The localization of brain tumors by ultrasonic techniques. A clinical review of 111 cases

Pediatric neuroimaging in pre-CT era: back to the future

Over the last half a century, diagnostic neuroimaging has made tremendous strides following the introduction of computerized tomography (CT) and subsequent magnetic resonance imaging (MR). Prior to that time, the neurological diagnosis was conducted with careful history taking, physical examinations, and invasive testing such as cerebral angiography, encephalography, and myelography. Techniques and contrast media for these tests have been refined and progressed over time. However, these invasive tests have diminished and are rarely used for daily practice in pediatric neurosurgery since the introduction of CT and MR. Nuclear brain scan and ultrasonography are non-invasive. A nuclear brain scan using radioactive tracers was used to demonstrate the laterality of the lesion without an intact blood-brain barrier, but was rarely performed after the CT era. On the other hand, improved ultrasonography made strides because of its portability and the lack of radiation exposure and sedation. It is often a first-line investigatory tool for neonatal evaluation. This article describes a review of developments and progresses of pediatric neuroimaging in the pre-CT era.

Ecografía en cirugía general

La ecografía es un estudio de imágenes diagnósticas con una amplia historia de uso en todas las especialidades de la Medicina; su advenimiento ha ayudado al enfoque diagnóstico e, incluso, al abordaje terapéutico de los pacientes. Desde su origen en el siglo XIX con mediciones de la velocidad del sonido en el agua, hasta el desarrollo de las máquinas de ultrasonografía sustentadas en los avances de la tecnología, la física y la ingeniería, se ha utilizado de manera notable en la Medicina. No hay duda de que, en el campo de la Cirugía General, ha sido útil para el manejo de los pacientes con enfermedad abdominal. La tecnología ecográfica permite identificar las características de un órgano normal y, cuando este patrón se afecta, orienta sobre la causa o determina la enfermedad que puede estar produciendo la alteración. En la presente revisión, se hace un recuento histórico del nacimiento de la ecografía, su aplicación en el campo de la medicina y su utilidad para el cirujano general en diversas circunstancias de la práctica quirúrgica.

The benefits of navigated intraoperative ultrasonography during resection of fourth ventricular tumors in children

BACKGROUND

Safe and radical excision of pediatric fourth ventricular tumors is by far the best line of management. Pediatric fourth ventricular tumor surgery is a challenge for neurosurgeons. The aim of the study is to present the authors' experience and to evaluate the possible benefits of neuro-navigated intraoperative ultrasonography (NIOUS) during the surgery of fourth ventricular tumors in children.

METHODS

Nonrandomized clinical trial study was conducted on 60 children with fourth ventricular tumors who were treated at Children's Cancer Hospital-Egypt. Mean age was 5.2 (±2.6) years. Thirty cases were operated upon utilizing the conventional microneurosurgical techniques. Another 30 cases were operated upon utilizing the NIOUS technique.

RESULTS

Total tumor excision was achieved in 29 cases (96.7%) of NIOUS group versus 24 cases (80%) in the conventional group. Mean operative time NIOUS group was 150 min [standard deviation (SD) = 18.28) versus 140.6 min (SD = 18.6) in the conventional group (p value = 0.055). The mean operative blood loss was 67.5 ml (SD = 17) in NIOUS group versus 71 ml (SD = 15.4) in the conventional group. Postoperative cerebellar mutism occurred in one case (3.3%) of NIOUS group versus in six cases (20%) of the conventional group.

CONCLUSIONS

Integration of navigated intraoperative ultrasonography in surgery of pediatric fourth ventricular tumors is a useful technology. It safely monitors maximum stepwise tumor excision. It is associated with less operative morbidity without significantly added operative time. It is a real-time, cost-effective, easily applicable, and easily interpretable tool that could substitute the use of intraoperative MRI especially in pediatric neurosurgery.

Intraoperative Ultrasonography of the Brain and Spine

Intraoperative ultrasonography can play a particularly useful role in facilitating surgery or guiding biopsies in the brain and spinal canal. Given the limited access that is frequently afforded to the operating surgeon, coupled with lesions that may be located in deep or seemingly inaccessible locations, sonography performed through tiny burr holes is useful for confirming location of lesions, guiding biopsy, and confirming extent of resection. In the spine, sonography is most helpful for confirming the precise location of intradural or extradural masses and guiding biopsies. In this review, we describe the technical requirements necessary for scanning the brain and spinal cord and suggest scanning techniques. The spectrum of pathological entities are illustrated along with potential pitfalls that the inexperienced operator is likely to encounter.

