of acceptability, calculated on the basis of log-transformed data, yielded a maximum software measurement error of 6.38% of the previous volume measurement. Doubling time ranged from 4 to 188 years for the 13 benign nodules and from 37 to 216 days for the nine malignant nodules. CONCLUSION: Software volumetric analysis yielded repeatable estimates for 96% of the nodules examined. All software-calculated doubling times were in keeping with the benign or malignant nature of the nodules.     

Carotid arteries: contrast-enhanced US angiography--preliminary clinical experience

B-mode ultrasonographic (US) angiography enhanced with a microbubble-based US contrast agent (FS069) was evaluated in human subjects with carotid artery disease. Results at contrast material-enhanced US angiography and duplex US were compared with those at conventional angiography. Both US angiography and duplex US accurately depicted stenoses of 70% or more compared with those depicted at conventional angiography. The percentage diameter stenosis of the internal carotid artery measured at US angiography strongly correlated with that measured at conventional angiography (r = 0.988). The percentage area stenosis measured at US angiography strongly correlated with ex vivo measurements of the resected carotid plaque at magnetic resonance imaging (r = 0.979). US angiography depicted unsuspected wall irregularities, ulceration, and dissection.     

Hemodynamic investigation of the left renal vein in pediatric varicocele: Doppler US, venography, and pressure measurements

PURPOSE: To evaluate prospectively the hemodynamic state of the left renal vein with Doppler ultrasonography (US) and venography in pediatric patients with varicocele to assess the "nutcracker phenomenon." MATERIALS AND METHODS: The institutional review board considered this study ethically sound, and parental informed consent was obtained for all subjects. Doppler US of the left renal vein was performed in 27 consecutive boys with varicocele (age range, 7-15 years; mean, 11.9 years) and in 20 boys without varicocele as control subjects (age range, 7-17 years; mean, 11.4 years). Doppler US was used to evaluate left renal vein diameters and peak velocities in the proximal left renal vein near the renal hilum and in the left renal vein between the aorta and superior mesenteric artery (aortomesenteric portion). The diameter ratios and peak velocity ratios between two sites were obtained. For statistical comparison of results, the t test was used. Left renal venography and renocaval pressure measurement were performed in 13 patients with varicocele. The Fisher exact test was used to evaluate the associations between the nutcracker phenomenon (renocaval pressure gradient >/=3 mm Hg) and the development of collateral veins. RESULTS: The diameters of the proximal left renal vein and the peak velocities in the aortomesenteric portion of the left renal vein were significantly different between the varicocele group and the control group (P < .001). The diameter ratios (5.7 +/- 1.8 [standard deviation]) and peak velocity ratios (5.2 +/- 2.6) in patients with varicocele were significantly higher than those in control subjects (3.5 +/- 1.0 and 3.1 +/- 0.8, respectively) (P < .005). According to findings at left renal venography (n = 13), 10 patients (77%) met the criteria for the nutcracker phenomenon. The nutcracker phenomenon was significantly associated with the development of collateral veins (P = .035). CONCLUSION: Doppler US and venography of the left renal vein can show hemodynamic changes of the left renal vein and depict the presence of the nutcracker phenomenon in pediatric varicocele.     

Fetal lip and primary palate: three-dimensional versus two-dimensional US

PURPOSE: To determine if three-dimensional (3D) ultrasonography (US) improves the ability to define the location and extent of facial clefting prenatally compared with two-dimensional (2D) US. MATERIALS AND METHODS: Thirty-one fetuses suspected of having a facial cleft were examined prospectively with 2D and 3D US. Follow-up was performed in all fetuses. RESULTS: Twenty-eight fetuses had a cleft lip at birth. The location of the cleft lip was correctly identified in all fetuses with 3D US and in 26 of 28 with 2D US. Twenty-two fetuses had a cleft primary palate. Nineteen and nine of 22 cleft palates were identified by using 3D and 2D US, respectively. Three fetuses suspected of having a facial cleft at 2D US had a normal palate at 3D US and at birth. CONCLUSION: Three-dimensional US is useful to identify the location and extent of facial clefting. The advantages of 3D US are the following: (a) The face may be viewed in a standard orientation, (b) the defect may be viewed systematically by using an interactive display, and (c) the rendered image provides landmarks for the planar images. Patient decisions may be affected, since they can view the abnormality on a recognizable 3D rendered image.     

