A. Krone

Correlation of Intra-Operative Ultrasound with Histopathologic Findings After Tumour Resection in Supratentorial Gliomas A Method to Improve Gross Total Tumour Resection

SummaryThe 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 (≤3 mm in diameter) rather regular hyperechoic rim surrounding the resection cavity.47 out of 53 biopsies taken from hyperechoic areas (group 1) (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 surgeons assessement 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 real-time sonography in the evaluation of intracranial neoplasms and arteriovenous malformations

Transcranial color-coded real-time sonography (TCCS) was performed in 57 patients with primary intracranial brain tumors (n = 49) or arteriovenous malformations (n = 8) to evaluate its diagnostic potential. In 46 patients (81%), lesions could be identified employing this technique. In 7 patients, transcranial ultrasound examination was not feasible because of bone thickness; in the remaining 4 patients, the tumor was indistinguishable from adjacent brain tissue despite sufficient insonation, suggesting that these neoplasms are isoechogenic. The sonographic features of brain tumors were very similar: a hyperechogenic matrix of the lesion was interspersed by hypoechogenic pixels. Larger hypoechogenic areas (0.5-1 cm) gave evidence of tumor necrosis. Differences between the findings of TCCS and computed tomography concerning tumor size were found in 7 patients, in whom TCCS revealed an area of smaller extension within the corresponding hypodense area on the computed tomographic scan. Perifocal brain edema could not be detected by ultrasound examination. In 13 patients, a thin, hypoechogenic peritumoral halo was disclosed that did not correlate with perifocal brain edema identified by computed tomography and that may have been due to compression of adjacent parenchyma. In patients with arteriovenous malformations, TCCS permitted the identification of the main feeders, the nidus, and the draining venous system by color-coded depiction of intravascular blood flow. In conclusion, TCCS is an additional method for initial diagnosis and highly suitable for follow-up in tumor patients and provides valuable information about tissue characteristics and blood flow.

Intra-operative colour-duplex-sonography in the surgical management of cerebral AV-malformations.

Summary In this prospective study the role of intra-operative Colour-Duplex-Sonography (=CDS) during surgery of arteriovenous malformations (=AVM) is evaluated. During the last three years 20 consecutive patients with supratentorial AVMs were examined by intra-operative CDS in order to evaluate the potential of CDS to 1) localize the AVM, 2) differentiate between embolized and perfused parts, 3) identify feeding and draining vessels and 4) control the complete excision of the AVM. All AVMs were localized supratentorially, 9 were grade I and II (according to Spetzler and Martin [31]), 8 grade III and 3 grade IV. 11 were partly embolized and 8 associated with an intracerebral bleeding. In all cases the nidus was correctly localized sonographically by its typical bidirectional flow pattern in Colour-mode. CDS guided the surgeon directly to all (11 cases) deep-seated AVMs (2 to 4cm subcortically). The smallest nidus measured 10 mm. 28 of 34 angiographically defined main feeding and 18 of 23 draining vessels were identified. 14 patients were controlled sonographically at the end of the resection regarding the completeness of excision. In 11 patients CDS was negative and was confirmed by either postoperative angiography or MRI in 10 patients. In one case residual AVM tissue was missed by CDS. Positve CDS findings in 3 cases were all confirmed by microscopic re-inspection, angiography and CCT. Our results suggest that CDS is able to localize AVMs intra-operatively with minimal instrumentation. It allows safe navigation to deep-seated malformations with high accuracy. Feeding and draining vessels can be identified and completeness of resection can be controlled.

Reliability of transcranial colour-coded real-time sonography in assessment of brain tumours: correlation of ultrasound, computed tomography and biopsy findings.

Transcranial colour-coded real-time sonography (TCCS) was carried out in 25 patients with brain tumours to determine whether this noninvasive method provides additional information about the extent of solid tumour, its differentiation from oedema, and its tissue components. All 25 patients had serial computed tomography (CT)-guided stereotactic biopsies. Comparison of ultrasound, CT and histological findings revealed that the vast majority of contrast enhancing areas on CT were hyperechogenic (32/33; 97%) and contained tumour tissue (29/32; 91%). Hyperechogenic areas always represented solid tumour (23/23 patients), even when CT showed low density non-enhancing lesions. In lestons hypoechogenic on TCCS and low density on CT, histology consistently revealed necrotic tumour (7/7). Biopsies obtained from parenchyma with normal echogenicity revealed tumour in only 3 of 16 speciemens. Despite the high specificity of TCCS in the differentiation of tumour components, its sensitivity to tumour was inferior to that of CT (24/25; 96%). TCCS thus allows noninvasive preoperative identification of tumour tissue and its extent setting.