Transcranial colour-coded sonography for the bedside evaluation of mass effect after stroke

Repeated cranial computerized tomography scan examination in patients with elevated intracranial pressure is time consuming and requires patient transportation. We prospectively evaluated the diagnostic value of transcranial duplex sonography as a bedside tool for detection of the mass effect after space-occupying ischemic stroke and brain haemorrhage and for evaluating the width and dislocation of the ventricular system and the dislocation of brain mid-line structures. We used transcranial duplex sonography in 21 consecutive patients with space-occupying ischemic middle cerebral artery infarction and brain haemorrhage. The transcranial duplex sonography examinations were performed within 2 h before or after corresponding follow-up cranial computerized tomography scans. We measured the third ventricular width as a parameter for infratentorial and the mid-line shift for supratentorial space-occupying effect. In all patients, mid-line structures could be identified by transcranial duplex sonography. Significant third ventricular dilation was found subsequently in most patients with infratentorial mass effect, and mid-line shift occurred in all patients with supratentorial space-occupying lesions, respectively. The mean difference (absolute values) between transcranial duplex sonography and cranial computerized tomography measurements was 0.8 mm for the ventricular width (standard deviation 1 mm) and 1.1 mm for the mid-line shift (standard deviation: 1.46 mm), with a tendency for these parameters to be underestimated at higher values using transcranial duplex sonography. The linear correlation coefficients were R = 0.97 and R = 0.94, respectively. Transcranial duplex sonography appears to be a sufficiently reliable bedside method for evaluating the width and the lateral displacement of the third ventricle, as validated by cranial computerized tomography scan. Thus, it may be suitable for monitoring the space-occupying effect of both supra- and infratentorial strokes during treatment on critical care and stroke units.

Transcranial-transdural real-time ultrasonography during transsphenoidal resection of a large pituitary tumor. Case report

Ultrasonography has been used in neurosurgical operative procedures for several decades. The authors report the case of a large pituitary tumor that was subtotally resected using endoscopy via the transnasal-transsphenoidal approach, with the aid of transcranial real-time ultrasound. To our knowledge, this is the first reported case in which intraoperative transcranial-transdural real-time ultrasound was used to facilitate the resection of a skull base tumor.

Dislocation of the third ventricle due to space-occupying stroke evaluated by transcranial duplex sonography

Transcranial color-coded duplex sonography is a recently introduced method for visualizing (1) the blood flow velocity of the basal cerebral arteries and (2) the brain parenchyma as an acoustic impedance image. Dislocation of the third ventricle due to space-occupying stroke is an important clinical marker. This study evaluated the dislocation of the third ventricle from the brain midline by transcranial duplex sonography in 10 healthy volunteers. The mean dislocation was 0.2 +/- 0.3 mm. Eighteen stroke patients were investigated within 12 hours by both duplex sonography and computed tomography (CT) and the dislocation of the third ventricle was measured. Correlation between the two methods was high (r = 0.87, N = 27). Twelve stroke patients divided into three subgroups according to the extent of the space-occupying effects of the lesion were followed for 3 weeks. The increase and decrease of the dislocation of the third ventricle over the time were monitored. In conclusion, transcranial duplex sonography is a reliable tool to monitor dislocation of the third ventricle due to space-occupying stroke.

Operative ultrasound in general surgery

BACKGROUND

Since the introduction of real-time B-mode ultrasound during surgery almost 20 years ago, the use of operative ultrasound (OUS) has gradually expanded to a variety of surgical fields.

METHODS

A review of the history, technology, and specific applications of OUS in general surgery is presented with our clinical results of over 2300 operations.

RESULTS

The benefits provided by OUS are the acquisition of new information not otherwise available, complement to or replacement for operative radiography, confirmation of satisfactory completion of an operation, and guidance of surgical procedures. OUS possesses many advantages as an intraoperative tool, including safety, speed, unique imaging information, wide applicability, high accuracy and procedure guidance capability.

CONCLUSION

OUS is gaining wider acceptance in hepatobiliary, pancreatic, endocrine, and vascular surgery. Newer OUS modalities-color Doppler imaging and laparoscopic ultrasound-potentially may widen the applications of OUS in general surgery.

