Aashish D. Bhatt

Current and emerging concepts in non-invasive and minimally invasive management of spine metastasis

To provide a comprehensive review on the presentation, work-up and the management of spine metastasis with or without epidural spinal cord compression with focus on the roles of surgery and radiotherapy. Emphasis has been laid on the technological advances with recent development of stereotactic body radiotherapy (SBRT) or radiosurgery (SRS) and minimally invasive surgical approaches like kyphoplasty and vertebroplasty.

Tumor volume change with stereotactic body radiotherapy (SBRT) for early-stage lung cancer: evaluating the potential for adaptive SBRT.

Objectives:To quantify gross tumor volume (GTV) change during stereotactic body radiotherapy (SBRT) and on first follow-up, as well as to evaluate for any predictive prognostic risk factors related to GTV decrease. An attempt was also made to identify the potential timing for adaptive SBRT. Methods:Twenty-five tumors in 24 consecutive patients were treated with SBRT to total dose of 50 Gy in 5 fractions. Median age was 72.5 years. Tumor stage was T1, 68%; T2, 20%; and other, 12%. The GTVs of on the 5 cone-beam computed tomographies (CBCT1-5) obtained before each fraction and the first follow-up CT (CTPOST) were analyzed. Results:Median time from diagnosis to initiation of radiotherapy was 64 days. GTV on CBCT1 was the baseline for comparison. GTV decreased by a mean of 7% on CBCT2 (P=0.148), 11% on CBCT3 (P=0.364), 19% on CBCT4 (P=0.0021), and 32% on CBCT5 (P=0.0004). Univariate analyses of GTV shrinkage was significantly associated with “time from CBCT5 to CTPOST” (P=0.027) and “T-stage” (P=0.002). In multivariate analyses, “T-stage” remained significant with T1 tumors showing greater GTV shrinkage than T2 tumors. Conclusions:Significant decrease in GTV volume based on daily CBCT was demonstrated during SBRT treatment. Adaptive SBRT has the potential to minimize integral dose to the surrounding normal tissues without compromising GTV coverage.

Role of nuclear medicine imaging in recognizing different causes of osteonecrosis of the jaw.

The incidence of osteonecrosis of the jaw (ONJ) among patients with cancer and metastatic bone disease being treated with bisphosphonates is as high as 10%, which dictates that an understanding of the risk factors, preventative measures, means of early diagnosis, and treatment is critical. Despite ONJ occurring in the clinical setting of intravenous bisphosphonates, there are other causes associated with higher risk of ONJ, such as multiple dental extractions. Overall, it is important for imaging health care professionals to recognize, describe, and understand ONJ to help minimize biopsies and allow proper treatment to begin as soon as possible.

Impact of interfraction seroma collection on breast brachytherapy dosimetry - a mathematical model.

Purpose Balloon brachytherapy is a widely accepted modality for delivery of accelerated partial breast irradiation (APBI). Our hypothesis was that inter-fraction seroma collection around the balloon surface would have an adverse effect on dosimetry of the target. Material and methods This is a dosimetric re-planning study using two volumetric models (30 cc and 45 cc) in a Contura® multi-lumen balloon (MLB) catheter. In a previously treated patient, two customized baseline plans were generated using multiple channels of the Contura® catheter prescribed to the Planning Target Volume Evaluation (PTV_Eval). Symmetric expansions of 1.0 mm (0-9 mm) increments around the balloon surface were performed to simulate a “Virtual Seroma” (VS) accumulation for both balloon volumes and plans were obtained for each expansion using Eclipse Brachyvision™. An analysis of these plans was then performed to evaluate the effect of seroma accumulation on dosimetric parameters of V100 and V90. Results 20 plans were generated and analyzed (10 plans for each balloon volume), representing VS of 6.0-66.0 cc. There was a commensurate decrease in the dose delivered to the PTV_Eval V100 and V90 (as defined by the original treatment plan) with increasing VS accumulation leading to a sub-optimal coverage of the PTV_Eval. For 30 cc MLB catheter, V100 decreased by 1.4% and V90 decreased by 0.9% for every 1 cc of VS. For 45cc MLB catheter, V100 decreased by 1.3% and V90 decreased by 1.15% for every 1.0 cc accumulation of VS. Conclusions Balloon catheter-tissue adherence ensures daily dose delivery to the planned PTV_Eval. Accumulation of seroma, hematoma or air between HDR fractions can significantly impact PTV_Eval dosimetry. Vacuum-port aspiration prior to delivery of each fraction, if available, should be considered to minimize the risk of geographic under dosing.

Interfraction accumulation of seroma during accelerated partial breast irradiation: Preliminary results of a prospective study

PURPOSE To quantify and characterize the process of seroma accumulation during accelerated partial breast irradiation using multicatheter balloon brachytherapy. MATERIALS AND METHODS Twenty-two patients were treated using the Contura Multilumen brachytherapy catheter to a dose of 34Gy in 10 fractions over 5 treatment days. Serial aspirations of the vacuum port of the catheter were performed at the time of CT simulation and before each treatment. Volume and characteristics of fluid drawn were recorded. Univariate analysis was performed to evaluate various factors predictive of seroma formation. RESULTS Median patient age was 59.5 years, body mass index was 31, and volume of surgical specimen was 62.4cm(3). Median time from breast conservation surgery to placement of Contura catheter was 18.5 days. Pericatheter seroma, typically scant with a median volume of 0.75mL, was noted in 91% of patients at CT simulation. A total of 203 aspirations were performed with a median-aspirated seroma volume of 4.05mL. There was no significant correlation between the volume of seroma and histology (invasive vs. in situ), quadrant of location, body mass index, reexcision or reoperation, days from breast conservation surgery to balloon placement, or the volume of specimen removed. Radiation treatment factors, including balloon volume, balloon to skin distance, and planning target volume evaluation, also did not correlate with aspirated seroma. CONCLUSIONS Interfraction seroma accumulation has a variable pattern of development with no discernible predictors of occurrence. Routine pretreatment aspirations via vacuum port may potentially improve dosimetric reproducibility for a minority of patients.

Bisphosphonate-Related Osteonecrosis of the Jaw Mimicking Bone Metastasis

Osteonecrosis of the jaw is usually a potential complication of bisphosphonate therapy. In a cancer patient, this disease entity can be misdiagnosed as a metastatic lesion. Our aim is to make clinicians aware of bisphosphonate associated osteonecrosis of the jaw to prevent misdiagnosis and initiate proper treatment at the earliest. We present the case of a breast cancer patient with multiple bony metastases and a jaw lesion presumed to be metastases. After no response to palliative radiation, repeat radiological imaging studies revealed osteonecrosis of the jaw. Correlating a patients clinical information with findings on diagnostic imaging studies, such as SPECT bone and CT scans, can help identify this potential complication of bisphosphonate treatment. Early diagnosis helps minimize unnecessary biopsies and allows for the proper treatment to be instituted.