BackgroundNormal ultrasound values for pole-to-pole kidney length (LPP) are well established for children, but very little is known about normal kidney size and its influencing factors in adults. The objectives of this study were thus to establish normal CT values for kidney dimensions from a group of unselected patients, identify potential influencing factors, and to estimate their significance.MethodsIn multiphase thin-slice MDCTs of 2.068 kidneys in 1.040 adults, the kidney length pole to pole (LPP), parenchymal (PW) and cortical width (CW), position and rotation status of the kidneys, number of renal arteries, pyelon width and possible influencing factors that can be visualized, were recorded from a volume data set. For length measurements, axes were adjusted individually in double oblique planes using a 3D-software. Analyses of distribution, T-tests, ANOVA, correlation and multivariate regression analyses were performed.ResultsLPP was 108.5 ± 12.2 mm for the right, and 111.3 ± 12.6 mm for the left kidney (p < 0.0001 each). PW on the right side was 15.4 ± 2.8 mm, slightly less than 15.9 ± 2.7 mm on the left side (p < 0.0001), the CW was the same (6.6 ± 1.9 mm). The most significant independent predictors for LPP, CW, and PW were body size, BMI, age, and gender (p < 0.001 each). In men, the LPP increases up to the fifth decade of life (p < 0.01). It is also influenced by the position of the kidneys, stenoses and number of renal arteries (SRA/NRA), infarctions suffered, parapelvic cysts, and absence of the contralateral kidney; CW is influenced by age, position, parapelvic cysts, NRA and SRA, and the PW is influenced in addition by rotation status (p < 0.05 each). Depending on the most important factors, gender-specific normal values were indicated for these dimensions, the length and width in cross section, width of the renal pelvis, and parenchyma-renal pyelon ratio.ConclusionsDue to the complex influences on kidney size, assessment should be made individually. The most important influencing factors are BMI, height, gender, age, position of the kidneys, stenoses and number of renal arteries.

OBJECTIVE To analyse the morphological appearance of horseshoe kidneys (HKs) and crossed fused ectopia (CFE) and to assess the frequency and clinical significance of associated anomalies and diseases. PATIENTS AND METHODS The findings and images of 209 patients with fused kidneys (FKs) were reviewed; in all, 244 scans from computed tomography (CT), 233 ultrasonograms and 89 micturition cysto‐urethrograms, urograms, magnetic resonance images and angiograms were taken. RESULTS HKs (found in one of 474 abdominal CT scans) and CFEs (found in one of 3078 CT scans) showed a high variability of vasculature that could not be classified. However, some generalized conclusions were possible about the renal vasculature (430 arteries in 103 kidneys). Variants of the most cephalad artery of both sides were rare. The second artery on the right had a pre‐caval course. The origins of vessels located further caudal were more ventral. CFEs were anatomically different from HKs with respect to lower position, greater axial rotation, smaller pelvic width, more caudal origin, and fewer vessels, but not in accompanying anomalies. Severe anomalies or malformations were found in 23% of patients, with half of them in the urogenital system. Malformations were found considerably more often in children than in adults. There was no increased incidence of diseases such as stones or inflammation of the renal pelvis. CONCLUSION Concomitant anomalies and diseases were equally frequent for HK and CFE, but less frequent than generally assumed. Individual cases of complex anatomical situations require special examination strategies, and CT appears to be the most reliable imaging method.

BackgroundDetection of risk factors for an air embolism in the left atrium, left ventricle, or systemic circulation (systemic air embolism, SAE) during a percutaneous core needle biopsy (PCNB) of the thorax.MethodsIn a retrospective observational study, all PCNBs of the thorax in 610 patients between 2007 and 2009 were analyzed. The SmartStep™ technique (General Electric) was used for the biopsy, with which the examiner can prepare a batch of three 1.25-mm or 2.5-mm collimated slices within a second using a foot switch in the CT room to check the needle position. The image data thus generated and the control CT scans that followed were examined retrospectively for the presence of intravascular air. Intravascular air was defined as two or more adjacent voxels with absorption values of < -200 HU in the left atrium, left ventricle, aorta, or arteries during or after the procedure. The univariate statistical analysis of categorical variables was made using 2 by 2 tables and the Fisher test. The groups were compared using the Mann-Whitney test. Finally, a multivariate logistic regression analysis was used to identify independent risk factors for the occurrence of an SAE.ResultsThe radiological incidence of an SAE during a PCNB was 3.8% (23/610 patients), whereas the clinically apparent incidence was 0.49%. Two patients developed clinical symptoms consisting of transient hemiplegia or transient amaurosis; one died due to a fatal SAE of the coronary arteries. The mortality was thus 0.16%. The depth of the needle in the lesion (Wald: 6.859), endotracheal anesthesia (Wald: 5.721), location of the lesion above the level of the left atrium (Wald: 5.159), and prone position of the patients (Wald: 4.317) were independent risk factors for the incidence of an SAE (p < 0.05 each). Using explorative criteria, the acute angle of the needle to the tumor surface, and the transition of ventilated lung were independent factors. The frequency of biopsies, needle penetration depth, and tumor location near the diaphragm or in the lower lobe also played a subordinate role, not however, the needle penetration depth through the lung.ConclusionIf possible, the PCNB should be performed under local anesthesia. We recommend avoiding endotracheal anesthesia and prone position. Whenever possible, patients should be positioned on the back in such a way that the tumor is lower than the left atrium. The tip of the needle should be within the tumor during the biopsy procedure.

Peripheral nerve tumors are not frequent, but due to their association with a nerve they are somewhat special. They may be encountered incidentally during evaluation of a soft-tissue mass or when a nerve lesion is clinically suspected and the recognition of such a lesion and its differential diagnosis is key for successful therapy and patient prognosis. As sonography is often the first line modality in the work-up of a soft-tissue mass, the sonographer should be aware of the typical features of such lesions in order to arrive at the correct diagnosis, and this article tries to give an overview of the histological subtypes of peripheral nerve tumors and their sonographic characteristics.

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