HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Schwartz, R. B. Articles by Jolesz, F. A. Search for Related Content PubMed PubMed Citation Articles by Schwartz, R. B. Articles by Jolesz, F. A.

Intraoperative MR Imaging Guidance for Intracranial Neurosurgery: Experience with the First 200 Cases¹

¹ From the Depts of Radiology (R.B.S., L.H., T.Z.W., D.F.K., A.A.Z., R.K., F.A.J.) and Surgery, Div of Neurosurgery (P.M.B., E.A., P.E.S., T.M.M., C.A.M.), Brigham and Women's Hospital, 75 Francis St, Boston, MA 02115. From the 1997 RSNA scientific assembly. Received Mar 18, 1998; revision requested May 14; revision received Aug 12; accepted Oct 26. Supported in part by NIH grants PO1 CA 67165, P41 RR13218, R01 RR11747, and R01 CA 45743 and by the National Science Foundation. Address reprint requests to R.B.S.

View larger version (94K): [in a new window]   Figure 1a. Open-bore MR imaging system in the operating suite. (a) The 56-cm-wide gap in the magnet allows surgeons access to the patient. Two liquid crystal display screens (arrow) are positioned overhead to allow the radiologist to indicate the surgical approach to the surgeon. Plugs for the head lamps and the hand-held navigation device are located on the right half of the magnet. (b) View through the bore of the open-configuration MR imaging system shows the fixed portion of the Mayfield head frame (arrow) attached to the table. The MR-compatible anesthesia system is located to the right of the magnet.

View larger version (107K): [in a new window]   Figure 1b. Open-bore MR imaging system in the operating suite. (a) The 56-cm-wide gap in the magnet allows surgeons access to the patient. Two liquid crystal display screens (arrow) are positioned overhead to allow the radiologist to indicate the surgical approach to the surgeon. Plugs for the head lamps and the hand-held navigation device are located on the right half of the magnet. (b) View through the bore of the open-configuration MR imaging system shows the fixed portion of the Mayfield head frame (arrow) attached to the table. The MR-compatible anesthesia system is located to the right of the magnet.

View larger version (108K): [in a new window]   Figure 2. Hand-held optical tracking device. Note the three light-emitting diodes located at the ends of the arms of the device; these are used to establish both the plane of imaging and the proposed trajectory of a needle placed through the center (arrow) of the device. The cable consists of a shielded copper wire surrounded by a plastic covering.

View larger version (139K): [in a new window]   Figure 3a. T1-weighted MR images (400/17, one signal acquired) obtained during biopsy of an intracranial mass in a 42-year-old immunosuppressed man with left-sided weakness show an irregular 2.5-cm-diameter ring-enhancing lesion adjacent to the right frontal horn. The lesion was localized by using the interactive hand-held navigational system. (a) Axial image shows the projected biopsy site (x). (b, c) Serial sagittal images show the planned trajectory (dashed line) of the needle and the needle itself (arrow) as it is gradually advanced (b) toward and (c) into the lesion. (d) Axial and (e) coronal MR images obtained after the biopsy show air (arrow) in the lesion (x), which verifies the accuracy of the biopsy. Histopathologic analysis demonstrated non-Hodgkin lymphoma. The dashed line in b–d indicates the needle trajectory; the junction between the long and short dashes indicates the location of "virtual" needle tip.

View larger version (121K): [in a new window]   Figure 3b. T1-weighted MR images (400/17, one signal acquired) obtained during biopsy of an intracranial mass in a 42-year-old immunosuppressed man with left-sided weakness show an irregular 2.5-cm-diameter ring-enhancing lesion adjacent to the right frontal horn. The lesion was localized by using the interactive hand-held navigational system. (a) Axial image shows the projected biopsy site (x). (b, c) Serial sagittal images show the planned trajectory (dashed line) of the needle and the needle itself (arrow) as it is gradually advanced (b) toward and (c) into the lesion. (d) Axial and (e) coronal MR images obtained after the biopsy show air (arrow) in the lesion (x), which verifies the accuracy of the biopsy. Histopathologic analysis demonstrated non-Hodgkin lymphoma. The dashed line in b–d indicates the needle trajectory; the junction between the long and short dashes indicates the location of "virtual" needle tip.

