Compression of medical picture has acquired great attention attributable to its raising need to decrease the picture size while not compromising the diagnostically crucial medical data exhibited on the picture. The PCA algorithm may be used to help in picture compression. In this paper, a comparative study is provided for PCA and SPIHT compression method. Here the PCA algorithm is characterized in two forms, i.e. Standard PCA and Block-Based PCA. The block based PCA has 2 extended-PCA algorithms that manipulate the block data of the picture are evaluated. The first algorithm is referred to as block-by-block PCA where the standard PCA algorithm is utilized on every block of the picture. In the next algorithm- the block-to-row PCA, all of block data are initially concatenated into a row before the standard PCA algorithm is therefore utilized in the remodelled matrix. In this work, the SPIHT is being compared with the above two methods in terms of image quality and compression ratio. With this work, it is observed that block-based PCA performs superior to the PCA algorithm and SPIHT with regards to picture quality, producing a similar compression ratio like the PCA algorithm.