Multi-detector CT in the paediatric urinary tract.

The use of paediatric multi-slice CT (MSCT) is rapidly increasing worldwide. As technology advances its application in paediatric care is constantly expanding with an increasing need for radiation dose control and appropriate utilization. Recommendations on how and when to use CT for assessment of the paediatric urinary tract appear to be an important issue. Therefore the European Society of Paediatric Radiology (ESPR) uroradiology task force and European Society of Urogenital Radiology (ESUR) paediatric working groups created a proposal for performing renal CT in children that has recently been published. The objective of this paper is to discuss paediatric urinary tract CT (uro-CT) in more detail and depth. The specific aim is not only to offer general recommendations on clinical indications and optimization processes of paediatric CT examination, but also to address various childhood characteristics and phenomena that facilitate understanding the different approach and use of uro-CT in children compared to adults. According to ALARA principles, paediatric uro-CT should only be considered for selected indications provided high-level comprehensive US is not conclusive and alternative non-ionizing techniques such as MR are not available or appropriate. Optimization of paediatric uro-CT protocols (considering lower age-adapted kV and mAs) is mandatory, and the number of phases and acquisition series should be kept as few as possible.

ESPR uroradiology task force and ESUR paediatric working group: imaging recommendations in paediatric uroradiology, part IV: Minutes of the ESPR uroradiology task force mini-symposium on imaging in childhood renal hypertension and imaging of renal trauma in children.

Two new recommendations of the European Society of Radiology task force and the European Society of Uroradiology workgroup on paediatric uroradiology are presented. One deals with diagnostic imaging in children after trauma to the urinary tract-renal trauma, in particular. The other concerns the evaluation of suspected renal hypertension. Available data in the paediatric literature are either unsatisfactory or controversial for both of these clinical settings. Therefore, the following consensus-based proposals aim at outlining effective imaging algorithms to reduce invasive imaging procedures while optimising diagnostic accuracy. The objective of following a more uniform imaging approach is to facilitate future meta-analysis as well as multicentre and other more evidence-based studies. The practise in paediatric radiology is typically based on local availability and on the limitations of professional expertise and equipment, balanced against the perceived needs of the individual child. Although this is unlikely to change in the near future, it does not release the physicians in charge of diagnostic imaging from their responsibility in choosing and providing state-of-the-art imaging and management protocols that are adapted specifically for use in children.

[Whole-body MR imaging in children with suspected osteonecrosis after intensive chemotherapy: preliminary results]. / Ganzkörper-MRT bei Kindern mit Verdacht auf Osteonekrose nach intensiver Chemotherapie: Erste Ergebnisse.

PURPOSE: Use of multidrug chemotherapy poses the risk of avascular osseous necroses in children. Depiction of the whole body, including clinically non-apparent sites is mandatory for starting early and proper treatment, including surgical approaches in lesions near the joints. We analyzed the value of whole-body MRI in the detection of osteonecrosis, (1) in relation to conventional X-ray imaging and clinical symptoms, (2) using different MRI sequences, (3) with follow-up examinations. MATERIALS AND METHODS: 5 patients suffering from an oncological disease, 13 to 16 years old (3 x ALL, 1 x medulloblastoma, 1 x CML), and recently developing bone pain were examined with X-ray imaging of the particular region and a whole-body MRI (T2w TIRM, T 1w TSE sequences, pre- and post-contrast GD-DTPA, including fat suppression techniques). Neck/thorax/abdomen/pelvis, and upper and lower extremities were acquired in the coronal plane, and the feet in sagittal orientation. 4 of 5 patients had at least one follow-up examination (in the mean after 10 +/- 4 months). RESULTS: None of the initial X-ray images revealed an abnormal finding. The whole-body MRI showed in 4 of 5 children bone marrow lesions compatible with osteonecrosis. The locations were around the knee joints (n = 3) and the tibiae/ankle joints (n = 4). In addition to the symptomatic sites, MRI revealed additional lesions at the following sites: humerus (n = 5), hip joints (n = 4), knee joints (n = 6), ankle joints (n = 4). The size varied from small focal lesions to lesions measuring 90 % of the whole transverse diameter of the bone. The lesions were able to be detected most easily with heavily T 2-weighted (TIRM) sequences, and the diagnosis was most easily established using the non-enhanced TSE T 1-weighted sequences. As a consequence of the results of the whole-body MRI, all patients with lesions compatible with osteonecrosis received symptomatic (n = 2) or specific (n = 2) therapy. In the follow-up examinations, a higher number of patients showed no changes in the lesions as to size and distribution. 2 patients showed partial resolution of the osteonecroses. CONCLUSION: Whole-body MR imaging allows early diagnosis of symptomatic as well as clinically non-apparent osteonecroses. It can be used in planning and monitoring surgical and pharmacological therapies.

