2GiovaniA_IntraoperativeNeuronavigation


 

 

 

 

 
Romanian Neurosurgery (2015) XXIX 2: 141 - 149           141 

 

 

 

 

 

 

 

Intraoperative neuronavigation integrated high resolution 

3D ultrasound for brainshift and tumor resection control 

A. Giovani1, F. Brehar, Narcisa Bucur, D. Martin1, R.M. Gorgan 

1PhD Student, “Carol Davila” University of Medicine and Pharmacy, Bucharest 

“Bagdasar-Arseni” Emergency Clinical Hospital, Bucharest 

 
Abstract: INTRODUCTION: The link between the neurosurgeon’s knowledge and the 

scientific improvements made a dramatic change in the field expressed both in 

impressive drop in the mortality and morbidity rates that were operated in the beginning 

of the XXth century and in operating with high rates of success cases that were 

considered inoperable in the past. Neuronavigation systems have been used for many 

years on surgical orientation purposes especially for small, deep seated lesions where the 

use of neuronavigation is correlated with smaller corticotomies and with the extended 

use of transulcal approaches. The major problem of neuronavigation, the brainshift once 

the dura is opened can be solved either by integrated ultrasound or intraoperative MRI 

which is out of reach for many neurosurgical departments. METHOD: The procedure of 

neuronavigation and ultrasonic localization of the tumor is described starting with 

positioning the patient in the visual field of the neuronavigation integrated 3D 

ultrasonography system to the control of tumor resection by repeating the 

ultrasonographic scan in the end of the procedure. DISCUSSION: As demonstrated by 

many clinical trials on gliomas, the more tumor removed, the better long term control of 

tumor regrowth and the longer survival with a good quality of life. Of course, no matter 

how aggressive the surgery, no new deficits are acceptable in the modern era 

neurosurgery. There are many adjuvant methods for the neurosurgeon to achieve this 

maximal and safe tumor removal, including the 3T MRI combined with tractography 

and functional MRI, the intraoperative neuronavigation and neurophysiologic 

monitoring in both anesthetized and awake patients. The ultrasonography integrated in 

neuronavigaton comes as a welcomed addition to this adjuvants to help the surgeon 

achieve the set purpose. CONCLUSION: With the use of this real time imaging device, 

the common problem of brainshift encountered with the neuronavigation systems is 

covered and any eventual tumor residue can be spotted by ultrasonography and resected. 

Key words: high resolution 3D ultrasound, neuronavigation, glioma 

 

 



 

 

 

 

 
142          Giovani et al          Intraoperative neuronavigation 

 

 

 

 

 

 

 

Introduction 

Neurosurgery is a very fast changing field 

of medicine and keeping up to date with new 

technologies is a must. This link between the 

neurosurgeon’s knowledge and the scientific 

improvements made a dramatic change in the 

field expressed both in impressive drop in the 

mortality and morbidity rates that were 

operated in the beginning of the XXth century 

and in operating with high rates of success 

cases that were considered inoperable in the 

past.  

The neuronavigation systems are as useful 

for orienting in the operative field as is the 

operative microscope or endoscope for 

visualization and MRI is for locating the lesion 

and designing an operative strategy.  Yet many 

of the experts rely on their orientation based 

on anatomical knowledge limiting the use of 

neuronavigation for small, deep seated lesions 

(less than 3 cm). In this cases it has been 

demonstrated that the use of neuronavigation 

is correlated with smaller corticotomies and 

with the extended use of transulcal 

approaches.  

A study in 2000 [1]  presented for the first 

time the integration of neurosurgery into an 

ultrasound machine as a method to cope with 

normal anatomic changes during brain 

surgery , known as brainshift.  

Compared to other methods against 

brainshift like intraoperative MRI, 

interventional MRI the ultrasound even in 2D 

or 3D offers real time images is much easier to 

use and needs less investment both of the time 

of the procedure and in the set up for the MRI 

system and special operating rooms. [5, 6, 22] 

Compared to the MRI the ultrasound has a 

poor image quality and it is difficult to 

interpret, in part due to the fact that it is not 

regularly used in neurosurgery. 

