[Comparative ultrasound visualization of clinically relevant structures for evaluating the infant hip joint utilizing trapezoidal vs. parallel transducers].
OBJECTIVE
Sonographic evaluation of the infant hip joint according to the method of Graf has proven to be an important pediatric investigative instrument. Our goal was to investigate quantitatively whether (and in what ways) the clinically relevant infant hip joint structures visualize differently when utilizing trapezoidal as opposed to linear transducers. Our approach was both theoretical via a mathematical model and practical with in-vivo measurements in neonates.


METHODS
In a prospective study: 1. theoretical and computed analyses were performed for both linear and trapezoidal transducers regarding their respective accuracy for demonstrating the anatomic geometry of the infant hip, assuming not only correctly centered transducer positioning but also cases with off-centered displacement in the cranial or caudal direction; 2. both hip joints in 97 infants were examined by experienced investigators with comparison of the results for parallel vs. trapezoidal transducers.


RESULTS
Theoretical mathematical error analysis reveals no intrinsic systemic deviations between trapezoidal vs. parallel transducers in US scanning of the infant hip and furthermore no inherent disadvantages in the trapezoidal technique. Even when off-center transducer alignments of 1.5 cm are employed in the mathematical models, there is no significant relative distortion of the required anatomic structures when comparing the characteristics of both transducers. The practical in-vivo data from our 97 neonates confirmed the theoretical considerations.


CONCLUSIONS
No loss of accuracy or other negative factors are evident when trapezoidal transducers are used to visualize the infant hip joint in comparison with the customary parallel technique. There are no significantly measurable differences between the two approaches.
Wunsch
R
R
Abt. Pädiatrische Radiologie, Vestische Kinderklinik, Datteln. R.Wunsch@kinderklinik-datteln.de
Wegener-Panzer
A
A
Reinehr
T
T
Aurisch
E
E
Cleaveland
B
B
Wunsch
C
C
Dudwiesus
H
H
D042241:Early Diagnosis; D004867:Equipment Design; D005270:Femur Head / Q000000981:diagnostic imaging; D006618:Hip Dislocation, Congenital / Q000000981:diagnostic imaging; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D007231:Infant, Newborn; D008962:Models, Theoretical; D015997:Neonatal Screening; D012016:Reference Values; D012680:Sensitivity and Specificity; D014159:Transducers; D014463:Ultrasonography / Q000295:instrumentation*