[Hypertensive crisis in infancy and childhood]. / Die hypertensive Krise im Kindes- und Jugendalter.

The extended physical examination of a patient includes measurement of blood pressure. In infancy and childhood the blood pressure measurement may be difficult due to an uncooperative and restless patient. In a 16-month-old girl apparently unmeasurable blood pressure was a hypertensive crisis with systolic blood pressure of more than 200 mmHg. The cause of the hypertension was found to be a nephroblastoma. In the case of rapidly progressive arterial hypertension in another 16-month-old girl with left ventricular dilatation and reduced function was a consequence of kidney dysplasia. Headache attacks lead to diagnosis of a subtotal coarctation of the aortic isthmus in a 17-year-old boy. Hypertensive crisis in infancy, childhood and adolescence is discussed based on these case reports. Special features of blood pressure measurement in the pediatric age group, pathogenesis of hypertensive crisis and the potential therapies are discussed incorporating a brief review of the literature.

[MR imaging and MR spectroscopy for characterization of cardiomyopathies in adolescents - preliminary results]. / MR-Bildgebung und MR-Spektroskopie zur Charakterisierung von Kardiomyopathien bei Jugendlichen - erste Ergebnisse.

PURPOSE: Cardiomyopathy is a rare but life-threatening disease in children and adolescents. Recent studies reported morphological, functional or metabolic alterations of the heart. We discuss a combined MR imaging and (31)P MR spectroscopy (MRS) protocol allowing the analysis of interdependencies between these parameters. Since normal values of cardiac MR parameters in this age group are not available, we included studies of age-matched healthy adolescents. MATERIALS AND METHODS: 2D-CINE was used to assess left ventricular (LV) parameters. Additional 3D-Chemical Shift Imaging (3D-CSI) and Spectral Localization with Optimal Pointspread Function (SLOOP) reconstruction allowed quantification of the cardiac energy metabolism. Patients (n = 4; all male; age 16.8 +/- 2.9 years) were included on the basis of an echocardiographic diagnosis of possible cardiomyopathy. The same protocol was applied to healthy young volunteers (n = 4; 1 female, 3 male; age 15.5 +/- 0.6 years). RESULTS: The patients had a significantly higher LV mass index compared to the control group (147 +/- 41 g/m (2) versus 97 +/- 16 g/m2; p = 0.04). The other LV parameters (including LV EF with 59 +/- 22 % versus 67 +/- 10 %) showed no significant differences. The phosphocreatine to adenosine triphosphate ratio (PCr/ATP-ratio) of the patients was reduced to 1.71 +/- 0.40 versus 2.44 +/- 0.30 (p = 0.01), combined with a tendency towards decreased PCr concentrations of 9.1 +/- 2.5 versus 7.9 +/- 1.0 mmol/kg. CONCLUSION: The combination of (31)P MR spectroscopy and MR imaging allows quantitative determination of morphologic, functional and metabolic alterations in adolescents with suspected cardiomyopathy in one examination procedure. The reduction of energy metabolism combined with unaltered global function may indicate a primary role of metabolism in the pathogenesis of cardiomyopathies in adolescents.

[In-vitro comparison of a 1st and a 2nd generation US contrast agent for reflux diagnosis]. / In-vitro-Vergleich eines Ultraschallkontrastmittels der 1. mit einem der 2. Generation für die Refluxdiagnostik.