The first neuronavigation integrated to a 

ultrasonography system was used since 

November 1997 at the University Hospital in 

Trondheim. [1] 

There are only a few studies to compare 

intraoperative MRI with neuronavigation 

integrated ultrasonography and they conclude 

that iMR is the most advanced and reliable 

intraoperative imaging modality but given to 

the limited applicability due to high costs and 

especially designed operating rooms 

intraoperative ultrasonography is an 

acceptable alternative. [8, 9, 17, 20] 

Method 

In order to use this combined system a fine 

slice MRI with fiducials applied on the scalp of 

the patient should be performed in the day 

before or the day of the surgery. We avoid 

performing this MRI scan more than 1 day 

before surgery as the marks on the scalp may 

vanish giving an unacceptable error for 

navigation. 

We will chose for navigation from the 

acquired images the larger image series, either 

T1 or T2, or we can choose both and switch 

between them when needed. 

While loading the data into the Sonowand 

system the patient’s head is fixed in a Mayfield 

head holder. A Mayfield Frame with 4 

reflecting spheres is fixed to the device and a 

nonsterile probe pointer with 4 reflecting 

spheres attached is used to register the points 

marked with fiducials on the scalp. Usually 



 

 

 

 

 
Romanian Neurosurgery (2015) XXIX 2: 141 - 149           143 

 

 

 

 

 

 

 

after the first 3 or 4 points are registered in the 

frameless navigation system the pointer in the 

surgeon’s hand appears on the screen.  

During this procedure the three cameras of 

the video acquisition system should be pointed 

towards the surgeon’s hand as to include both 

the Mayfield frame and the pointer device.  An 

error less than 2 mm is acceptable. Than the 

incision spot is drawn on the skin and the 

operative field is properly draped.  Before the 

craniectomy the sterile neuronavigation probe 

can be used again to avoid dural veins or dural 

lakes when performing the burr holes. Before 

and after the dural incision both the 

neuronavigation pointer and the ultrasound 

probe can be used to identify the best spot for 

cortical incision. This should take into account 

the shorter path to the middle of the lesion and 

the avoidance of the eloquent cortex.  

The position of the ultrasound plane is 

shown on the monitor as the ultrasound probe 

has attached 4 reflecting spheres to integrate it 

into the neuronavigation system. The system 

can build 3D ultrasound images based on a 

slow freehand movement of the probe over the 

cortex for 15-30 seconds. The ultrasound 

image can be superimposed on the MRI slices 

or can be seen in a separate screen. By rotating 

the neuronavigation or the ultrasound probe, 

different images are acquired the image shifts 

between the 3 planes (sagittal, coronal and 

horizontal). 

When the margin of the tumor facing the 

surgeon is reached the tip of the probe is used 

to mark it and after tumor removal the probe 

is inserted in the cavity to show the extent of 

removal. At this point when the resection is 

macroscopically total, the ultrasound is used 

again with continuous irrigation of the cavity 

to verify if there is any tumor remnant left.  

We have a limited experience with this 

device, only 7 patients, but it proved very 

useful in localizing and documenting the 

tumor resection. We used this device in cases 

of metastases, malignant or low grade gliomas 

or in cases of other intraparenchimal lesions 

like cavernomas especially when the lesion was 

located in or near the eloquent areas. 

Depending on the MRI sequence that is 

included in the study more information about 

the surroundings of the tissue can be gained. 

For some cases where we found important 

vessels in close contact with the tumor we used 

an angio MRI sequence superimposed on the 

regular T1 image that we used for navigation. 

This proved very useful especially when 

performing the ultrasonography 3D 

acquisition.  

Discussion 

Since the first experiments with ultrasound 

on human brain in 1950, 20 years passed for 

the real time 2D imaging to be introduced into 

clinical trials and 10 more years till this 

technology became available on the market. 

