The Accuracy of Pathological Evaluation for Tumor Necrosis in Post-chemotherapeutic Osteosarcoma by Using the Computer-designed Models

Abstract

The Accuracy of Pathological Evaluation for Tumor Necrosis in Post-chemotherapeutic Osteosarcoma by Using the Computer-designed Models

Damrong               Thapamakulsad    MD*

Pongsak                 Kagnarong            MD*

Nualsawat             Hiransakolwong   MD (Computer Science) **

Thawepong           Phithakmongkol  BS (Computer Science) **

*Department of Orthopaedic Surgery, BMA Medical College and vajira Hospital

** Department of Mathematics and Computer Science, Faculty of Science, King Mongkut's Institute of Technology Ladkrabang

Objective: To study the accuracy of pathological evaluation for tumor necrosis in post-chemotherapeutic osteosarcoma by  using the computer-designed models.

Study design: Experimental study by using the computer-designed models.

Setting: Department of Orthopaedic Suthery and Department of Pathology, BMA Medical College and Vajira Hospital and  Department Of Mathematics and Computer Science, Faculty of Science, King Mongkut's Institute of Technology Ladkrabang.

Subjects: 100 graphic models of osteosarcoma about 1066 cm. by size were classified to 4 groups. Each group consisted  of 25 graphic models represented 0-50%,50-90%,  90%  to  100%  and  100% of necrotic volume.

Methods: The imitations of pathological serial cross sections for 1, 1.5, 2, 3, 4, 5 cm intervals were created in all 100 graphic models. The average areas of necrosis in each group were calculated and compared with the true necrotic volume

Main outcome measure: The difference between average percentage of necrotic areas and necrotic volume.

Results: For 1 cm section, the differences between average necrotic areas and volumes in group 1-4 were 26.9%,4.2%, 0.4% and 0% respectively. The errors in clinical assessment were found in group 1, 2. For 1.5-5 cm section, the differences increased gradually especially in group 1, 2. The errors in clinical assessment were 2%, 2%, 4%, 8% and 8% in group 1, 2. and 2%, 0%, 2%, 0% and 0% in group 2, 4.

Conclusion: The regular using of 1 cm, section for pathological evaluation of tumor necrosis in post-chemotherapeutic osteosarcoma revealed the estimation errors especially in poor response group. On contrary, in good response group, these errors were less and the thickness of section from 1.5-5 cm did not affect the clinical assessment.

Key words: osteosarcoma, tumor necrosis, post-chemotherapy

Vajira Med J 2006 ; 50 : 27 - 32