Vascular remodeling in atherosclerotic femoral arteries: three-dimensional US analysis

PURPOSE: To investigate the various modes of vascular remodeling of atherosclerotic femoral arteries and determine the associations between type of arterial remodeling and clinical data (age, sex, and medical history) and inflammatory parameters. MATERIALS AND METHODS: Intravascular ultrasonography (US) of the femoral arteries was performed in 50 patients with clinical symptoms of peripheral vascular disease. To determine the arterial remodeling mode (expansive remodeling [ER], involving compensatory enlargement of the artery, or constrictive remodeling [CR], involving vessel constriction during progression of atherosclerosis), the cross-sectional areas (CSAs) of the external elastic membrane (EEM), lumen, and plaque-plus-media were measured every 0.1 mm by using three-dimensional reconstruction. Clinical, laboratory, and intravascular US data were compared in the different remodeling groups (dominant ER, dominant CR, or mixed remodeling) by using analysis of variance supplemented by Tukey-Kramer tests. Multivariate analysis was performed to test independent variables predicting dominant ER. RESULTS: Intravascular US revealed the parallel existence of ER and CR in all patients: Increases and decreases in EEM in response to plaque growth could be observed within the same artery. ER dominated in 13 (26%) patients, and CR dominated in 11 (22%) patients: At least 80% of EEM CSAs were higher or lower than the mean of the EEM CSAs of the segments proximal and distal to the lesion. Patients with dominant ER had higher levels of serum C-reactive protein (CRP) compared with levels in patients with dominant CR and patients with mixed remodeling (1.62 mg/dL +/- 2.05 [standard deviation] vs 0.19 mg/dL +/- 0.33 and 0.21 mg/dL +/- 0.39, respectively, P < .005). Multivariate analysis revealed high CRP level to be a significant independent predictor for dominant ER (P < .01). CONCLUSION: The parallel existence of ER and CR was found in all patients with peripheral atherosclerosis, with a dominance of vessel expansion in 26% of patients. Higher plasma CRP level was associated with dominant ER.     

Cystic renal tumors: US and CT findings

Cystic renal tumors represent a variety of lesions in which both solid and liquid components coexist. These lesions may be either benign or malignant and include the multilocular cystic nephroma (MCN), the renal cell carcinoma (RCC), and the papillary adenocarcinoma (PAC). The MCN is a rare neoplasm formed of multiple loculated cystic masses divided by septa. The tumor is benign, although there are some rare reports of malignant cases. The RCC and the PAC may appear with cystic patterns. This is rather uncommon for the RCC, which inside has a unilocular or multilocular cystic appearance, if the necrotic component is large. PAC is an infrequent renal tumor, which has a greater tendency to appear as a large mass with a unilocular large cystic space. The ultrasonography (US) and computed tomographic (CT) features of 27 cystic tumors are presented. Both US and CT allowed the recognition of the cystic components, the septa, and the vegetations. The two imaging techniques made it possible to distinguish the tumors into “unilocular” and “multilocular” masses: the former correspond to RCC and PAC, the latter to MCN and RCC. CT added some information on calcified or partially calcified tumors. CT more than US enabled the differentiation between the malignant RCC and the benign MCN for which conservative surgery may be indicated. The two techniques did not allow the differentiation between RCC and PAC, which has different prognostic behavior.     

Bilateral renal lymphangiomatosis: US and CT findings

A case of bilateral renal lymphangiomatosis in an asymptomatic 50-year-old female is presented. Ultrasound and CT studies were performed. A finely septated fluid collection surrounding both kidneys and traversing the midline was found. Surgical biopsy was obtained and revealed findings compatible with lymphangiomatosis. A review of the literature of renal lymphangiomatosis is given. Received 24 October 1996; Revision received 10 February 1997; Accepted 11 March 1997