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Saturday, October 27, 2007

winamri.com Win a free MRI machine




One day after announcing a new cost-effective 1.5 T Magnetom Essenza MRI, Siemens has initiated a clever marketing strategy to bring attention to its product.
One small hospital in the US, currently without an MRI, has a chance to win the system by producing a short video on why they want the scanner, and entering it in the contest held over at WinAnMRI.com. The video with the most votes wins. So, whether you want to watch a bunch of amusing videos, or you want to side with your local hospital, head on to the website and vote.
(hat tip: WSJ Health Blog)





More about this MRI: ESSENZA 1.5 Tesla
Magnetom Essenza is a powerful and low-cost system that supports the clinical and financial success of its users. In addition to the low initial investment, savings of up to 25% can also be attained on installation costs for space, power requirements and construction. In part this is due to the light-weight 3.5 ton magnet, which even makes it possible to install the Magnetom Essenza on higher floors. If the system is replacing an existing MR system, it can reduce energy consumption up to 50% thanks to its high-performance electronics. Since the state-of-the-art magnet has zero helium boil-off, there is no need to regularly refill this expensive substance, and the system is always ready for operation.
Thanks to its powerful gradients (30mT/m), the new member of the Magnetom family delivers superior image quality for all clinical applications. Using Tim technology with Magnetom Essenza, the area of the patient to be examined can be covered with up to 25 seamlessly integrated coil elements that are read by 8 independent radiofrequency channels. Tim allows for flexibly combining up to four different coils, which make patient and coil repositioning virtually unnecessary. Tim also enables Parallel Imaging for reduced acquisition times. All of these benefits translate into workflow improvements as well as increased patient throughput, not to mention improving the profit situation. As an example, a complete examination of the entire central nervous system can be performed in less than ten minutes.
Another powerful new innovation is the IsoCenter Matrix coil. It is permanently positioned at the isocenter of the magnet and therefore always in position, ready to scan. The advantage: the user does not need to carry large, heavy spine coils any more and the patient preparation time is shortened. Additionally, by ensuring the correct positioning of the coil excellent image quality is also guarantied. The IsoCenter Matrix can be used in flexible combinations with other coils and works as a virtual 140 cm coil without patient repositioning in multi-step examinations.
Another new feature is the Focus Shoulder Array for optimum imaging of the shoulder. The coil's shim wing shifts the examination area of the magnet from the middle of the system to the shoulder, which would lie at the edge of the measuring volume without this technology.
Magnetom Essenza has a shorter system length than many conventional 1.5 Tesla MR systems. This means that the head and feet of the patient remain outside of the system in many cases, making the examination much more pleasant for the person in the bore.



Thursday, October 25, 2007

Kasabach-Merritt Syndrome

I came across this very intresting case by By: patricia burrows, Radiologist, Children's Hospital Boston, Massachusetts, USA

these are great MRI's of this Syndrome

Here is another good case

Thanks mypacsnet

General Discussion
Hemangioma-Thrombocytopenia Syndrome (also known as Kasabach-Merritt Syndrome) is a rare disorder characterized by an abnormal blood condition in which the low number of blood platelets causes bleeding (thrombocytopenia). The thrombocytopenia is found in association with a benign tumor consisting of large, blood-filled spaces (cavernous hemangioma). The exact cause of this disorder is not known.



