In the last 5 months, Dr. Warren has focused on the task of computing a lobe-based model for the lungs and developing a method for computing 3D warps between successive images in a 4D CT image. The culmination of this work is the recent completion of a joint paper between Dr. Warren and Dr. Guerrero, Lobe-based Estimation of Ventilation and Perfusion from 3D CT scans of the Lungs (Draft).

This paper describes a semi-automatic method for computing such a lobe-based model and constructing the desired 3D deformations between successive 3D CT scans of the lungs. Note here that the paper focuses only on semi-automatic methods that require some manual intervention by the radiologist. In our last progress report, we had hoped to construct fully automatic method for these problems. However, based on our efforts in December 2006-February 2007, we conclude that building a fully automated method that is robust in the presence of the type of data variant present in our test data was simply too ambitious in the short term.

Since generating plausible preliminary work is crucial for a successful NIH grant, we instead decided to focus on building semi-automatic methods in the short term. The goal of these methods would to construct the high-quality deformations necessary to assess whether ventilation and perfusion can be computed from 3D deformations between CT images. To this end, we have successfully constructed such deformation and developed a new, simplified mathematical model for computing ventilation and perfusion from this deformation.

Dr. Guerrero is enthusiastic about the quality of our results and feels that the paper has a chance at being accepted in a high-quality journal. We are currently deciding whether to submit the paper to a low-quality journal that has short turnaround or submit the paper to a higher-quality journal with longer turnaround. Our current thought is to probably submit to fast-turnaround journal and look to submit a proposal to NIH in June with the paper already accepted.

Dr. Zhang has also worked on developing an improved deformation method based on optical flow. In his latest paper, Compressible image registration for thoracic computed tomography images, Dr. Zhang has developed a 2D version of optical flow that is capable of modeling compressible flows (such as air flow in the lungs). Dr. Zhang’s graduate student have implemented this method and tested the method on pairs of 2D images of lung cross-sections. Based on favorable results from the 2D experiments, Dr. Zhang and his students are currently working on a 3D version of the method.

Our decision to delay submission of an NIH grant from February to June was also motivated by one more factor. Dr. Guerrero has asked Dr. Warren to participate as a co-PI in an NIH proposal to study assess the effectiveness of various drugs in mitigating the effects of radiation exposure. In particular, the aim of the proposal is to identify drugs that someone who has been exposed to a large dose of radiation (say as the result of the explosion of a “dirty” bomb) may take to mitigate the sometimes fatal damage to their small intestines from this radiation.

Although this topic does not directly address GC4R’s main topic of cancer research, Dr. Warren agreed to participate because he (and Dr. Guerrero) felt that this proposal had a high chance of success due to its relevance to Homeland Security. Based on advice from others who have been successful in pursuing NIH funding, we felt that having an established record of successful NIH funding would enhance our chances of eventually securing NIH funding for our lung project.