Intraoperative ultrasound (iUS) allows the generation of real-time data sets during surgical interventions.
Although the quality of the gray-scale US image before tumor resection is excellent, little information is gained in terms of perfusion of the lesion, even with the aid of Doppler US and tumor margins are not always clearly detectable with B-mode ioUS only.
see 3D ultrasound
Brock et al., analyzed prospectively 49 patients with Chiari type 1 deformity, operated at the Hospital das Clinicas, College of Medicine, University of São Paulo. Patients underwent decompressive surgery with or without opening of the duramater after intraoperative ultrasonography measuring flow rate. A value of 3cm/s was considered a cut-off. Quality of life before and after surgery and the improvement of neck pain and headache were evaluated.
Among 49 patients enrolled, 36 patients (73%) had CSF flow above 3 cm/s and did not undergo duraplasty. In 13 (27%) patients with initial flow <3 cm/s, a dural opening was performed together with duraplasty. All patients improved comparing pre and post operative scores and all clinical parameters evaluated did not differ between both surgical groups. Patients submitted to bone decompression alone had fewer complication rate.
Intraoperative USG with measurement of CSF allows the proper selection of patients with CM that can have a less invasive surgery with bone decompression without duraplasty 2).
A retrospective review of the medical charts of all pediatric patients who underwent neurosurgical treatment of a tumor between August 2009 and July 2015 at Albany Medical Center. Included were patients who were aged ≤ 21 years, who underwent brain or spinal tumor resection, for whom IOUS was used during the tumor resection, and for whom postoperative MRI (with and without contrast) was performed within 1 week of surgery.
Sixty-two patients met inclusion criteria for the study (33 males, mean age 10.0 years). The IOUS results very significantly correlated with postoperative MRI results (φ = 0.726; p = 0.000000011; negative predictive value 86.3% [95% CI 73.7%-94.3%]). These results exemplify a 71% overall gross-total resection rate and 80% intended gross-total resection rate with the use of IOUS (i.e., excluding cases performed only for debulking purposes).
The use of IOUS may play an important role in achieving a greater extent of resection by providing real-time information on tumor volume and location in the setting of brain shift throughout the course of an operation. The authors support the use of IOUS in pediatric CNS tumor surgery to improve clinical outcomes at low cost with minimal additional operating-room time and no identified additional risk 3).
Thirty three patients with small subcortical lesions. The maximum diameter of the lesions ranged between 18 and 30 mm. The depth of the lesion was described as the distance between the cortical surface and most outer point of the lesion. The mean of the depth of the lesions was 10.56 mm ranging between 3.3 and 18.7 mm. Multiple skin staples were used as irremovable skin markers. Before and after dural incision, ultrasound was used to assess the lesion size and location, its relationship with the surrounding tissue and the Doppler function to reveal the blood supply to the lesion. In this study mean craniotomy diameter was 44 mm ranging between 32-55 mm. The location, extent, characteristics and adjacent tissue of the lesion were observed by high frequency ultrasonography during the operation. Kazanci et al. describe a simple, safe and effective method for determining a small skin incision and craniotomy combined with intraoperative ultrasound for small subcortical intracranial lesions for health center that does not have Intraoperative magnetic resonance imaging and navigation systems 4).
22 Patients harboring an intracerebral high-grade tumor were retrospectively included in this study (14 primary tumors, 8 metastasis). 14 of them had a perilesional edema equal or greater to lesion volume, 3 had previously received radiotherapy. Following macroscopic tumor debulking, the small (11 × 31 mm) L15 - 7io (Philips, Bothell, USA) high-frequency probe (7 - 15 MHz) was introduced into the resection cavity and its walls were meticulously scanned to search for tumor remnants. Postoperative MR scan was evaluated by a board-certified independent neuroradiologist, who assessed the EOR.
Gross total resection was achieved in 21 patients (95.5 %). One patient had a small tumor remnant (6 × 4 × 3 mm) of a very large (80 × 60 × 74 mm) anaplastic astrocytoma, detected in the postoperative MR scan. A permanent postoperative hemiparesis was diagnosed in one patient with a metastasis in the motor area, while the other patients recovered without permanent neurological deficits from the surgery.
The hfioUS probe allowed in this study a precise detection of the tumor and a detailed discrimination between normal, pathological and edematous tissue in all 22 cases 5).