Symptoms

Hemangioma-Thrombocytopenia Syndrome is a rare disorder that is typically characterized by a benign (non-cancerous) tumor consisting of large, blood- filled spaces (cavernous hemangioma). This tumor occurs along with a blood condition (thrombocytopenia) characterized by an abnormally low number of blood platelets which can cause excessive bleeding.Excessive bleeding (hemorrhaging) beneath the skin (purpura) typically develops within the first six weeks of life, but may appear later in childhood as the hemangioma increases in size. Usually there is only one hemangioma which is found on the neck, arms, legs, or trunk of the body. Less common are tumors of the internal organs which may be found on the tongue, thorax, spleen, liver, gastrointestinal tract or bones. Hemangiomas are rarely found internally and on the skin of the same patient.Thrombocytopenia may occur within the first month of life in association with a hemangioma of the outer layer of the placenta (placental chorioangioma) or large hemangiomas of the skin.Hemangiomas may become filled with blood (engorged) before a bleeding spell occurs. The cause of the bleeding is not certain, but it can be triggered by trauma.A decrease in the level of the oxygen carrying component of blood cells (hemoglobin), red blood cells (erythrocytes), and/or proteins in the blood that are part of the clotting process (prothrombin and fibrinogen) may also occur. However, fibrinogen deficiency usually affects older children and adults.CausesThe exact cause of Hemangioma-Thrombocytopenia Syndrome is not known. It is thought that the thrombocytopenia may be a result of platelet destruction which occurs in relationship to growth of the hemangioma. There is no evidence that the syndrome is hereditary.Affected PopulationsHemangioma-Thrombocytopenia Syndrome is a very rare disorder that affects males and females in equal numbers. Approximately one in every five hundred cases of people with hemangiomas have associated thrombocytopenia.Courtesy of NORD website: http://rarediseases.org/



11 month 22 day old male: 11-month-old with history of Kasabach-Merritt syndrome and left shoulder/arm hemangioma, presenting with thrombocytopenia. The patient is a full term spontaneous vaginal delivery with no complications during pregnancy. At six weeks of age at a well baby checkup, the patient was noted to have two small bruises on the left arm and deltoid region. At three months the patient's mother noticed increased area of bruising as well as two more bruises on the left shoulder area. Diagnosis was hemangioma which would resolve with time. A left shoulder incisional biopsy was consistent with hemangioma. In September of 1994 he was placed on Prednisone, 4 milligrams per kilograms per day. Prednisone initially resulted in improvement but then the hemangioma increased in size. The patient was first given platelets in September of 1994 for a platelet count of 22K. Mother estimates some 30 platelet transfusions since then, the last one being in December of 1994. The patient underwent three sessions of radiation treatment in December of 1994, and on December 22, 1994 the patient was admitted with the diagnosis of rectal prolapse, which was reduced. Cultures grew out Klebsiella and the patient was treated with Tobramycin and Timentin. The patient improved and was discharged. Interferon was begun in October of 1994, present dose is 0.3 milliliters subcutaneously q.d. Two urine samples of FgF showed on January 30, 1995 44,000, and on February 27th 32,000. Three days prior to admission the patient showed increased agitation. Hemangioma became darker and harder, and most recent complete blood count as of April 3, 1995 was a red blood cells of 4.53, hematocrit of 23.2, and platelet count of 5. The white blood cell count had a differential of 15 polys, 7 bands, 61 lymphs, 5 monos, 2 eosinophils. There has been no history of significant bleeding.

more info

Case study of IAC involvement.

Sunday, October 21, 2007

Robotic Arm. Inventor Dean Kamen

Inventor Dean Kamen discusses the next-generation prosthetic arm his engineers are building under contract from the Pentagon, and Boston Globe columnist Scott Kirsner gets a demo.
Dean Kamen has been working on robotic arms for injured soldiers who have lost limbs. The technology is like nothing we have ever seen before. He is being funded by a goverment agency (DARPA) and making great progress. The robotic arms will be able to have sensory perception along with motor control.



Wednesday, October 17, 2007

Cool Computers


Those itching for something off the beaten path should certainly look Sony's way, as the firm is offering up a few funky fresh items to celebrate its Canvas @ Sony art installation. Reportedly, the outfit will be selling a trio of stylish NW-A808 DAPs, MDR-KX70LW earbuds and VAIO VGN-CR90 laptops, all of which will boast unique, art-inspired enclosures. As for prices, the A808s will be ¥26,800 ($228) while the earbuds and laptops will ring up at ¥5,980 ($51) and ¥114,800 ($978), respectively. But you'd better get a move on, as each of the aforementioned items are limited in quantity to 100. Click on for more pictorial delight.[Via Impress]
Continue reading Sony cranks out artsy new audio gear, VAIO laptops

