Transnasal and transsphenoidal MRI-guided biopsies of petroclival tumors

Stereotactic biopsy approach to the upper clivus through the middle fossa floor that avoids pneumatised cavities and the intradural compartment

BACKGROUND

Biopsies of clival lesions are usually performed, under general anaesthesia, through an anterior endoscopic approach or, alternatively, through a trans-nasal or trans-oral stereotactic approach.

METHODS

A 57-year-old man with a symptomatic osteolytical lesion of the clivus, who refused general anaesthesia, underwent a sterotactically guided biopsy of the lesion by an antero-lateral approach through the temporal and sphenoid bones.

RESULTS

Biopsy was successfully performed and the resulting diagnosis was myeloma. The patient was comfortable during and after surgery and there were no complications.

CONCLUSIONS

The present stereotactic antero-lateral approach to the biopsy of the upper clivus can be considered an useful adjunct to the current trans-oral and transnasal approaches that often require general anaesthesia.

MR-guided abdominal biopsy using a 1.5-Tesla closed system: a feasibility study

BACKGROUND

MR-guided biopsy may aid to obtain samples in cases which are not feasible with conventional US or CT guidance.

PURPOSE

To evaluate safety and efficacy of MRI-guided abdominal biopsy at 1.5-T closed MR system.

METHODS AND MATERIALS

MRI guided abdominal biopsy was performed using Siemens Avanto 1.5-T closed MR system. Eighteen samples were obtained in 10 patients under local anesthesia using a novel technique to define skin entry site. None of the cases included in the study were amenable to biopsy using the conventional ultrasound (US) or computed tomography (CT) guidance. MR compatible 18G needle (US Biopsy) was used to obtain biopsy samples. Intravenous gadolinium was used in two patients for better delineation during biopsy. Patients were followed up for 3-5 h and were discharged on the same day.

RESULTS

Technical success was achieved in all patients. Average number of biopsy passes were two (range 1-4). All biopsy samples were adequate for histopathological examination. Average size of the core biopsy specimen was 9 mm.

CONCLUSION

1.5-T closed MR system allows adequate biopsy sampling from various abdominal organs. This technique may help to sample lesions which are not otherwise amenable for biopsy under conventional CT or US guidance.

Interventional and intraoperative MRI at low field scanner--a review

Magnetic resonance imaging (MRI) is a cutting edge imaging modality in detecting diseases and pathologic tissue. The superior soft tissue contrast in MRI allows better definition of the pathology. MRI is increasingly used for guiding, monitoring and controlling percutaneous procedures and surgery. The rapid development of interventional techniques in radiology has led to integration of imaging with computers, new therapy devices and operating room like conditions. This has projected as faster and more accurate imaging and hence more demanding procedures have been applied to the repertoire of the interventional radiologist. In combining features of various other imaging modalities and adding some more into them, interventional MRI (IMRI) has potential to take further the interventional radiology techniques, minimally invasive therapies and surgery. The term "Interventional MRI" consists in short all those procedures, which are performed under MRI guidance. These procedures can be either percutaneous or open surgical of nature. One of the limiting factors in implementing MRI as guidance modality for interventional procedures has been the fact, that most widely used magnet design, a cylindrical magnet, is not ideal for guiding procedures as it does not allow direct access to the patient. Open, low field scanners usually operating around 0.2 T, offer this feature. Clumsy hardware, bad patient access, slow image update frequency and strong magnetic fields have been other limiting factors for interventional MRI. However, the advantages of MRI as an imaging modality have been so obvious that considerable development has taken place in the 20-year history of MRI. The image quality has become better, ever faster software, new innovative sequences, better MRI hardware and increased computing power have accelerated imaging speed and image quality to a totally new level. Perhaps the most important feature in the recent development has been the introduction of open configuration low field MRI devices in the early 1990s; this enabled direct patient access and utilization of the MRI as an interventional device. This article reviews the current status of interventional and intraoperative MRI with special emphasis in low field surrounding.

Percutaneous Biopsy from Blinded to MR Guided: An Update on Current Techniques and Applications

The advent of interventional MR imaging techniques as well as their adoption to guide percutaneous biopsies and aspirations has served as a further step along a series of technical refinements that commenced with the implementation of image-guided approaches for tissue sampling. Nowadays, the practice of and the expectations from these procedures are quite different from those of the blind percutaneous thrusts performed in the late nineteenth and early twentieth centuries. As the field of interventional MR imaging continues to flourish and to attract more radiologists who realize the many opportunities that this technology can offer to their patients, there is a need for a full comprehension of the concepts, techniques, limitations, and cost-effectiveness of MR imaging guidance to present this service to clinical partners in the appropriate setting. Radiologists should also recognize the need for their significant involvement in the technical aspects of MR-guided procedures, because several user-defined parameters and trajectory decisions can alter device visualization in the MR imaging environment and hence affect procedure safety.

Expanded endonasal approach: fully endoscopic, completely transnasal approach to the middle third of the clivus, petrous bone, middle cranial fossa, and infratemporal fossa

Object

The middle third of the clivus and the region around the petrous internal carotid artery (ICA) is a difficult area of the skull base in terms of access. This is a deep area rich with critical neurovascular structures, which is often host to typical skull base diseases. Expanded endoscopic endonasal approaches offer a potential option for accessing this difficult region. The objective of this paper was to establish the clinical feasibility of gaining access to the paraclival space in the region of the middle third of the clivus, to provide a practical modular and clinically applicable classification, and to describe the relevant critical surgical anatomy for each module.

Methods

The anatomical organization of the region around the petrous ICA, cavernous sinus, and middle clivus is presented, with approaches divided into zones. In an accompanying paper in this issue by Cavallo, et al., the anatomy of the pterygopalatine fossa is presented; this was observed through cadaveric dissection for which an expanded endonasal approach was used. In the current paper the authors translate the aforementioned anatomical study to provide a clinically applicable categorization of the endonasal approach to the region around the petrous ICA. A series of zones inferior and superior to the petrous ICA are described, with an illustrative case presented for each region.

Conclusions

The expanded endonasal approach is a feasible approach to the middle third of the clivus, petrous ICA, cavernous sinus, and medial infratemporal fossa in cases in which the lesion is located centrally, with neurovascular structures displaced laterally.

Interventional and intraoperative MR: review and update of techniques and clinical experience

The concept of interventional magnetic resonance imaging (MRI) is based on the integration of diagnostic and therapeutic procedures, favored by the combination of the excellent morphological and functional imaging characteristics of MRI. The spectrum of MRI-assisted interventions ranges from biopsies and intraoperative guidance to thermal ablation modalities and vascular interventions. The most relevant recently published experimental and clinical results are discussed. In the future, interventional MRI is expected to play an important role in interventional radiology, minimal invasive therapy and guidance of surgical procedures. However, the associated high costs require a careful evaluation of its potentials in order to ensure cost-effective medical care.

Klinischer Einsatz der interventionellen MRT (iMRT)

The integration of diagnostic and therapeutic procedures by MRI is based on the combination of excellent morphologic and functional imaging. The spectrum of MR-guided interventions includes biopsies, thermal ablation procedures, vascular applications, and intraoperative MRI. In all these applications, different scientific groups have obtained convincing results in basic developments as well as in clinical use. Interventional MRI (iMRI) is expected to attain an important role in interventional radiology, minimal invasive therapy, and monitoring of surgical procedures.