PURPOSE: Contrast-enhanced sonographic reflux diagnosis, i. e. voiding urosonography (VUS), is gradually becoming an alternative for diagnostic imaging of vesicoureteric reflux (VUR). A limiting factor for the widespread application of VUS is the cost of the US contrast agents. The development of new US contrast agents and the possibility of reducing the administered dose are expected to lower the cost. The aim of this study was an in-vitro comparison of the new US contrast agent (SonoVue) and the routinely used contrast agent Levovist, while taking into consideration the physical-chemical properties relevant for reflux diagnosis. MATERIALS AND METHODS: The in-vitro experiment setup simulated the in-vivo VUS. The US modalities fundamental and harmonic imaging (THI/ECI, Sonoline Elegra, Siemens) were utilized, the latter with both low and high mechanical indices (MI). SonoVue was tested in concentrations of 0.25 %, 0.5 % and 1 % and Levovist at 5 % volume. The in-vitro contrast duration served as the parameter for comparison. This was defined as the time from the start of the experiment until the time when more than 50 % of the image area was free of microbubbles. RESULTS: The use of different concentrations of SonoVue did not have any impact on the contrast duration. The contrast duration of SonoVue turned out to be significantly longer when the US modality was switched from low to high MI. In the case of THI with high MI as is routinely with Levovist, the contrast duration of Levovist at a concentration of 5 % was 1.1 min, whereas that of SonoVue at a concentration of 1 % reached 7.3 min. This means that despite SonoVue being administered at a dose five times lower than that of Levovist, the in-vitro contrast duration increased by more than 80 %. Moreover, a freshly prepared suspension of SonoVue did not show change in the contrast duration for nearly 6 hours. In the case of Levovist there was a significant reduction in the contrast duration after only a half hour. CONCLUSION: The in-vivo use of SonoVue is expected to yield a significant dose reduction so that one vial can be used for more than one examination. A measurable cost reduction can consequently be achieved.

[Diagnosis of appendicitis using harmonic ultrasound imaging]. / Sonografische Diagnostik der Appendizitis bei Kindern - Verbesserte Darstellung mittels Harmonic Imaging.

INTRODUCTION: Harmonic Imaging (HI) is a new Ultrasound (US) modality with high contrast and spatial resolution. Aim of this study was to compare fundamental imaging (FI) and HI in the diagnosis of appendicitis. PATIENTS AND METHODS: In 50 children (male : female, 25 : 25; mean age: 9.9 years) prior to an appendectomy US of the right lower quadrant was performed in both FI and HI (Tissue Harmonic Imaging - THI - Sonoline Elegra, Siemens, 7.5 MHz linear). The images were compared with respect to delineation of surrounding, contour, wall and content of the appendix. RESULTS: In 43 / 50 (86 %) patients diagnosis of appendicitis was confirmed histologically (sensitivity 98 %, specificity 94 %). In 37 / 43 patients the appendix was depicted using FI. With HI this number was 40 / 43. HI was significantly better in delineating the contour, wall, mucosa and content of the appendix (p < 0.01). HI also exceeded in demonstrating free fluid, mesenterial lymph nodes and surrounding echogenicity. CONCLUSION: HI of appendicitis provides images with significantly better quality than FI. When both imaging options are available harmonic imaging modality should be the preferred choice for scanning the appendix.

[Radiographic changes in non-operated isolated sagittal suture synostosis]. / Radiologische Veränderungen bei nichtoperierter isolierter Sagittalnahtsynostose.

PURPOSE: To characterize the spontaneous clinical course of isolated sagittal synostosis based on planar skull radiography. MATERIALS AND METHODS: In this retrospective analysis we evaluated a total of 155 radiographs of 55 children 2 weeks to 9 years old. The sagittal, coronal and lambdoid sutures were evaluated on the basis of pairs of ap and lateral radiographs. The sutures were examined with respect to their boundary, activity, and conspicuity to be visualized (based on a 3-grade score system). Six selected points on the skull X-ray defined eight measured distances, three angles, and a width-length index. To document changes over time, the measurements were correlated to normal values. In addition, a correlation between suture activity and selected parameters was evaluated. RESULTS: The sagittal suture could be continuously or partially depicted in more then half of all radiographs taken during the first year of life, The measured distances and angles were concordant with results from the literature. With increasing age, the width-length index deviated from standard values while other parameters approximated the norm. CONCLUSION: In the case of children younger than twelve months, the sagittal suture appears radiologically open in many cases despite clear-cut scaphocephaly. Definite signs of progressive plurisutural fusion were not found in this series. The dolichocephalic deformity remained unchanged while some signs of scaphocephalic appearance actually improved.