Tuesday, October 16, 2007

IVMRI TOPSPIN




The fate of the IntraVascular MRI (IVMRI) Catheter, a self-contained magnetic resonance system for visualization of coronary arteries from Israel's TopSpin Medical, is now in the hands of the FDA. We've been following this exciting technology since 2005. According to Globes, the company completed laboratory tests, preclinical and clinical trials for the catheter, and its CEO is quite optimistic about a possible US approval. The system has received the CE Mark from the European regulators back in December.
To remind our readers, here's how the technology works:
TopSpin Medical has developed a self contained "inside-out" miniature MRI probe in a tip of an intravascular catheter that allows for local high-resolution imaging of blood vessels without the need for external magnets or coils. The advantages of this technique range from the very practical aspect of a low-cost system (since no expensive external setup is required), accessibility to the patient during the procedure, compatibility with existing interventional tools, and finally resolution and diffusion contrast capabilities that are unattainable by conventional clinical MRI, due to the strong local gradients created by the probe and its proximity to the examined tissue.
The intravascular probe serves as a first example for a wide range of applications for this method, which in the near future may revolutionize the field of clinical MRI. It opens the door for the application of MRI in cases where high-resolution local images are required and when the transformation into an MRI environment is both mentally and economically difficult for the hospital. The medical applications for this technology include detection and staging of prostate cancer, imaging tumors in the colon, lung and breast and intravascular imaging of the peripheral vasculature...
A static magnetic field of about 0.2 Tesla is generated by strong permanent magnets located at the tip of the catheter. The gradients that result from such a small configuration are in the range of 100-300 T/m, and may be controlled to some extent by changing the angle of the magnetization and the dimensions of the gap between the two magnet pieces. Due to volume constraints, a single coil is used both for transmission and for reception. The magnetic field profile created by this "inside-out" probe within the imaged volume is significantly different from that created by conventional NMR or MRI setups.
The IVMRI catheter is used for measuring the apparent water diffusion coefficient of the various components of the atherosclerotic vascular wall. It shows decreased and isotropic water diffusion within the atherosclerotic plaque compared with the fibrous cap and medial layer. Hence, the heterogeneous water diffusion properties within the atherosclerotic arterial wall can be exploited, by the IVMRI catheter, to develop an index of arterial wall lipid infiltration and help determine the structure of the arterial wall with regard to lipid content. The extent and location of increased vascular lipid infiltration can then be used to determine the presence of an atherosclerotic lesion with an increased likelihood of subsequent clinical instability. The IVMRI catheter was designed to obtain high-resolution imaging, thereby revealing the depth and size of the necrotic core and assess fibrous cap thickness.
Globes: Topspin Medical applies to FDA for catheter approval ...
TopSpin Medical ...
Flashback: IntraVascular MRI (IVMRI) Catheter