Ultrasound-guided neuronavigation of deep-seated cavernous haemangiomas: clinical results and navigation techniques

The aim of this study was to evaluate guidance techniques and patient outcomes of ultrasound-guided neuronavigation of deep-seated intracerebral cavernous hemangiomas (CAs). Thirty-five patients with deep-seated intracerebral CAs with sizes ranging between 7 and 45 mm were operated upon only with ultrasound-guidance. Twenty-seven were located in or near eloquent regions. In 30 patients dissection to the lesion was performed through sulci and fissures. The best approach to a lesion based on surface anatomy and depth was determined using sonographic information. Navigation was done sonographically. In five patients the shortest approach via a corticotomy was determined sonographically. Twenty-six patients had no neurological deficit postoperatively. Preoperative deficits improved in seven of nine patients. Fifteen of 19 patients suffering epileptic seizures had no seizures postoperatively. Intraoperative sonography revealed residual CA tissue after microsurgical extirpation in two cases. This report shows that intraoperative sonographic navigation provides safe guidance to deep-seated CAs with good clinical outcome independent of size.

Nocardial cerebral abscess cured with imipenem/amikacin and enucleation

A 72 year old female with cerebral abscess due to Nocardia farcinica is reported. Needle aspiration, antimicrobial therapy using a new combination of imipenem and amikacin, and, finally, surgical excision led to prompt and complete recovery. This is the oldest patient to survive cerebral nocardiosis reported in the literature. This infection, is usually regarded as opportunistic and is encountered with increasing frequency in immunocompromised conditions (organ transplantation, chemotherapy, underlying disabling disorder, acquired immunodeficiency syndrome, etc.). The literature is extensively reviewed for various aspects of this disease including prognostic factors, recent developments in antibiotic therapy (imipenem, amikacin, minocycline etc.) and the essential role of surgery in the treatment strategy.

Localization and Characterization of Intracerebral Cavernous Angiomas by Intra-Operative High-Resolution Colour-Duplex-Sonography

Summary The aim of this prospective study was to evaluate the reliability of high-resolution Colour-Duplex-Sonography (= CDS) in intra-operative localization, guiding and characterization of intracerebral cavernous angiomas (= CA). During a time period from 5/93 to 12/96 a total of 26 patients with 21 supratentorial and 5 infratentorial CA (15 of them deep-seated) were examined intra-operatively by CDS. The study focussed on 1. sonographic characterization, 2. localization in relationship to anatomical landmarks, 3. navigation, 4. correlation of sonographic to magnetic resonance imaging (= MRI), intra-arterial angiography (= DSA) and histological results and 5. control of complete resection. All CA appeared sonographically as hyperechoic lesions without flow-signals in Colour-mode. Imaging of anatomical landmarks as cerebral sulci, brain stem, insular cistern, falx, ventricles and vessels could be used for precise localization and successful guiding to 15 deep-seated lesions. The correlation of the size between MRI and CDS was excellent (1.4 mm mean difference, range from 0 to 5 mm). All 4 associated venous anomalies, as verified by pre-operative DSA, could be visualized and identified by CDS. The completeness of exstirpation was controlled sonographically in 14 cases and confirmed by MRI (= 10) and CT (= 4). This study provides the first comprehensive intra-operative characterization of CAs by CDS and correlation to MRI and DSA. Furthermore it demonstrates the reliability of CDS for intra-operative localization and guiding as well as its potential to control the complete exstirpation.