[Ectopic ureter with urinary dribbling in childhood -- a diagnostic challenge: our own experience and review of the literature]. / Ureterektopie mit Harnträufeln im Kindesalter -- eine diagnostische Herausforderung : Eigene Erfahrungen und Literaturübersicht.

Based on the observations in four girls suffering from constant urinary dribbling we analyzed the special features and difficulties in making the diagnosis of an ectopic ureter. In all patients there was marked diagnostic delay. In one symptomatic case the abnormality was not detected before the age of 18 years. Failure to recognize the characteristic signs and symptoms played a crucial role in delaying the diagnosis. Moreover, imaging of ureteral ectopia represents a diagnostic challenge. The ectopic ureters were associated with dysplastic, poorly functioning renal moieties. Common diagnostic imaging procedures, such as ultrasound, intravenous pyelography, or voiding cystourethrography yielded incomplete diagnostic information and often failed to provide a definitive diagnosis. The latter could only be obtained with MR urography. We assessed the diagnostic value of the different examinations and compared our findings with those reported in the literature.

[Modern ultrasound technologies and their application in pediatric urinary tract imaging]. / Moderne Ultraschalltechniken und ihre Anwendungen am kindlichen Harntrakt.

In children ultrasound plays a central role in the diagnostic imaging of the urinary tract. It is used most frequently and as a primary diagnostic option. Consequently, innovations in ultrasound technology and ultrasound contrast media have major impact on pediatric urosonography. Harmonic imaging is a modality that produces artifact-free images with high resolution. It has been shown that harmonic imaging is superior to fundamental mode in many urosonographic indications. Color Doppler is an established imaging modality, but its application for diagnosis of stones in the urinary tract, especially in children, is relatively new. The so-called twinkling sign, a color Doppler artifact at the site where one normally expects the acoustic shadow to be, enhances the conspicuity of the stone. A further development is three-dimensional (3D) ultrasound. It offers better volume measurement of the bladder and kidneys than 2D ultrasound. Contrast-enhanced voiding urosonography has already proven to be a valuable alternative in the diagnosis of vesicoureteral reflux. Thus, a significant decrease of radiation exposure has become possible as it replaces the radiological methods. With the introduction of contrast-specific ultrasound imaging modalities, further improvements in voiding urosonography are emerging.

[Aseptic meningitis after intrathecal infusion of a parenteral nutrition solution: examples of rare malpositions of central venous catheters in preterm neonates]. / Aseptische Meningitis nach intrathekaler Infusion einer parenteralen Ernährungslösung: Beispiele seltener Fehllagen zentraler Venenkatheter bei Frühgeborenen.

BACKGROUND: Central venous catheters are an indispensable part of intensive care. In the management of preterm neonates, these are introduced after puncture of a peripheral subcutaneous vein. The catheters are supposed to be pushed forward with the venous flow. A chest X-ray is usually performed for verification of the position of the catheter. Localization of the tip of the catheter is often very difficult because of its extremely small diameter. METHODS: A malposition of a central venous catheter resulting in intrathecal infusion of parenteral nutrition and subsequent aseptic meningitis in a preterm neonate is presented. Further cases of catheter malpositions leading to arthrography, arteriography and incorrect position in various parts of the venous system are discussed. DISCUSSION AND CONCLUSION: The case reports demonstrate that wire-guided central venous catheters are not only advanced by the forward blood flow but can also inadvertently end up in undesired sites and may thus induce serious side effects.

Progressively enlarging pericardial lipoma in a child.

Mediastinal lipomas are slowly growing tumours. Only very few cases have been reported in children. None of these included a rapidly enlarging lipoma. We present an 8-year-old severely adipose girl with an incidentally diagnosed mediastinal lipoma that showed rapid enlargement within 7 weeks.

[Advances in pediatric sonography]. / Fortschritte in der pädiatrischen Sonographie.

Advances in the field of ultrasound technology and ultrasound contrast media over the past few years have also brought major improvements to pediatric sonography. Accordingly, contrast-enhanced voiding urosonography has become a valuable alternative in the diagnosis of vesicoureteral reflux. It is possible to achieve significant reduction in radiation exposure replacing the conventional radiologic methods used for reflux diagnosis with contrast-enhanced ultrasound. Through the introduction of harmonic imaging, an ultrasound scanning modality with high spatial and contrast resolution has become available. The modality was initially propagated as one to be applied in difficult-to-scan adults. However, initial experiences in pediatric applications are demonstrating the significant improvement it can bring in the ultrasound image quality, for example, in intestinal ultrasound. A further development is three-dimensional [3D] imaging using ultrasound. 3D-ultrasound not only offers an improvement in diagnosis but also in the acceptance of ultrasound in interdisciplinary work and teaching. The first applications of 3D-ultrasound in pediatrics are focusing on brain ultrasound and volume measurement of the kidneys.