Saturday, October 06, 2007

Cancer specialists warn EU directive puts MRI benefits at risk

MADRID (AFP) — Cancer researchers warned at a conference in Spain Monday that an EU directive on limiting magnetic resonance imaging (MRI) could halt use of an important tool in the fight against the disease.
The directive is set to be implemented across Europe by April next year and was drawn up to limit medical workers' exposure to electromagnetic fields.
But Professor Dag Rune Olsen, a specialist in experimental radiation therapy at the Norwegian Radiation Hospital in Oslo, told the European Cancer Conference in Barcelona that the directive could put at risk some eight million annual MRI scans, hampering patient treatment.
"These are likely to have to stop, since the directive sets limits to occupational radiation exposure which will mean that anyone working or moving near MRI equipment will breach them, thus making it possible for them to sue their employers," he said.
"Even those maintaining or servicing the equipment may be affected," said Olsen, who is also chairman of the physics committee of the European Society for Therapeutic Radiology and Oncology (ESTRO).
Britain's Health and Safety Executive published a study in June, undertaken by Professor Stuart Crozier of Brisbane University, Australia, which found that anyone standing within about one metre (yard) of an MRI scanner in use would breach the exposure limits laid down in the EU directive.
EU authorities are now considering amendments to the directive.
According to Professor Olsen, "Slovakia has already implemented the directive, on the grounds that it was based on the assumption that the limits which it sets would have no effect. This would appear to mean that it is now illegal to carry out MRI scanning in the country."
In a statement, conference organisers said the directive "will also stop the use of MRI for interventional and surgical procedures, and will curtail cutting edge research."
"The added value that MRI represents to medical diagnostics has been tremendous," Olsen insisted.
He said he hoped there could be a delay in the directive's implementation, while also warning against "hasty decisions without scientific support".
Professor John Smyth, president of the Federation of European Cancer Societies (FECS), meanwhile warned that political decisions were harming cancer treatment in Europe.
He cited the MRI directive as an example and said that "(it) looks as though it may stop all MRI scanning in Europe".
"We simply cannot continue to bury our heads in the sand on these issues, which affect doctors and patients alike," he said.
Earlier, the conference heard that the number of elderly cancer patients would likely double from 2000 to 2030, creating "huge challenges" to healthcare systems worldwide

Microsoft HealthVault Unveiled


Microsoft's long awaited and highly secretive health portal has been rolled out and is free for use by the public. HealthVault is essentially an online place to keep family's electronic medical records and easily share them with medical providers. What Microsoft claims to have done is effectively create an electronic filing cabinet and a built-in fax machine that can selectively share data found in the cabinet with anyone connected to the internet. Additionally, the system allows for connectivity with devices like blood pressure meters and glucose monitors, that can upload their data to the system for a physician to review and for historical reference.
We imagine that a system like this might be useful in reverse, where a physician uploads information for the rest of the family to see, as in cases like a child away at camp or parents that live at a distance who visit a clinic.
Currently in beta, Microsoft's HealthVault plans to stay free and to pay for itself through advertising on the built-in search engine.
HealthVault...

HEALTH SEARCH: The new way to search for healthcare articles, Web links, and mini-applications.
DIRECT INPUT: Enter your personal information, upload health documents, and create records for members of your family. It's time to digitize the doctor's office "clipboard".
FAX INPUT: Have your health records faxed directly into your HealthVault account. Collect all your paper-based health records into your digital store.

YOUR DOCTORS: Your whole healthcare provider team — from MDs to Chiropractors — are generating information about your health. You should have a copy of that information so that you can share it with all of them.
PRESCRIPTIONS: Medications need to be managed and renewed and, if your MD is e-prescribes, HealthVault can collect and store your medication history.
IMAGING & LAB RESULTS: Your images (X-Rays, MRIs, CAT Scans) and lab results may also be a part of your health record, and HealthVault helps you keep copies of them in your account.

Thursday, October 04, 2007

Astrocytoma & MRI









Cerebellar astrocytoma is the most common posterior fossa neoplasm in the child. Occasionally, these tumors present in young adults. Eighty-five percent are of the pilocytic type, which appear relatively well-circumscribed, are partially cystic and often contain a mural nodule of enhancing solid tissue. Pilocytic cerebellar astrocytomas uncommonly calcify (20%) and rarely hemorrhage. Hydrocephalus is often present, leading to patients' common presenting symptoms of nausea, vomiting, headache, or ataxia. There is an increased frequency of occurrence with neurofibromatosis type I. Pilocytic astrocytomas are associated with a 90-95% 25-year survival rate, the highest of all primary brain gliomas. The less common fibrillary astrocytoma comprises 15% of cerebellar astrocytomas. This subtype carries a worse prognosis and tends to be infiltrative.
Medulloblastoma is primarily a neoplasm of children but occurs in adults 30% of the time. Peak incidence is in the latter half of the first decade although a smaller second peak occurs in the early third decade. In young adults, medulloblastomas usually arise in the dorsal aspect of the lateral cerebellar hemispheres, as opposed to the characteristic origin from the cerebellar vermis in children. Medulloblastoma typically has a high CT density before intravenous contrast with dense enhancement after injection. On MRI, the long TR images usually demonstrate an isointense mass, rather than the hyperintensity seen in this case. Like other primitive neuroectodermal tumors (PNET), medulloblastomas have the propensity to disseminate into the subarachnoid space via cerebrospinal fluid (CSF) pathways. The occurrence of medulloblastomas has been associated with such heritable diseases as Gorlin's basal cell nevus syndrome, Turcot's glioma-polyposis syndrome, and ataxia-telangiectasia.