Correlation of intra-operative ultrasound with histopathologic findings after tumour resection in supratentorial gliomas. A method to improve gross total tumour resection

The aim of this study was to evaluate whether intra-operative ultrasound (= IOUS) is a suitable tool to detect residual tumour tissue after gross total resection in supratentorial gliomas. During a period of 18 months 45 patients with supratentorial gliomas (38 high-grade and 9 low-grade, according to the WHO-grading system [42]) were operated on. A series of 78 biopsies was taken from the resection cavity under continuous sonographic control at the end of surgery. Gross total tumour resection was intended in 34 patients (= 76%). The biopsy specimens were matched with the sonographic features at each biopsy site. The sonographic appearance of the resection margins were classified into 2 groups: (1) Irregular hyperechoic areas extending from the cavity into the iso-echogenic brain tissue and (2) a dense small (< or = 3 mm in diameter) rather regular hyperechoic rim surrounding the resection cavity. 47 out of 53 biopsies taken from hyperechoic areas (group I) (36 high-grade/11 low-grade) revealed solid tumour tissue (= 89%). 34 (= 72%) of these 47 areas were microscopically assessed as inconspicuous by the surgeon. 6 samples (4 high-grade/2 low-grade) contained tumour infiltration zone. 25 biopsies (23 high-grade/2 low-grade) taken from the hyperechoic rim [group 2] were diagnosed as follows: Normal brain tissue in 11, tumour infiltration zone in 8 and solid tumour tissue in 6 cases. Of 34 cases with "gross total removal" according to the surgeon's assessment 25 showed sonographic signs of residual tumour tissue, which was confirmed histologically as solid tumour tissue in 22 of these cases. It is concluded, that IOUS following resection of supratentorial gliomas can detect residual tumour tissue with high specificity and thus improve gross total resection. However, a thin hyperechoic rim surrounding the resection cavity (less than 3 mm in diameter) is a non-specific finding, which can mask thin residual tumour layers and therefore needs further evaluation of its nature.

Transcranial color-coded duplex sonography, magnetic resonance angiography, and computed tomography angiography: methods, applications, advantages, and limitations

Transcranial color-coded duplex sonography (TCCD), magnetic resonance angiography (MRA), and computed tomography angiography (CTA) are novel noninvasive or minimally invasive techniques for the study of the intracranial circulation. TCCD is relatively inexpensive and permits bedside examination. It improves the accuracy and reliability of conventional transcranial Doppler studies. The main limitation of TCCD are the ultrasonic windows. They restrict the area of insonation to the major cerebral arteries and the proximal part of its branches, lower the spatial resolution, and may prevent transtemporal insonation. Using MRA, both large and small intracranial arteries and veins can be imaged by selecting the appropriate imaging parameters. MRA provides morphologic information about the cerebral vessels, relying on blood flow as the physical basis for generating contrast between stationary tissues and moving spins. MRA is highly sensitive for the detection of occlusive disease in large intracranial arteries. However, with bright blood techniques the degree of stenosis tends to be exaggerated. Flow direction, eg, in collaterals, can be determined by selective or phase-contrast MRA. Perfusion imaging techniques provide information about blood flow at the capillary level. Diffusion imaging depicts molecular motion. TCCD and MRA used in combination or alone may eliminate the need for intra-arterial digital subtraction angiography (DSA) in most patients studied for occlusive cerebrovascular disease. DSA may be reserved for those patients where there is disagreement among the noninvasive techniques, and for the diagnosis of cerebral aneurysms and arteriovenous malformations. CTA relies on spiral CT technology and intravenous contrast injection. To date, intracranial use has been predominantly for the diagnosis of aneurysms. The role of CTA for the detection of nonaneurysmal intracranial vascular disease has yet to be established.

Transcranial color-coded duplex sonography of intracerebral hematomas in adults

BACKGROUND AND PURPOSE

It is well established from pediatric experience and animal experiments that intracerebral blood can be demonstrated by B-mode real-time duplex scanning. This has recently become feasible in adults as well. The present study investigated the changes in the sonographic appearance of intracerebral hematomas over the course of time.

