Dynamic CT angiography for cyberknife radiosurgery planning of intracranial arteriovenous malformations: a technical/feasibility report.

BACKGROUND: Successful radiosurgery for arteriovenous malformations (AVMs) requires accurate nidus delineation in the 3D treatment planning system (TPS). The catheter biplane digital subtraction angiogram (DSA) has traditionally been the gold standard for evaluation of the AVM nidus, but its 2D nature limits its value for contouring and it cannot be imported into the Cyberknife TPS. We describe a technique for acquisition and integration of 3D dynamic CT angiograms (dCTA) into the Cyberknife TPS for intracranial AVMs and review the feasibility of using this technique in the first patient cohort. PATIENTS AND METHODS: Dynamic continuous whole brain CT images were acquired in a Toshiba 320 volume CT scanner with data reconstruction every 0.5 sec. This multi-time-point acquisition enabled us to choose the CT data-set with the clearest nidus without significant enhancement of surrounding blood vessels. This was imported to the Cyberknife TPS and co-registered with planning CT and T2 MRI (2D DSA adjacent for reference). The feasibility of using dCTA was evaluated in the first thirteen patients with outcome evaluation from patient records. RESULTS: dCTA data was accurately co-registered in the Cyberknife TPS and appeared to assist in nidus contouring for all patients. Imaging modalities were complementary. 85% of patients had complete (6/13) or continuing partial nidus obliteration (5/13) at 37 months median follow-up. CONCLUSIONS: dCTA is a promising imaging technique that can be successfully imported into the Cyberknife TPS and appears to assist in radiosurgery nidus definition. Further study to validate its role is warranted.

Peptide receptor radionuclide therapy for aggressive atypical pituitary adenoma/carcinoma: variable clinical response in preliminary evaluation.

PURPOSE: There are limited treatment options for progressive atypical pituitary adenomas and carcinomas. Peptide receptor radionuclide therapy that targets somatostatin receptors has recently been proposed as a potential treatment option. The theoretical rationale for efficacy is elegant but evaluation of outcomes in the first patients treated for this indication is required to assess whether further study is warranted. METHODS: We performed a case review of the three pituitary patients we have treated with (177)Lutetium DOTATATE in our institution (two atypical adenomas, one carcinoma) and dosimetric analysis of the radiation uptake in one patient. RESULTS: Treatment was well tolerated. One patient with slowly progressive pituitary carcinoma has stable disease 40 months after completing the planned 4 cycles of treatment. Two patients with rapidly progressive atypical adenomas terminated treatment early due to continued disease progression. Dosimetric evaluation revealed inhomogenous uptake across the tumour (1.3-11.9 Gy with one cycle). CONCLUSION: We have found mixed results in our first 3 patients with stable disease achieved only in the patient with the more slowly progressive tumour. As only a limited number of centres offer Peptide receptor radionuclide therapy, a formal study with prospective data collection may be feasible and if carried out should include dosimetric evaluation of absorbed dose.

Utility of CT-cisternogram for radiosurgery in trigeminal neuralgia: A not-to-be forgotten technique.

Radiosurgery (RS) is a well-established ablative therapy for trigeminal neuralgia (TGN). Successful RS requires the delivery of an extremely high dose of radiation to a small cisternal portion of the nerve, which lies amidst critical structures. This study describes the utility of CT-cisternogram in RS targeting for TGN. We report on patients with TGN who required CT-cisternogram for target identification for CyberKnife (CK) RS at our institution between September 2010 and April 2015. CT-cisternogram is a well-tolerated procedure that adds useful information to RS planning. Illustrative cases with complex anatomy and MRI artifacts related to postoperative changes and Teflon implant are described. CT-cisternogram is a complementary imaging modality that is useful in some patients, for RS target delineation.

Durable control of locally recurrent renal cell carcinoma using stereotactic body radiotherapy.

Renal cell carcinoma (RCC) is generally poorly responsive to conventional radiation doses, and patients with inoperable local recurrence have limited therapeutic options. Stereotactic body radiotherapy (SBRT) is an increasingly available technology that allows delivery of a radiation schedule providing doses far more biologically effective against cancer cells than conventional radiotherapy. We present a case where durable disease control was achieved using SBRT in a patient with inoperable locally recurrent RCC who presented 18 years from original nephrectomy. The patient remains asymptomatic with no evidence of active disease 30 months following SBRT. This case highlights the need to reconsider the role of therapies with continuing advances in technology.

Proposal of a post-prostatectomy clinical target volume based on pre-operative MRI: volumetric and dosimetric comparison to the RTOG guidelines.