Ependymomas account for about 5% of all intracranial gliomas. They are most common in children under 5 years of age, but a smaller peak occurs at age 30 to 40 years. The fourth ventricle is the most common site, often leading to dilatation and extrusion of tumor through the various ventricular foramina. However, CSF seeding occurs less frequently compared to PNET tumors. Ependymomas appear heterogeneous on CT and MRI and often contain hemorrhagic foci. Calcification is present in about 40-50% of patients.

Hemangioblastomas of the posterior fossa usually occur spontaneously but are associated with von Hippel Lindau disease (vHL) in 4-20% of patients. With vHL, 20% of tumors are multiple and can occur anywhere in the cerebellum, brainstem, or spinal cord. Hemangioblastomas classically are cystic-appearing with an enhancing mural nodule, but they are entirely solid in 30-40% of patients. The tumors often have associated large vessels leading to the mass, best seen on gradient echo MRI.



Astrocytomas

By Patrick J. Kelly, M.D., FACS, Professor and Chairman of Neurosurgery

Glial Neoplasms comprise the majority of primary intracranial tumors. These affect about 14,000 Americans annually. Glial tumors are divided into a classification scheme based on cell type-usually based on the supposed cell of origin. Thus, astrocytomas are derived from astrocytes, Oligodendrogliomas derived from oligodendroglial cells and mixed gliomas or oligoastrocytomas are derived from both astrocytes and oligodendroglial elements. The following discussion concerns astrocytomas only and is presented in hopes that it will provide some insight into the classification and treatment of these tumors.

Types

In general astrocytic tumors are classified according to histologic grade. There is some confusion among pathologists on the proper system for tumor grading. This can result in confusion for physicians, research protocols and especially for patients. Below I will try to clarify the classification issue as this is extremely important for understanding the tumor and its prognosis.

The astrocytoma is derived from a normal supporting cell in the brain called the astrocyte. In a patient with one of these tumors, the cells in the astrocytoma tumor are no longer normal; and the degree of this abnormality is used to determine the tumor's grade. The tumor's grade determines the prognosis of the tumor. Astrocytomas are graded from 1 to 4, with grade 1 being the slowest growing and grade 4 being the most rapidly growing and malignant lesions. The following descriptions refer to the appearance of the tumor under the pathologist's microscope.

Grade 1: In these tumors astrocytic tumor cells are usually normal in appearance except that there are more of them than normally seen in microscopic examinations of brain tissue. Usually grade 1 astrocytomas produce epileptic seizures as their only symptom since their presence is irritating to surrounding brain tissue. They can also become quite large since they are well tolerated by the brain. However, when the mass effect of the tumor and the mass of the brain combine within the non-yielding skull cavity; a rise in pressure inside the skull results. This can cause headaches, paralysis, personality change, coma and death. The prognosis for grade 1 astrocytomas is generally good. Sometimes surgery to reduce mass effect is required, however. Patients with grade 1 astrocytomas have been known to live 30 years or more following diagnosis. Radiation therapy is probably not appropriate in these tumors.