Simultaneous voiding cystourethrography and voiding urosonography.

PURPOSE: To compare the diagnostic accuracy of contrast-enhanced voiding urosonography (VUS) and voiding cystourethrography (VCUG) during simultaneous performance of both examinations. MATERIAL AND METHODS: A total of 24 children, 16 girls and 8 boys, with a mean age of 3.5 years referred for reflux examination were recruited for the study. After transurethral bladder catheterization, radiographic contrast medium, followed directly by the US contrast medium, were administered. Fluoroscopic VCUG and VUS were carried out concurrently in the same patient. When 1 kidney was scanned by ultrasound, fluoroscopy was performed on the contralateral side. RESULTS: In 19 of the 47 kidney-ureter-units (KUU) vesicoureteral reflux (VUR) was detected. In 16 units the reflux was detected by both VCUG and VUS. In 3 KUUs the reflux was detected only at VCUG. All 3 cases were grade 1. Taking the VCUG as the reference standard, VUS had 84% sensitivity, 100% specificity, 100% and 90% positive and negative predictive values, respectively. CONCLUSION: A dependable comparison could be achieved by performing VCUG and VUS at the same time and under the same conditions. It reconfirmed that VUS is reliable in the exclusion or verification of reflux.

Reduction in voiding cystourethrographies after the introduction of contrast enhanced sonographic reflux diagnosis.

BACKGROUND: Voiding urosonography (VUS) using the intravesical application of an US contrast medium (Levovist) has been shown to have very high sensitivity and specificity in the diagnosis of vesicoureteric reflux (VUR) compared to voiding cystourethrography (VCUG). OBJECTIVE: To determine the extent of reduction of VCUGs after adding VUS to the diagnostic algorithm of VUR. MATERIALS AND METHODS: Over 2 years, 449 children (162 boys, 287 girls) were referred for diagnosis of possible VUR. The selection of a particular reflux examination was based on pre-defined criteria. VUS was performed primarily in girls and follow-up cases. The indications for VCUG were as follows: (a) boys - first examination for VUR, (b) specific request for urethra or bladder imaging, (c) girls - when VUR was diagnosed in the VUS and no VCUG had been done previously, and (d) inadequate VUS. RESULTS: VCUGs were primarily carried out in 141 cases. VUSs were performed in 308 patients. In 69 of these patients a VCUG followed during the same examination session. Thus 239 of 449 patients underwent only VUS, resulting in reduction of the VCUGs by 53 %. CONCLUSIONS: The number of VCUGs was significantly reduced as a result of the implementation of VUS as part of the routine diagnostic imaging modality for VUR. Consequently, the number of children that would have been exposed to ionising radiation was reduced by over half.

Contrast-enhanced harmonic imaging for the diagnosis of vesicoureteral reflux in pediatric patients.