Nowadays most of the neurosurgical 

departments in high volume centers around 

the world have access to this technology. [11, 

15, 20] Its use is both in localizing the lesions, 

especially when these are small and located in 

eloquent cortex and in assessing the degree of 

tumor removal. In this era of evidence based 

medicine along with the microscope this 

device stands as a proof of the quality of 

surgery. [17, 21, 23]   

As demonstrated by many clinical trials on 



 

 

 

 

 
144          Giovani et al          Intraoperative neuronavigation 

 

 

 

 

 

 

 

gliomas, the more tumor removed, the better 

long term control of tumor regrowth and the 

longer survival with a good quality of life. Of 

course, no matter how aggressive the surgery, 

no new deficits are acceptable in the modern 

era neurosurgery.[16,18,19] There are many 

adjuvant methods for the neurosurgeon to 

achieve this maximal and safe tumor removal, 

including the 3T MRI combined with 

tractography and functional MRI, the 

intraoperative neuronavigation and 

neurophysiologic monitoring in both 

anesthetized and awake patients. The 

ultrasonography integrated in neuronavigaton 

comes as a welcomed addition to this 

adjuvants to help the surgeon achieve the set 

purpose. [4, 7f] 

Some authors used all these methods 

combined in a series of patients both with high 

grade and low grade gliomas reporting an 

increased rate of tumor resection compared to 

the cases without the use of this techniques, yet 

further long time studies on the recurrence of 

the tumors are needed to prove the benefit of 

using this advanced technologies for the life 

and the survival of the patients.  [10, 12, 14] 

 

 

 

 

Conclusion 

The ultrasound integrated neuro-

navigation system is an invaluable tool, cost 

benefit acceptable, compared to other 

methods, for the intraoperative detection and 

removal of tumor remnants, after achieving 

macroscopic gross total resection.  With the 

use of this real time imaging device, the 

common problem of brainshift encountered 

with the neuronavigation systems is covered. 
 

 
Figure 1 - neuronavigation integrated 

ultrasonography system: the 3 video cameras are 

visible on an articulated arm above the touch screen 

monitor 

 



 

 

 

 

 
Romanian Neurosurgery (2015) XXIX 2: 141 - 149           145 

 

 

 

 

 

 

 

 
Figure 2 - in this case of parietal glioblatoma, the 52 yo woman presented for headache and left sided motor 

seizures; after performing the craniotomy the ultrasound probe scans the dura for the 3D image acquisition to be 

superimposed on the neuronavigation MRI images. In this case we used both T1 and angio MRI images and the 

relation of the tumor with the vessels om its surface is shown (orange) 

 

 
Figure 3 - the same case during tumor removal when macroscopic total resection was achieved. The green line is 

the neuronavigation probe touching the margins of the resection cavity. The tip of the instrument stops before 

reaching the deep margin of the tumor, indirect sign that there is some tumor residue 



 

 

 

 

 
146          Giovani et al          Intraoperative neuronavigation 

 

 

 

 

 

 

 

 

 
Figure 4 - the same case after tumor removal, on the central ultrasound image the resection cavity can be 

observed: under continuous irrigation with serum after H2O2 has been applied in the cavity to obtain hemostasis, 

oxygen bubbles can be seen inside the resection cavity. Superimposing this set of images on the first set of images 

gives information about the degree of tumor resection 

 

 
Figure 5 - the same case in the end of the surgery when the rest of the tumor was removed and the tip of the 

probe is reaching the distal margin of the tumor. This check should be done for all the walls of the tumor 



 

 

 

 

 
Romanian Neurosurgery (2015) XXIX 2: 141 - 149           147 

 

 

 

 

 

 

 

 

 
Figure 6 - Comparing the 3D acquisition data before (left) and after (right) the tumor resection showing a 4.8 

mm brainshift. In order to limit the brain shift the head must be kept in a neutral position and the operating field 

should be continuously irrigated 

 

 
Figure 7 - navigating on a T2 MRI sequence in this case of lung cancer metastasis in a 62 yo heavy smoker man.  

After the tumor removal the pointer touches the deep margin of the tumor 

 



 

 

 

 

 
148          Giovani et al          Intraoperative neuronavigation 

 

 

 

 

 

 

 

 
Figure 8 - oxygen bubbles on ultrasound filling the resection cavity of a pseudocystic hypocampal glioma in a 30 

yo woman presenting with mesial temporal lobe epilepsy (MTLE) for generalized seizures and temporal seizures 

with euphoric and aggressive behavior 

 

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