New ultrasound techniques and their application in neurosurgical intra-operative sonography

Abstract We describe a variety of new ultrasound techniques by their physical background, potentials and applications regarding usefulness during intra-operative neurosurgical procedures. Transducers like highfrequency and small rotating probes fitting into neuroendoscopes, imaging techniques as extended field-ofview technique, harmonic imaging, echo-enhancers, 3-D imaging and the real-time integration of neurosonography with pre-operative CT- or MR-data are mentioned. The technical or physical principles are explained, followed by a discussion of these techniques from available literature dealing with their intra-operative neurosurgical applications and the experience of the authors with the techniques. With higher frequencies micromillimeter imaging is possible and small probe allows endoneurosonography. Echo-enhancers and harmonic imaging improve the signal-to-noise ratio and 3-D imaging and extended field-of-view techniques allows a better understanding of the pathoanatomy. With the real-time integration of intra-operative ultrasound images and pre-operative CT or MR images additional information, like hemodynamic pattern, are available for the neurosurgeon. Although until now only a limited number of reports about new sonographic techniques during intra-operative application in neurosurgery exist, the methods seem to be promising in creating images easier to understand, incorporating more information about pathoanatomy and supplying the neurosurgeon with information additional to that provided by CT and MRI. [Neurol Res 2001; 23: 697-705]

Postoperative neuroimaging of high-grade gliomas: comparison of transcranial sonography, magnetic resonance imaging, and computed tomography.

BACKGROUND A precise and comprehensive knowledge of tumor burden and its extent and growth pattern in the pre- and postsurgical states is required to optimize tumor therapy and to determine treatment success and failure. This prospective study compares the diagnostic potential of computed tomography (CT), magnetic resonance imaging (MRI), and transcranial sonography (TCS) in the postoperative follow-up of brain tumors. METHOD Twenty-six patients with high-grade gliomas were included in the study. After tumor debulking, a total of 31 biopsy specimens were obtained from the resection margin in 21 patients and histological findings were compared with the findings of early postoperative TCS, CT, and MRI. Findings indicating residual tumor tissue were nonlinear contrast enhancement at the resection site revealed by CT or MRI or hyperechogenic lesions revealed by TCS. Follow-up examinations using all three imaging techniques were performed every 3 months. The end points of the follow-up were tumor recurrence as defined by CT and MRI, death, or severe clinical deterioration. RESULTS On the basis of the above criteria, TCS identified residual tumor more often than did CT or MRI. In the group of 19 patients with histologically proven tumor remnants, residual tumor tissue was identified by TCS in all patients, whereas MRI and CT failed to show contrast enhancement in three and eight patients, respectively. However, the results of the TCS were false positive for one patient because of hemorrhage into the resection site. The average time to identification of tumor regrowth was 27 weeks using TCS, 29 weeks using CT, and 33 weeks using MRI. Only the differences between TCS and MRI reached statistical significance. For one patient, multicentric tumor recurrence was not detected using TCS. CONCLUSION TCS may complement CT and MRI in the postoperative follow-up of patients with high-grade gliomas. Because none of these modalities alone is both sensitive and specific, an integrated analysis of imaging findings is recommended.

Intraoperative color duplex sonography of basal arteries during aneurysm surgery.

This prospective study aimed at (1) characterizing the duplex sonographic appearance of cerebral aneurysms, (2) visualizing their location, and (3) ensuring the complete occlusion of the aneurysm as well as the patency of the basal arteries during aneurysm surgery. During 9 months 30 craniotomies for aneurysm clipping in 29 patients were monitored intraoperatively by Bmode and color–coded duplex sonography. Following craniotomy the aneurysm and the preaneurysmatic and postaneurysmatic arteries were sonographically visualized before and after clipping and removal of the spatulas. Twenty–seven (90%) of 30 aneurysms appeared as a hypoechoic structure. Together with the typical dichromatic picture in the color mode and the characteristic bidirectional flow pattern in the duplex mode, 29 (97%) of 30 aneurysms were identified and localized anatomically correctly. Eighty (99%) of 81 relevant vessels were visualized and measured with the Doppler mode. After clipping, flow was detectable in all major arteries except 3 middle cerebral artery (MCA) branches. In 1, occlusion was confirmed by postoperative angiography. In the other 2, early postoperative computed tomography showed an infarction of the corresponding MCA territories. This study demonstrated the potential of color duplex sonography to visualize and characterize cerebral aneurysms and adjacent basal arteries before and after clipping. It offers a noninvasive intraoperative method to control the patency of basal arteries and complete occlusion of the aneurysm.