Cryosurgery planning using bubble packing in 3D

Abstract

As part of an ongoing project to develop automated tools for cryosurgery planning, the current study focuses on the development of a 3D bubble packing method. A proof-of-concept for the new method is demonstrated on five prostate models, reconstructed from ultrasound images. The new method is a modification of an established method in 2D. Ellipsoidal bubbles are packed in the volume of the prostate in the current study; such bubbles can be viewed as a first-order approximation of a frozen region around a single cryoprobe. When all cryoprobes are inserted to the same depth, optimum planning was found to occur at about 60% of the length of the prostate (measured from its apex), which leads to cooling of approximately 75% of the prostate volume below a specific temperature threshold of −22°C. Bubble packing has the potential to dramatically reduce the run time for automated planning.

Key issues in bioheat transfer simulations for the application of cryosurgery planning

“…While the ratio of the volume below the planning isotherm to the volume of the frozen region is quite low at steady state (as also concluded in [3] for different cryoprobes), actual cryoprocedures are ordinarily terminated at the very early stage of the heat transfer process. In fact, several studies suggest that the number of cryoprobes should be increased in order to decrease the internal defect region, which can be concluded from the volume histograms in [7,9,11,12]; the termination of cryosurgery occurs earlier with the increasing number of cryoprobes. Without a target region and matching cryoprobe dimensions, termination of the freezing process remains hypothetical.…”

“…As an example, bubble-packing was demonstrated in an intra-operative mode [9], in which planning is modified after the localization of each cryoprobe, due to cryoprobe misplacement as a result of the insertion into the body. Very recently, this algorithm was demonstrated on the full 3D case [11]. In this context, while Magalov et al [3] selected a series of elementary layouts of up to three cryoprobes and investigated the resulting thermal history, the studies in [5][6][7]9,11] first set the target region and planning criteria, and only then let the computer code seek the best matching layouts for up to 14 cryoprobes.…”

“…the objective to provide results useful for understanding and designing the multi-cryoprobe procedure is commendable, critical evaluation of the Magalov et al [3] report must incorporate recent and relevant literature [4][5][6][7][8][9][10][11][12] not cited by these authors. (A few of the publications cited here were published only after [3] in archival journal, but are nonetheless relevant to the current discussion; those subjects have been widely presented in conferences in the past few years.)…”

Contemporary technique of intraoperative 3-dimensional ultrasonography–guided transperineal prostate cryotherapy

“…[21][22][23] It will then be possible to use 3DUS to guide focal therapies such as prostate cryotherapy, [24][25][26] which will be aided by automated computerized planning 27,28 and techniques such as 3D bubble packing. 29 Furthermore, cryotechnology is likely to continue improving, with smaller needles leading to decreased morbidity.…”

Numerical Prediction of the Intracellular ICE Formation Zone during Cryosurgery on a Nodular Basal Cell Carcinoma Using Liquid Nitrogen Spray

“…In Rossi et al [106] developed a numerical scheme for bioheat transfer simulations with application to phase change problems of cryosurgery using variable grid size and time intervals. Tanaka et al [107][108][109] developed an optimization method based on the bubble-packing and forcefield analogy methods to obtain the optimal arrangement of the cryoprobes during cryosurgical procedures. Maruyama et al [110,111] assessed a novel and rapid cooling system which employs a heat transfer control device based on the application of a thermoelectric principle (Peltier effect).…”