The development of a pragmatic, clinically driven ultrasound curriculum in a UK medical school.

Whether ultrasound (US) should be incorporated into a medical undergraduate curriculum remains a matter of debate within the medical education arena. There are clear potential benefits to its early introduction particularly with respect to the study of living anatomy and physiology in addition to the learning of clinical skills and procedures required for the graduate clinical practice. However, this needs to be balanced against what is perceived as an added value in addition to financial and time constraints which may potentially lead to the sacrifice of other aspects of the curriculum. Several medical schools have already reported their experiences of teaching US either as a standalone course or as a fully integrated vertical curriculum. This article describes and discusses the initial experience of a UK medical school that has taken the steps to develop its own pragmatic vertical US curriculum based on clinical endpoints with the intent of using US to enhance the learning experience of students and equipping them with the skills required for the safe practice as a junior doctor.

Development of an anthropomorphic shoulder phantom model that simulates bony anatomy for sonographic measurement of the acromiohumeral distance.

The purpose of this project was to create a sonographic phantom model of the shoulder that was accurate in bone configuration. Its main purpose was for operator training to measure the acromiohumeral distance. A computerized 3-dimensional model of the superior half of the humerus and scapula was rendered and 3-dimensionally printed. The bone model was embedded in a gelatin compound and set in a shoulder-shaped mold. The materials used had speeds of sound that were well matched to soft tissue and epiphyseal bone. The model was specifically effective in simulating the acromiohumeral distance because of its accurate bone geometry.

Validation of ultrasound measurement of the subacromial space using a novel shoulder phantom model.

Ultrasound has a high degree of diagnostic accuracy in the assessment of rotator cuff tendons. Increasingly, ultrasound is being used to measure other parameters of rotator cuff pathology, including the size of the subacromial space, or acromiohumeral distance (AHD). Although this measure has been found to be clinically reliable, no assessment of its validity has been carried out. This technical study reports on the development of a novel ultrasound phantom of the shoulder and its use in validation of ultrasound measurement of AHD. There was a close agreement between AHD measures using ultrasound and the true subacromial space of the phantom model, providing support for the construct validity of this measurement. The phantom model has good potential for further development as a training tool for shoulder ultrasound and guided injections.

Reliability of aortic aneurysm screening measurements.

The aim of this feasibility study was to assess the impact that image processing of abdominal aortic ultrasound (US) images had on the intra-observer reliability of the diameter measurement. The study compared variability between inner-to-inner (ITI), outer-to-outer (OTO) and outer-to-inner (OTI) wall diameter measurements and their resilience to image processing. Three US images of transverse abdominal aortas were manipulated in 13 different ways using functions from Image J software (National Institutes of Health, Bethesda, MD, USA). Blinded measurements were performed of the aortic diameters from each image; this was repeated for ITI, OTO and OTI. Profiles of each image were produced and sets of rules developed to provide detailed instructions as to where, on the profile, the callipers should be placed to correspond with the actual image. The reliability of the diameter measurements compared to the original diameter measurement was least affected by adjusting the brightness and contrast of the US images (better than ± 1.5 mm). Using the functions 'Sharpen' and 'Find Edges' created the largest difference (up to -5 mm). The ITI measurements had the widest spread of variability, whereas the OTI measurements proved to be the most repeatable and resilient to image processing. This study suggests the precision of the measurements can be kept within satisfactory levels even after image manipulation. It also showed the most reliable measuring guideline was OTI, in contrast to the guideline currently used by the NHS Abdominal Aortic Aneurysm Screening Programme. Further research is needed to transfer the findings into the clinical setting of the National Screening Programme to increase its reliability.

Diagnostic ultrasound tooth imaging using fractional Fourier transform.

An ultrasound contact imaging method is proposed to measure the enamel thickness in the human tooth. A delay-line transducer with a working frequency of 15 MHz is chosen to achieve a minimum resolvable distance of 400 µm in human enamel. To confirm the contact between the tooth and the transducer, a verification technique based on the phase shift upon reflection is used. Because of the high attenuation in human teeth, linear frequency-modulated chirp excitation and pulse compression are exploited to increase the penetration depth and improve the SNR. Preliminary measurements show that the enamel-dentin boundary creates numerous internal reflections, which cause the applied chirp signals to interfere arbitrarily. In this work, the fractional Fourier transform (FrFT) is employed for the first time in dental imaging to separate chirp signals overlapping in both time and frequency domains. The overlapped chirps are compressed using the FrFT and matched filter techniques. Micro-computed tomography is used for validation of the ultrasound measurements for both techniques. For a human molar, the thickness of the enamel layer is measured with an average error of 5.5% after compressing with the FrFT and 13.4% after compressing with the matched filter based on the average speed of sound in human teeth.