Advances in three-dimensional diagnostic radiology

Role of single photon emission computerised tomography in evaluating osseointegration of indigenous DRDO implants: An in vivo study

BACKGROUND

A study of first indigenous titanium dental implant developed by DRDO was undertaken at INMAS, Delhi. The aim was to establish the time taken for osseointegration, along with objectives to define the time of implant loading and compare the osseointegration of indigenous dental implants with already established dental implant systems.

METHODS

21 subjects rehabilitated using 39 indigenous dental implants were evaluated by bone SPECT before implantation and at regular intervals towards establishing the aim and objectives.

RESULTS

The rise followed by fall in Osteoblastic activity indicates the postoperative physiologic changes, which peaked at 2 weeks (mean) post-implantation and falls off to pre-implantation levels in 12 weeks (mean) indicating completion of osseointegration, healing and time of loading.

CONCLUSION

It can be summarized that the Osteoblastic activity of indigenous dental implants completes within three months, which can be taken as the time required for complete healing/osseointegration and loading the implants. On comparison with the available data of already established implants the figures appear similar, indicating indigenous implants to be similar in biologic behaviour.

Integrated teaching of anatomy and radiology using three-dimensional image post-processing

This article presents a new way of teaching by integrating both anatomy and radiology using three-dimensional image post-processing tools. One preclinical and one clinical module were developed for integrated teaching of anatomy and radiology. Potential benefits were assessed by anonymous evaluation among the 176 participating students. The students highly appreciated the new approach, especially the high degree of interactivity with the post-processing software and the possibility to correlate the real dissection with the virtual dissection. Students agreed that three-dimensional imaging and postprocessing improved their understanding of difficult anatomical topics and topographical relations. We consider the new approach to provide great additional benefits for participating students regarding preparation for everyday clinical practice. In particular, it imparts familiarity with imaging and image post-processing techniques and may improve anatomical understanding, radiological diagnostic skills and three-dimensional appreciation.

Anatomy online: presentation of a detailed WWW atlas of human gross anatomy--reference for medical education

We present an online anatomy atlas based on the Visible Human Project (VHP) of the US National Library of Medicine. The objective is to provide original unlabeled as well as labeled sections of the human body of high quality and resolution on the Internet, for use in basic and continuing medical education. For a representative overview of the body, 370 axial sections were selected from the male and female data base of the VHP with special regard to regions of clinical interest. Each section is accompanied by its corresponding computer tomography (CT) image and, if available, magnetic resonance images (MRI) for quick and easy comparison of morphologic and radiologic structures. The sections can be studied unlabeled or labeled according to the current Terminologia Anatomica. A linked vocabulary with more than 850 terms explains the labeling. Animations of the sections as well as of CT and MR images allow for further visualization of the topographic relationships of anatomical structures. The responses to the project indicate that students and physicians regard the Internet Atlas of Human Gross Anatomy as a most useful aid for learning and reviewing anatomical details. The atlas is accessible on: http://www.uni-mainz.de/FB/Medizin/Anatomie/workshop/vishuman/Eready.html.

Computer-aided 3-D 99mTc-DPD-SPECT reconstruction to assess mandibular invasion by intraoral squamous cell carcinoma: diagnostic improvement or not?

OBJECTIVE

A prospective study was designed to compare computer-aided 3-D 99mTc-DPD-SPECT (Technetium-Dicarboxy propan-single photon emission CT) reconstruction with clinical examination, panoramic radiography, CT scan and conventional 99mTc-DPD-SPECT investigation in the assessment of mandibular bone invasion by squamous cell carcinoma.

PATIENTS AND METHODS

Between October 1997 and December 1999, 88 patients with intraoral squamous cell carcinoma of the regions adjacent to the mandible were enrolled in this study. In 50 cases, mandibular resection (segmental or marginal) was performed based on the pre-treatment diagnostic results. Imaging studies were read independently by four experienced observers.