View larger version (120K): [in a new window]   Figure 3c. T1-weighted MR images (400/17, one signal acquired) obtained during biopsy of an intracranial mass in a 42-year-old immunosuppressed man with left-sided weakness show an irregular 2.5-cm-diameter ring-enhancing lesion adjacent to the right frontal horn. The lesion was localized by using the interactive hand-held navigational system. (a) Axial image shows the projected biopsy site (x). (b, c) Serial sagittal images show the planned trajectory (dashed line) of the needle and the needle itself (arrow) as it is gradually advanced (b) toward and (c) into the lesion. (d) Axial and (e) coronal MR images obtained after the biopsy show air (arrow) in the lesion (x), which verifies the accuracy of the biopsy. Histopathologic analysis demonstrated non-Hodgkin lymphoma. The dashed line in b–d indicates the needle trajectory; the junction between the long and short dashes indicates the location of "virtual" needle tip.

View larger version (131K): [in a new window]   Figure 3d. T1-weighted MR images (400/17, one signal acquired) obtained during biopsy of an intracranial mass in a 42-year-old immunosuppressed man with left-sided weakness show an irregular 2.5-cm-diameter ring-enhancing lesion adjacent to the right frontal horn. The lesion was localized by using the interactive hand-held navigational system. (a) Axial image shows the projected biopsy site (x). (b, c) Serial sagittal images show the planned trajectory (dashed line) of the needle and the needle itself (arrow) as it is gradually advanced (b) toward and (c) into the lesion. (d) Axial and (e) coronal MR images obtained after the biopsy show air (arrow) in the lesion (x), which verifies the accuracy of the biopsy. Histopathologic analysis demonstrated non-Hodgkin lymphoma. The dashed line in b–d indicates the needle trajectory; the junction between the long and short dashes indicates the location of "virtual" needle tip.

View larger version (116K): [in a new window]   Figure 3e. T1-weighted MR images (400/17, one signal acquired) obtained during biopsy of an intracranial mass in a 42-year-old immunosuppressed man with left-sided weakness show an irregular 2.5-cm-diameter ring-enhancing lesion adjacent to the right frontal horn. The lesion was localized by using the interactive hand-held navigational system. (a) Axial image shows the projected biopsy site (x). (b, c) Serial sagittal images show the planned trajectory (dashed line) of the needle and the needle itself (arrow) as it is gradually advanced (b) toward and (c) into the lesion. (d) Axial and (e) coronal MR images obtained after the biopsy show air (arrow) in the lesion (x), which verifies the accuracy of the biopsy. Histopathologic analysis demonstrated non-Hodgkin lymphoma. The dashed line in b–d indicates the needle trajectory; the junction between the long and short dashes indicates the location of "virtual" needle tip.

View larger version (137K): [in a new window]   Figure 4a. T2-weighted (4,000/85, two signals acquired) MR imaging–guided resection of a low-grade astrocytoma in a 40-year-old man with recent onset of seizures. (a) Coronal MR image shows a well-defined high-signal-intensity abnormality (large arrow) in the left frontal lobe; a capsule containing cod-liver oil (small arrow) has been placed on the scalp to demarcate the inferior border of the lesion, in preparation for craniotomy. (b) Axial MR image shows a well-defined high-signal-intensity abnormality (large arrow) in the left frontal lobe; a capsule containing cod-liver oil (small arrow) has been placed on the scalp to demarcate the posterior border of the lesion, in preparation for craniotomy. (c) Axial MR image shows the site of craniotomy (arrows), which was performed under MR imaging guidance. (d) Axial MR image shows that after the dura was removed, abnormal tissue (arrow) herniated through the craniotomy, distorting the preoperative anatomy. MR imaging allowed the radiologist and surgeons to compensate for this anatomic change. (e) Axial MR image shows that after the bulk of the lesion was removed, a small focus of residual tumor, not readily visible to the surgeon, was demarcated with a tuberculin syringe filled with saline solution (long arrow), which acted as a high-signal-intensity pointer. Owing to the proximity of the lesion to the motor strip (short arrow), the tumor was not resected.

View larger version (101K): [in a new window]   Figure 4b. T2-weighted (4,000/85, two signals acquired) MR imaging–guided resection of a low-grade astrocytoma in a 40-year-old man with recent onset of seizures. (a) Coronal MR image shows a well-defined high-signal-intensity abnormality (large arrow) in the left frontal lobe; a capsule containing cod-liver oil (small arrow) has been placed on the scalp to demarcate the inferior border of the lesion, in preparation for craniotomy. (b) Axial MR image shows a well-defined high-signal-intensity abnormality (large arrow) in the left frontal lobe; a capsule containing cod-liver oil (small arrow) has been placed on the scalp to demarcate the posterior border of the lesion, in preparation for craniotomy. (c) Axial MR image shows the site of craniotomy (arrows), which was performed under MR imaging guidance. (d) Axial MR image shows that after the dura was removed, abnormal tissue (arrow) herniated through the craniotomy, distorting the preoperative anatomy. MR imaging allowed the radiologist and surgeons to compensate for this anatomic change. (e) Axial MR image shows that after the bulk of the lesion was removed, a small focus of residual tumor, not readily visible to the surgeon, was demarcated with a tuberculin syringe filled with saline solution (long arrow), which acted as a high-signal-intensity pointer. Owing to the proximity of the lesion to the motor strip (short arrow), the tumor was not resected.