METHODS

Starting in May 1991, 23 consecutive patients with intracerebral hematoma confirmed by computed tomography (21 spontaneous and 2 traumatic hematomas) were investigated within 1 year. They were monitored by repeated ultrasound scanning via the transtemporal approach. The sonographic appearance of the hematomas on B-mode scans and the angle-corrected blood flow velocity in the basal cerebral arteries were assessed.

RESULTS

There was unequivocal localization of the hematoma in 18 patients (78%). In 3 cases (13%), an adequate acoustic window could not be found. One small intracerebral hemorrhage was overlooked, and one extensive hemorrhage in the basal ganglia was misdiagnosed as a lobar hematoma. There was an alteration of the appearance of the hematoma with time. This was divided into three sonographic stages (initial stage, days 1 to 5; intermediate stage, days 6 to 10; and capsular stage, from day 10). In 14 of the 20 patients with an appropriate acoustic bony echo window, the blood flow velocity in the middle cerebral artery could be measured; in 1 of these patients, the signs of increasing intracranial pressure were apparent from Doppler frequency spectrum. In 5 patients, the intracerebral hematoma could be imaged but not the ipsilateral middle cerebral artery. One female patient showed cerebral circulatory arrest at the time of examination, which took place within 24 hours after the onset of clinical symptoms.

CONCLUSIONS

Most intracerebral hematomas in adults can be imaged in B-mode. Their sonographic appearance changes over the course of the disease. The advantages of this noninvasive method are its easy bedside operation and its suitability for follow-up; it is also less stressful than other imaging procedures. It yields a combination of structural and functional diagnostic information. In approximately 13% of the cases, the investigation was not feasible because of inadequate ultrasonic penetration of the intact skull.

Preliminary experience with the Berger neurobiopsy device for ultrasound guided aspiration and biopsy of intracranial lesions

Our preliminary experience is presented in the use of the Berger neurobiopsy device for ultrasound localization and biopsy of intracranial lesions through a burr hole. The apparatus and technique are described, along with the results of its use in the first 49 patients. In these patients 43 tumours were biopsied, all except one successfully. Three abscesses were aspirated, two intraventricular shunt catheters were sited and in one patient the diagnosis of postradiation gliosis was confirmed and tumour excluded. The advantages and limitations of the technique are discussed. It is advocated as a simple and time-saving alternative to CT stereotactic biopsy in many cases.

Correlation of neuropathologic findings, computerized tomographic and high-resolution ultrasound scans of canine avian sarcoma virus-induced brain tumors

The location, size, geometry and neuropathological findings of anaplastic astrocytomas (AA), gliosarcomas and sarcomas induced by the avian sarcoma virus (ASV) in dogs were compared with images generated using computerized tomography (CT) and real time high-resolution ultrasound (HRUS). Seven AA showed a wide range of findings on CT. Pre-contrast CT scans showed that the tumors could be hyper, hypo, or isodense. Three of seven AA had no contrast enhancement; two of these tumors were also isodense which resulted in a false-negative CT exam. Partial enhancement was seen in one tumor. This resulted in a sensitivity of detection of 72%. Real time HRUS was able to define tumor location, size and geometry of the AA missed or incompletely imaged by CT. All tumors were hyperechoic. Inhomogeneity of the echo pattern was due to hemorrhage, cyst formation, and necrosis within the tumors. Such secondary tumor characteristics were more accurately defined by HRUS compared to CT. Vasogenic edema in the brain surrounding tumors was of low density on CT and hypoechoic or indistinguishable from normal brain on US. Similar findings were seen in six gliosarcomas, two of which were not visualized by either pre- or post-contrast enhanced CT scans (sensitivity of 66%). Sarcomas differed in that they were either hyper or isodense; none were hypodense. The area of increased density matched the tumor geometry and correlated with dense cellularity and reticulin deposition. All 13 sarcomas showed contrast enhancement (100% sensitivity), but in two tumors, contrast enhanced CT underestimated the size of the tumor. Because of the large size and multiplicity of the sarcomas, HRUS imaging was not able to resolve the entire tumor volume because of limited imaging access. Intravenously injected horseradish peroxidase (HRP) crossed the tumor blood-brain barrier (BBB) only in those tumors in which contrast enhancement was seen. These studies suggest that intraoperative HRUS imaging may be useful in detecting and delineating human AA incompletely visualized by CT.