RESULTS

No differences could be found between presurgical 3-D 99mTc-DPD-SPECT reconstruction and conventional 99mTc-DPD-SPECT investigation. Both techniques revealed a sensitivity of 100% whereas CT scan showed the greatest specificity (93.8%). SPECT investigation had a specificity of 91.6% and the greatest efficiency (95.4%). The greatest predictive positive value was found for CT scan (92.3%). Clinical examination and panoramic radiography displayed the lowest sensitivity, 82.5% vs. 85.0%, and specificity, 79.2% vs. 89.5% respectively.

CONCLUSION

This investigation does not provide evidence that 3-D 99mTc-DPD-SPECT reconstruction has any advantages when compared to conventional 99mTc-DPD-ECT investigation in the assessment of mandibular invasion by squamous cell carcinoma. Despite a sensitivity of 100% the specificity is still in need of improvement. Until newer methods or techniques become available the combination of CT scanning and conventional 99mTc-DPD-SPECT investigation appears to be the best means of detecting tumour invasion preoperatively and is thus helpful in directing appropriate surgical procedure.

Evaluation of microvascular bone graft reconstruction of the head and neck with 3-D 99mTc-DPD SPECT scans

OBJECTIVE

We conducted a prospective investigation to evaluate the diagnostic accuracy of computer-aided 3-dimensional (3-D) technetium 99m dicarboxypropane methylene diphosphonate ((99m)Tc-DPD) single photon emission computed tomography (SPECT) reconstruction in the evaluation of microvascular bone flaps used for maxillofacial reconstruction.

STUDY DESIGN

Twenty patients who received 20 autogenous microvascular bone flaps for reconstruction of the mandible and maxilla were evaluated. Forty bone scans with subsequent computer-aided reconstruction were performed. Each graft could be assessed within 48 to 72 hours after surgery. The second bone scan was performed between 12 and 14 days after surgery.

RESULTS

Complications were observed in 5 grafts. SPECT investigation performed at the 2 time points after reconstruction showed a significantly higher tracer uptake in grafts with an uncomplicated further course than in those that developed complications.

CONCLUSIONS

Computer-aided 3D (99m)Tc-DPD SPECT reconstruction serves as a useful prognostic tool and helps in the very early recognition of complications. This technique adds significantly to the value of planar bone scintigraphy and conventional SPECT images.

Using diagnostic radiology in human evolutionary studies

This paper reviews the application of medical imaging and associated computer graphics techniques to the study of human evolutionary history, with an emphasis on basic concepts and on the advantages and limitations of each method. Following a short discussion of plain film radiography and pluridirectional tomography, the principles of computed tomography (CT) and magnetic resonance imaging (MRI) and their role in the investigation of extant and fossil morphology are considered in more detail. The second half of the paper deals with techniques of 3-dimensional visualisation based on CT and MRI and with quantitative analysis of digital images.

The visible man: three-dimensional interactive musculoskeletal anatomic atlas of the lower extremity

A personal computer-based interactive musculoskeletal anatomic atlas of the lower extremity has been created by using the Visible Human Male data set. A semiautomatic segmentation program was developed by using an intelligent scissors approach and shape-based interpolation, thus considerably reducing the laborious work of the segmentation and labeling process. Manual contour extractions at 3-mm section intervals and shape-based interpolations of intervening sections of the musculoskeletal structures of the lower extremity were performed. For interactive and realistic three-dimensional display, an efficient binary volume rendering method was developed that introduces the concept of shear-warp factorization and applies a newly developed normal calculation technique. Binary volume rendering reconstructs various structures from a series of two-dimensional sections in a few seconds, thus enabling real-time manipulations of the computerized atlas. All of the muscles, tendons, and bones of the lower extremity have been segmented and labeled. The volume-based three-dimensional interactive atlas supports various interactions including rotation, removal, highlighting with artificial colors, arbitrary cutting operation, transparent view, and descriptive knowledge representation. In addition, browsing through the two-dimensional images of transverse, coronal, and sagittal views with labeling and segmentation information is possible.