View larger version (109K): [in a new window]   Figure 4c. T2-weighted (4,000/85, two signals acquired) MR imaging–guided resection of a low-grade astrocytoma in a 40-year-old man with recent onset of seizures. (a) Coronal MR image shows a well-defined high-signal-intensity abnormality (large arrow) in the left frontal lobe; a capsule containing cod-liver oil (small arrow) has been placed on the scalp to demarcate the inferior border of the lesion, in preparation for craniotomy. (b) Axial MR image shows a well-defined high-signal-intensity abnormality (large arrow) in the left frontal lobe; a capsule containing cod-liver oil (small arrow) has been placed on the scalp to demarcate the posterior border of the lesion, in preparation for craniotomy. (c) Axial MR image shows the site of craniotomy (arrows), which was performed under MR imaging guidance. (d) Axial MR image shows that after the dura was removed, abnormal tissue (arrow) herniated through the craniotomy, distorting the preoperative anatomy. MR imaging allowed the radiologist and surgeons to compensate for this anatomic change. (e) Axial MR image shows that after the bulk of the lesion was removed, a small focus of residual tumor, not readily visible to the surgeon, was demarcated with a tuberculin syringe filled with saline solution (long arrow), which acted as a high-signal-intensity pointer. Owing to the proximity of the lesion to the motor strip (short arrow), the tumor was not resected.

View larger version (91K): [in a new window]   Figure 4d. T2-weighted (4,000/85, two signals acquired) MR imaging–guided resection of a low-grade astrocytoma in a 40-year-old man with recent onset of seizures. (a) Coronal MR image shows a well-defined high-signal-intensity abnormality (large arrow) in the left frontal lobe; a capsule containing cod-liver oil (small arrow) has been placed on the scalp to demarcate the inferior border of the lesion, in preparation for craniotomy. (b) Axial MR image shows a well-defined high-signal-intensity abnormality (large arrow) in the left frontal lobe; a capsule containing cod-liver oil (small arrow) has been placed on the scalp to demarcate the posterior border of the lesion, in preparation for craniotomy. (c) Axial MR image shows the site of craniotomy (arrows), which was performed under MR imaging guidance. (d) Axial MR image shows that after the dura was removed, abnormal tissue (arrow) herniated through the craniotomy, distorting the preoperative anatomy. MR imaging allowed the radiologist and surgeons to compensate for this anatomic change. (e) Axial MR image shows that after the bulk of the lesion was removed, a small focus of residual tumor, not readily visible to the surgeon, was demarcated with a tuberculin syringe filled with saline solution (long arrow), which acted as a high-signal-intensity pointer. Owing to the proximity of the lesion to the motor strip (short arrow), the tumor was not resected.

View larger version (105K): [in a new window]   Figure 4e. T2-weighted (4,000/85, two signals acquired) MR imaging–guided resection of a low-grade astrocytoma in a 40-year-old man with recent onset of seizures. (a) Coronal MR image shows a well-defined high-signal-intensity abnormality (large arrow) in the left frontal lobe; a capsule containing cod-liver oil (small arrow) has been placed on the scalp to demarcate the inferior border of the lesion, in preparation for craniotomy. (b) Axial MR image shows a well-defined high-signal-intensity abnormality (large arrow) in the left frontal lobe; a capsule containing cod-liver oil (small arrow) has been placed on the scalp to demarcate the posterior border of the lesion, in preparation for craniotomy. (c) Axial MR image shows the site of craniotomy (arrows), which was performed under MR imaging guidance. (d) Axial MR image shows that after the dura was removed, abnormal tissue (arrow) herniated through the craniotomy, distorting the preoperative anatomy. MR imaging allowed the radiologist and surgeons to compensate for this anatomic change. (e) Axial MR image shows that after the bulk of the lesion was removed, a small focus of residual tumor, not readily visible to the surgeon, was demarcated with a tuberculin syringe filled with saline solution (long arrow), which acted as a high-signal-intensity pointer. Owing to the proximity of the lesion to the motor strip (short arrow), the tumor was not resected.