Pilocytic astrocytomas: These benign astrocytomas tend to occur in children and young adults, are histologically circumscribed . Despite the fact that many are located in the thalamus and other important subcortical locations, they can be completely resected by computer assisted stereotactic technique with excellent postoperative results. These lesions exhibit prominent enhancementon CT or on MR imaging with gadolinium
Grade 2: In grade 2 tumors, tumor cells are slightly abnormal in appearance as well as increased in number. The variations in appearance of these cells is referred to as pleomorphism. There should be no mitotic figures (indications that the cells are dividing) and no necrosis (dead tissue). In general, these tumors are made up of isolated tumor cells within functioning brain tissue. On imaging studies these lesions show hypodensity on CT and prolongation of T1 and T2 on MRI, They only very rarely exhibit contrast enhancement.Removal of the tumor is, in fact, removal of this "sick" brain tissue. These tumors are, therefore, usually biopsied only; unless they are located in unimportant brain tissue- in which case they can be removed

There remains some debate on the place for radiation therapy and chemotherapy in these tumors. However, recent studies have shown that 5 year survival in grade 2 astrocytomas without treatment is about 34%; and with treatment (radiation therapy): about 70%. Therefore most centers recommend radiation therapy after a grade 2 astrocytoma is diagnosed by biopsy or some other surgical procedure.




Grade 3: These and Grade 4 astrocytomas are frequently referred to as malignant astrocytomas. They exhibit contrast enhancement on imaging studies. Frequently, the contrast enhancing mass is surrounded by a zone of hypodensity on CT and prolonged T1 and T2 on MRI as shown in Figure 4. This zone is frequently called "edema" and it is edematous brain parenchyma infiltrated by isolated tumor cells.
In another classification scheme these are referred to as anaplastic astrocytomas. In grade 3 tumors, cells are not only abnormal in appearance but some show evidence of mitosis. Mitosis is the cellular process by which cells divide; where one cell becomes two. Mitoses are apparent to the pathologist as the surgical specimen is reviewed under the microscope. Some of the cells in the tumor infiltrate into brain tissue- similar to the picture seen with grade 1 and grade 2 astrocytomas; other cells stay put and continue to divide and destroy the brain parenchyma in which they reside as the joined cells for a mass of solid tumor tissue. When the tumor tissue is formed in important brain areas, neurological deficits corresponding to that area result because the brain tissue in that area is destroyed by the evolving tumor tissue mass. For example, a grade 3 astrocytoma forming in the central area of the brain, with formation of solid tumor tissue in the motor area will produceweakness and paralysis on the opposite side of the patient's body ( remember that the left side of the brain controls the right side of the body and vice versa).

Treatment for grade 3 astrocytomas involves establishing the diagnosis by surgery or stereotactic biopsy and follow-up with radiation therapy and chemotherapy. The average survival of patients with grade 3 astrocytomas is 18 months with treatment.

Grade 4: Grade 4 astrocytomas ( frequently referred to as glioblastomas or glioblastoma multiforme) are the most malignant variety of these tumors. They are made up of cells which infiltrate brain tissue with a region (and in some cases regions) of solid tumor tissue within the zone of infiltrated brain tissue. Mitoses are frequently noted by the pathologist as the surgical specimen is examined. In addition, regions of necrosis (dead tissue) are also noted- where the tumor has grown so fast that parts of it has outpaced itsblood supply. These tumors induce the formation of new but abnormal blood vessels which when identified are also important in establishing the diagnosis. The CT and MRI demonstrate a contrast enhancing mass with a hypodense center (which corresponds to necrosis) surrounded by a zone of hypodensity on CT and prolonged T1 and T2 on MRI which corresponds to infiltrated parenchyma as shown in Figure 5.

The grade 4 astrocytoma has the worst prognosis of all: 17 weeks average (mean) survival after diagnosis without treatment; 30 weeks average survival with biopsy followed by radiation therapy; 37 weeks average survival following surgical removal of most of the tumor tissue component of the tumor and radiation therapy and 51 weeks average survival following stereotactic volumetric resection of the tumor tissue component and radiation therapy. The prognosis for any patient with a malignant astrocytoma (grade 3 or 4) is also very dependent upon age (older people do not live as long as young patients) and performance status ( patients who are neurologically normal and independent live longer than patients who have a neurological deficit). Chemotherapy has been shown to add several weeks on to the survival. Radiation implants (brachytherapy) have also been shown to increase survival but more than half of these patients require another operation to remove dead tissue resulting from the radiation.