OBJECTIVE: Harmonic imaging using phase or pulse inversion technology is a new sonographic diagnostic modality that has the potential to produce images of a higher quality than can be obtained with the conventional method. The aim of this study was to compare both types of harmonic modalities--tissue and contrast harmonic imaging--with the fundamental imaging mode in contrast-enhanced B-mode sonographic diagnosis of vesicoureteral reflux. SUBJECTS AND METHODS: Fifty-four children presenting for diagnostic examination of vesicoureteral reflux underwent standard sonography of the urinary tract in the fundamental mode, followed by intravesical administration of a galactose-based contrast medium containing microbubbles. The contrast-enhanced sonography was conducted by scanning the bladder and each kidney in transverse and longitudinal planes, from ventral and dorsal views, consecutively in B-mode using fundamental, contrast harmonic, and tissue harmonic imaging modalities. Soft-touch buttons on the console screen were used to alternate between the three imaging options, so that switching from one modality to the other could be done almost instantaneously. For comparison, in each patient, we selected one set of contrast-enhanced images of the bladder and two sets, one ventral and one dorsal, of the kidney. In a series, the images were compared and ranked from 1 to 3, with 1 being the best, with regard to sonomorphology (demarcation of the retrovesical space and renal pelvis as the potential sites to look for vesicoureteral reflux) and reflux detection and conspicuity, if present. RESULTS: In all, 248 sets of images were available for comparison. The delineation of both the retrovesical space and the renal pelvis was found to be best with tissue harmonic imaging in 84% and 96% of the image sets, respectively (p < 0.01). Forty-one sets of images were compared from 27 kidney-ureter image units of 22 children (41%) with reflux. The refluxing microbubbles were much more conspicuous in the harmonic imaging mode (tissue harmonic, 100%; contrast harmonic, 93%) than in the fundamental mode (p < 0.01). In eight kidney-ureter units, the reflux was detected only by using the harmonic imaging modalities. CONCLUSION: Visualization of the urinary tract and detection of ultrasound contrast media is significantly improved by the use of the harmonic imaging modalities. When both fundamental and harmonic imaging options are available, we recommend harmonic imaging for contrast-enhanced sonographic diagnosis of vesicoureteral reflux.

[Acute hematogenous osteomyelitis--exclusion with Turbo-STIR sequence?]. / Akute hämatogene Osteomyelitis--Ausschluss mit Turbo-STIR-Sequenz?

The timely diagnosis and early initiation of antibiotic therapy determine the clinical course of an acute hematogenous osteomyelitis. Consequently, a fast and efficient MRI examination protocol is crucial. We retrospectively evaluated various MR sequences used in the examination of 8 children having osteomyelitis. The examinations were conducted using a 0.5 T MR machine. All patients had a high signal intensity of the lesion in the IR sequence with fat suppression (turbo-STIR). An acute osteomyelitis can be excluded in the absence of signal intensity increase in the turbo-STIR sequence without the necessity of having to perform additional sequences.

Internal jugular venous valves in children: high-resolution US findings.

The aim of this study was to determine in children the prevalence rate and to describe the sonographic morphology of the valves in the internal jugular veins. One hundred twenty children (60 boys and 60 girls; mean age +/- SD 10 +/- 4 years, age range 3-20 years) were recruited for the study. They underwent sonographic examination of both internal jugular veins. The number of valvular cusps, the length of the cusps and exact site of origin were recorded. In 96% of the children a valve was found in one or both internal jugular veins. Within this group a valve was detected unilaterally in 26% and bilaterally in 74% of the cases. Ultrasound morphological and morphometric analysis was carried out in a total of 239 internal jugular veins; 200 (84%) veins were found to have valves. The origin of the cusps was located at a mean distance of 9 mm (0-26 mm) proximal to the confluence of the subclavian and internal jugular veins into the brachiocephalic vein. A valve in the distal part of the internal jugular vein is a very common finding with characteristic features on US.

[Static-dynamic MR urography. Comparison with excretory urography and scintigraphy in experimentally-induced urinary tract obstruction]. / Statisch-dynamische MR-Urographie. Vergleich mit Ausscheidungsurographie und Szintigraphie bei experimentell induzierter Harntransportstörung (HTS).

PURPOSE: To assess the diagnostic value of combined static-dynamic MR urography (MRU) for the functional-morphological evaluation of experimentally induced urinary tract obstruction. METHODS: Static-dynamic MRU--combination study with a respiratory-triggered 3D-IR-TSE sequence and a dynamic 2D-FFE sequence after Gd-DTPA and furosemide--was obtained in comparison with 99mTc-MAG3 diuretic renal scintigraphy (DRS), excretory urography (EU) and ultrasound (US) in 29 healthy piglets and in 20 piglets with surgically induced ureteric stenosis (total of 50 postoperative examination blocks). RESULTS: MRU allowed complete depiction of the urinary tract in all controls, in operated piglets the stenosis was always correctly identified. Quality of MRU was superior to EU in 36 of 43 comparative studies. Calculation of single kidney function from parenchymal renograms, and assessment of urinary excretion from whole-kidney renograms resulted in a highly significant agreement of MRU with DRS. CONCLUSION: Static-dynamic MR urography allows excellent depiction of experimentally induced urinary tract obstruction, and reliable assessment of individual renal function and urinary excretion. Two advantages of the method stand out, it does not require radiation and it permits a functional-morphological correlation.