Intraoperative cranial sonography

The use of real time ultrasound in the neurosurgical operating room can enhance the ability to localize intracerebral masses, allow accurate needle biopsies, diminish the amount of potential damage to normal brain tissue, show the results of tumor resection, and help in the placement of ventricular and cyst shunts. The end result makes the surgical procedure faster, safer, and more accurate.

Tumors and cysts

"Congenital" tumors that cause hydrocephalus early in life are large masses and can easily be detected by ultrasound. CT is better for differentiating among the diverse types of mass lesions and is performed after screening by ultrasound. In our experience, ultrasound has proved successful for visualizing all of the intracranial cysts except those in the temporal fossa. Most patients with temporal fossa cysts, however, have other symptoms and signs, such as asymmetric head and seizures that lead to further investigation and correct diagnosis despite the failure to identify the temporal cysts by ultrasound. With newer and better ultrasound equipment, the detection of temporal fossa arachnoid cysts will be improved. We believe that neurosonography should be the initial tool for investigating infants and neonates who present with large heads or abnormally rapid increase in head size.

Ultrasonic diagnosis and follow-up of malignant brain tumors in childhood. A report of 4 cases and a review of the literature

Four patients between the ages of 2 and 20 years with malignant brain tumors were given several sonographic examinations, using an operative calvarial defect or sutural diastasis as an acoustic window. Three of our cases and 86% of cases with malignant brain tumors reported in the literature are echogenic, making possible primary sonographic diagnosis of tumor recurrence and echographic monitoring of tumor therapy.

Intraoperative Doppler and real time sonography in neurosurgery

Ultrasound Doppler sonography with miniaturized probes and high resolution offers new possibilities of intraoperative control of neurovascular procedures. Patency, flow direction stenoses and changes in resistance can be investigated atraumatically, repeatedly and without additional preparation. In bypass and aneurysm surgery, about 10% of the cases were shown by Doppler examinations to be unsatisfactory, with stenoses and occlusions. These could be immediately corrected without loss of time. In normal cases, the information on the local haemodynamics enlarges the knowledge as to the effects of the operation and make it safer. Real time ultrasonography, which can be easily adapted to neurosurgery, is a new atraumatic tool for localizing, in two dimensions, subcortical intrinsic processes, haematomas, ventricles ect. It is useful for guided biopsies and punctures and for the centering of the dura and brain incision over the middle of the lesion, especially in microsurgical procedures.

Intraoperative use of real-time ultrasonography in neurosurgery

The authors' experience with the intraoperative use of real-time ultrasonography during 21 neurosurgical procedures is reported. These procedures include neoplasm surgery in 18 cases, treatment of an arteriovenous malformation in one case, and ventricular catheter placement for hydrocephalus in two cases. In each of the neoplasm cases, the tumors were imaged just as well through the intact dura as on the brain surface itself. There were no cases in which the pathology could not easily be identified. The use of portable intraoperative ultrasonography in sterile coverings has proven to be extremely useful in localizing small subcortical neoplasms, as well as locating the solid and cystic portions of deep lesions. It has assisted in guiding needles for both biopsy and aspiration. It has also accurately identified and guided Silastic catheters during their placement in the ventricular system in cases of hydrocephalus. The authors have found real-time ultrasonography to be an important new tool in the operating room and will continue to rely on its imaging ability during selected procedures in the future.

Ultrasound directed placement of needles into brains of rhesus monkeys

Gray scale ultrasound identified the lateral and third ventricles, basal ganglia, columns of the fornix, and the suprasellar optic system of monkeys with craniotomy defects. Needles were placed in these structures under ultrasound guidance. Radiographs and formalin fixed brain sections confirmed the expected position of the needle tracts.

Experimental intraoperative localization of retained intracerebral bone fragments using transdural ultrasound

Precise intraoperative localization of retained bone fragments and foreign bodies avoids extensive brain disseciton, cerebral edema, damage to vital structures, incomplete debridement, and prolonged surgical procedures. Such localization after head trauma is often hampered by cerebral distortion, previous incomplete debridement, fragment migration, and surgical draping. Our intraoperative technique of transdural A-scanning using aspiration-biopsy transducers precisely localized 3.5-mm fragments without damage to underlying cortical tissue and vessles. Transdural A-mode echoencephalography was found to be more reliable for intracerebral depth estimations but epidural B-mode sonography was more useful for determining the size of fragments. Transdural ultrasound offered an intraoperative alternative to stereotaxic localization of retained bone fragments in experimental head trauma.