Therapy for Astrocytomas

With only a few exceptions (notably, pilocytic astrocytomas) astrocytomas are not curable tumors with any of the treatment methods available to us today. These treatment modalities consist of surgery which establishes the diagnosis and in some cases can remove a significant part of the tumor, radiation therapy, usually given in daily "fractions" of about 200 rads per day (5 days a week) over a 6 week course and chemotherapy ( many agents are available and being evaluated in many clinical "trials" around North America).

Surgical Procedures

Conventional Craniotomy with internal decompression

Here the patient's skull is opened and a surgeon guided by his own hand-eye coordination, knowledge of anatomy, qualitative interpretation of the CT and/or MRI and the appearance of the lesion from normal brain attempts to remove as much of the tumor as possible.The goals are to reduce intracranial pressure and reduce tumor burden.

Stereotactic Biopsy

A probe is inserted by means of a stereotactic frame into the CT and/or MRI defined tumor target in an attempt to obtain a specimen of the lesion for histologic diagnosis.

Stereotactic Volumetric Resection

This is a less invasive procedure than a conventional craniotomy. A virtual tumor volume (determined by the CT and MRI defined boundaries of the lesion) is established in a computer. The surgical procedure is simulated on the computer beforehand to determine the safest and most effective surgical approach. At surgery an opening in the skull is much smaller than with other types of neurosurgery and the removal of the tumor is guided by computer generated images, usually transmitted into a heads-up display unit mounted on the operating microscope. These computer generated images are superimposed over the surgical field and indicate to the surgeon where tumor stops and normal brain tissue begins. This helps the surgeon establish a plane between tumor and brain tissue for a more complete (and safer) removal of the lesion.

Radiation Therapy

Conventional External Beam: Modern radiation therapy for astrocytomas is delivered in multiple fractions by means of a linear accelerator (LINAC) . A planning CT or MRI scan is done to assist in targeting the radiation beams from the LINAC to encompass tumor plus a 2-3cm margin. Although there are variations in protocols between institutions, most patients receive between 6000 and 6500 rads delivered over a six week period of time (5 days per week).

Stereotactic Interstitial Irradiation: Radiation is delivered to a CT and/or MRI defined tumor volume by means of multiple stereotactically implanted radiation seeds (Iridium 192, Iodine 125, Palladium 103). Acting together these radionuclide sources produce a radiation dose field which is fitted to the volume of the tumor so that the tumor gets a lethal dose of radiation while the surrounding brain tissue receives much less because of the dose fall-off away from the sources. Radiation is delivered in a lower dose rate (typically 40 to 50 rads per hour) than in conventional external beam irradiation (200 rads per minute) which is theoretically safer for normal brain tissue surrounding the tumor. However, this form of radiation requires a surgical procedure to place the sources and they are frequently removed after the desired dose of radiation has been delivered. Commonly, interstitial irradiation is used as a "boost" to the radiation doses delivered by external beam radiation therapy.

Stereotactic Radiation Therapy: This type of external beam radiation therapy is delivered by a LINAC in multiple fractions but with the patient's head secured in a relocatable stereotactic frame which increases the accuracy.
Chemotherapy
There are many chemotherapy protocols under investigation in Phase II and Phase III clinical trials. Chemotherapy is usually considered in patients who have tolerated surgery and radiation therapy. Standard chemotherapeutic agents include BCNU, Procarbazine and Cisplatin. These will be discussed in further installments.

There are many experimental therapies- none of which have been shown to be curative yet. These include brachytherapy (stereotactic interstitial irradiation), stereotactic radiosurgery (focused one shot high dose irradiation to the tumor), immunotherapy (where lymphocytes conditioned to attack brain tumor cells are injected into the tumor or cavity made by surgical removal of part of the tumor) and most recently gene therapy ( where the brain is infected by a genetically engineered virus which attacks tumor cells). Clinical trials are underway for the evaluation of all of these.

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MRI Nueroarm Video