BACKGROUND: Recurrence rates following radiotherapy for prostate cancer in the post-operative adjuvant or salvage setting remain substantial. Previous work from our institution demonstrated that published prostate bed CTV guidelines frequently do not cover the pre-operative MRI defined prostate. Inadequate target delineation may contribute to the high recurrence rates, but increasing target volumes may increase dose to organs at risk. METHODS: We propose guidelines for delineating post-prostatectomy target volumes based upon an individual's co-registered pre-operative MRI. MRI-based CTVs and PTVs were compared to those created using the RTOG guidelines in 30 patients. Contours were analysed in terms of absolute volume, intersection volume (Jaccard Index) and the ability to meet the RADICALS and QUANTEC rectal and bladder constraints (tomotherapy IMRT plans with PTV coverage of V98% ≥98%). RESULTS: CTV MRI was a mean of 18.6% larger than CTV RTOG: CTV MRI mean 138 cc (range 72.3 - 222.2 cc), CTV RTOG mean 116.3 cc (range 62.1 - 176.6 cc), (p < 0.0001). The difference in mean PTV was only 4.6%: PTV MRI mean 386.9 cc (range 254.4 - 551.2), PTV RTOG mean 370 cc (range 232.3 - 501.6) (p = 0.05). The mean Jaccard Index representing intersection volume between CTVs was 0.72 and 0.84 for PTVs. Both criteria had a similar ability to meet rectal and bladder constraints. Rectal DVH: 77% of CTV RTOG cases passed all RADICALS criteria and 37% all QUANTEC criteria; versus 73% and 40% for CTV MRI (p = 1.0 for both). Bladder DVH; 47% of CTV RTOG cases passed all RADICALS criteria and 67% all QUANTEC criteria, versus 57% and 60% for CTV MRI (p = 0.61for RADICALS, p = 0.79 for QUANTEC). CTV MRI spares more of the lower anterior bladder wall than CTV RTOG but increases coverage of the superior lateral bladder walls. CONCLUSION: CTV contours based upon the patient's co-registered pre-operative MRI in the post-prostatectomy setting may improve coverage of the individual's prostate bed without substantially increasing the PTV size or dose to bladder/ rectum compared to RTOG CTV guidelines. Further evaluation of whether the use of pre-operative MRI improves local control rates is warranted.

Meningioma causing visual impairment: outcomes and toxicity after intensity modulated radiation therapy.

PURPOSE: To evaluate ophthalmologic outcomes and toxicity of intensity modulated radiation therapy (IMRT) in patients with meningiomas causing visual deficits. METHODS AND MATERIALS: A prospective observational study with formal ophthalmologic and clinical assessment of 30 consecutive cases of meningioma affecting vision treated with IMRT from 2007 to 2011. Prescriptions were 50.4 Gy to mean target dose in 28 daily fractions. The median follow-up time was 28 months. Twenty-six meningiomas affected the anterior visual pathway (including 3 optic nerve sheath meningiomas); 4 were posterior to the chiasm. RESULTS: Vision improved objectively in 12 patients (40%). Improvements were in visual field (5/16 patients), color vision (4/9 patients), acuity (1/15 patients), extraocular movements (3/11 patients), ptosis (1/5 patients), and proptosis (2/6 patients). No predictors of clinical response were found. Two patients had minor reductions in tumor dimensions on magnetic resonance imaging, 1 patient had radiological progression, and the other patients were stable. One patient experienced grade 2 keratitis, 1 patient had a minor visual field loss, and 5 patients had grade 1 dry eye. CONCLUSION: IMRT is an effective method for treating meningiomas causing ophthalmologic deficits, and toxicity is minimal. Thorough ophthalmologic assessment is important because clinical responses often occur in the absence of radiological change.

Multi-disciplinary management for patients with oligometastases to the brain: results of a 5 year cohort study.

BACKGROUND: The incidence of oligometastases to the brain in good performance status patients is increasing due to improvements in systemic therapy and MRI screening, but specific management pathways are often lacking. METHODS: We established a multi-disciplinary brain metastases clinic with specific referral guidelines and standard follow-up for good prognosis patients with the view that improving the process of care may improve outcomes. We evaluated patient demographic and outcome data for patients first seen between February 2007 and November 2011. RESULTS: The clinic was feasible to run and referrals were appropriate. 87% of patients referred received a localised therapy during their treatment course. 114 patients were seen and patient numbers increased during the 5 years that the clinic has been running as relationships between clinicians were developed. Median follow-up for those still alive was 23.1 months (6.1-79.1 months). Primary treatments were: surgery alone 52%, surgery plus whole brain radiotherapy (WBRT) 9%, radiosurgery 14%, WBRT alone 23%, supportive care 2%. 43% received subsequent treatment for brain metastases. 25%, 11% and 15% respectively developed local neurological progression only, new brain metastases only or both. Median overall survival following brain metastases diagnosis was 16.0 months (range 1-79.1 months). Breast (32%) and NSCLC (26%) were the most common primary tumours with median survivals of 26 and 16.9 months respectively (HR 0.6, p=0.07). Overall one year survival was 55% and two year survival 31.5%. 85 patients died of whom 37 (44%) had a neurological death. CONCLUSION: Careful patient selection and multi-disciplinary management identifies a subset of patients with oligometastatic brain disease who benefit from aggressive local treatment. A dedicated joint neurosurgical/ neuro-oncology clinic for such patients is feasible and effective. It also offers the opportunity to better define management strategies and further research in this field. Consideration should be given to defining specific management pathways for these patients within general oncology practice.