Silk Vista Baby for the Treatment of Complex Posterior Inferior Cerebellar Artery Aneurysms.

BACKGROUND: Treatment of small-caliber vessel lesions using flow diverters remains challenging because of vasculature's narrow luminal diameter and tortuosity. This in turn makes navigation and delivery of conventional devices with standard microcatheters more difficult. The Silk Vista Baby (SVB, Balt) flow diversion device was designed for ease of use in vessels with a smaller diameter, distal lesions, and 0.017 ″ microcatheter delivery systems. OBJECTIVE: To report the outcomes of the SVB device on the treatment of posterior inferior cerebellar artery (PICA) aneurysms. METHODS: Databases from different centers were retrospectively reviewed for PICA aneurysms treated with SVB. Demographic information, clinical presentation, radiographic characteristics, procedural complications, and immediate postprocedure outcomes were obtained. RESULTS: Fourteen patients harboring 15 true PICA aneurysms were treated between January 2019 and June 2021. Nine were female (n = 9/14; 64.2%), and the mean age was 51 ± 14.9 years. Most patients had previously ruptured aneurysms, treated by another endovascular technique. Six aneurysms were located distally (n = 6/15; 40%). The mean neck size was 3 mm (SD 1.35, range 2.5-5 mm), whereas the mean PICA diameter was 1.6 mm (SD 0.26, range 1.5-1.7 mm). The mean length of follow-up was 6 months (SD 8.28, range 4.5-16 months). Treatment-related adverse events included 1 case of transient hypoesthesia. Two additional events were reported, but adjudicated as unrelated to the procedure. Complete occlusion, measured as Raymond-Roy class I, was achieved in all cases. CONCLUSION: The SVB device was safely and effectively used in the treatment of PICA aneurysms. The smaller delivery system profile reduces the risk of procedure complications and creates new treatment options for distal lesions.

Patient-specific anatomical models for radioiodine dosimetry in treatment of hyperthyroidism: is it necessary?

PURPOSE: To investigate the necessity of patient-specific dosimetry calculations using individualized models for hyperthyroid patients treated with radioactive iodine (RAI). This treatment modality was considered to be safe and effective; however, a recent publication indicated associations between greater organ-absorbed doses of RAI and risk of cancer death. METHODS: Ten patient-specific models which ranged in size were used (from 152.5 to 184 cm in height and from 44 to 88 kg in mass). The time-integrated activity coefficients (TIAC) were evaluated from the 2017 Leggett's model assuming 24 h radioactive iodine uptakes (RAIU) of 30, 50, 70, and 90% and two intake routes for normal uptake (ingestion and injection). A set of 131 I S factors (mGy MBq-1  h-1 ) from the patient-specific phantoms including 12 source regions were provided in this study. These S factors were used together with the new TIACs to present dose coefficients. RESULTS: The MC-based patient-specific S factors were compared with the ICRP standard data and the variation ranges (%) of (-65, +210) and (-57, +193) were reported for self and cross S factors, respectively. However, for self S factors, those intervals were reduced to (-8.3, +4.6) when mass correction was applied. Moreover, variations on organ dose coefficients were evaluated and the thyroid contributions were also assessed for 24 h RAIU of 30, 50, 70, and 90%. Considering that the thyroid contribution to adjacent normal organs is high and the variations on cross dose coefficients are also considerable, variations (%) on normal organ doses were estimated to be up to (-63, +132), with a planned thyroid absorbed dose of 150 Gy. CONCLUSION: Given the large variations on organ doses, the standard data are not an appropriate substitute for patient-specific data. Particularly, when accurate patient-specific dose estimation is a serious concern in RAI treatment (RAIT) for nuclear medicine practitioners. However, acquiring computed tomography (CT) images for patient-specific modeling will impose additional radiation dose to patients. It was concluded that CT imaging limited to the region from skull base to mid thorax (i.e., for organs with RAIT doses of >~50 mGy with a dose of 150 Gy prescribed to the thyroid) may be suggested and is clinically relevant because the normal organ dose increments are not greater than 10%.