View larger version (45K): [in a new window]   Figure 5a. Dynamic contrast-enhanced MR imaging–guided resection of possible recurrence of intracranial metastatic disease in a 64-year-old woman. The patient had a recent onset of headaches and progressive visual loss in the left visual field 15 months after undergoing high-dose radiation therapy for an intracranial metastasis from lung cancer. MR imaging demonstrated an irregularly shaped enhancing lesion in the left occipital lobe, which represented a combination of recurrent tumor and gliosis due to radiation changes. The patient is prone. (a) Axial two-dimensional fast spoiled gradient-echo MR image (minimum echo time; flip angle, 45°; section thickness, 5 mm; one signal acquired; acquisition time, 1.87 seconds per image) obtained immediately after bolus injection of 20 mL of 0.5 mol/L gadopentetate dimeglumine. A pixel-by-pixel curve fit was performed, and the data were color coded according to the parameters of the fit. This color map has been superimposed on an axial T1-weighted image (600/29, two signals acquired). Foci of early enhancement are shown in magenta, which indicates the likely presence of recurrent tumor. (b) Axial T1-weighted image (600/29, two signals acquired) obtained, with the patient in the prone position, after partial resection of the treated tumor bed. A tuberculin syringe (arrow) filled with the patient's gadolinium-enhanced blood acts as a high-signal-intensity pointer and indicates a focus of early enhancement in the treated tumor bed. Histopathologic analysis demonstrated recurrent metastatic tumor.

View larger version (67K): [in a new window]   Figure 5b. Dynamic contrast-enhanced MR imaging–guided resection of possible recurrence of intracranial metastatic disease in a 64-year-old woman. The patient had a recent onset of headaches and progressive visual loss in the left visual field 15 months after undergoing high-dose radiation therapy for an intracranial metastasis from lung cancer. MR imaging demonstrated an irregularly shaped enhancing lesion in the left occipital lobe, which represented a combination of recurrent tumor and gliosis due to radiation changes. The patient is prone. (a) Axial two-dimensional fast spoiled gradient-echo MR image (minimum echo time; flip angle, 45°; section thickness, 5 mm; one signal acquired; acquisition time, 1.87 seconds per image) obtained immediately after bolus injection of 20 mL of 0.5 mol/L gadopentetate dimeglumine. A pixel-by-pixel curve fit was performed, and the data were color coded according to the parameters of the fit. This color map has been superimposed on an axial T1-weighted image (600/29, two signals acquired). Foci of early enhancement are shown in magenta, which indicates the likely presence of recurrent tumor. (b) Axial T1-weighted image (600/29, two signals acquired) obtained, with the patient in the prone position, after partial resection of the treated tumor bed. A tuberculin syringe (arrow) filled with the patient's gadolinium-enhanced blood acts as a high-signal-intensity pointer and indicates a focus of early enhancement in the treated tumor bed. Histopathologic analysis demonstrated recurrent metastatic tumor.

View larger version (144K): [in a new window]   Figure 6a. Axial T1-weighted intraoperative MR images (600/29, two signals acquired) of resection of treated glioblastoma multiforme in a 54-year-old woman show the appearance of various artifacts. (a) Image obtained after a craniotomy was performed shows a heterogeneously enhancing mass in the right frontal lobe. The tip of the surgeon's gloved finger (arrow) demarcates the medial portion of the tumor bed. (b) During the course of the resection, air in the subdural space has caused brain to shift away from the skull and compress the right lateral ventricle (arrow). With conventional stereotactic methods, this intraoperative shift of brain structures cannot be predicted. (c) Image obtained through the inferior portion of the tumor bed shows a cotton ball (arrow), which was placed in the resection cavity to absorb blood. (d) Image obtained after the enhancing tissue was removed (histopathologic analysis demonstrated a combination of gliosis and residual tumor) shows iodine 125 radiation seeds (arrows) that were implanted under MR imaging guidance.

View larger version (144K): [in a new window]   Figure 6b. Axial T1-weighted intraoperative MR images (600/29, two signals acquired) of resection of treated glioblastoma multiforme in a 54-year-old woman show the appearance of various artifacts. (a) Image obtained after a craniotomy was performed shows a heterogeneously enhancing mass in the right frontal lobe. The tip of the surgeon's gloved finger (arrow) demarcates the medial portion of the tumor bed. (b) During the course of the resection, air in the subdural space has caused brain to shift away from the skull and compress the right lateral ventricle (arrow). With conventional stereotactic methods, this intraoperative shift of brain structures cannot be predicted. (c) Image obtained through the inferior portion of the tumor bed shows a cotton ball (arrow), which was placed in the resection cavity to absorb blood. (d) Image obtained after the enhancing tissue was removed (histopathologic analysis demonstrated a combination of gliosis and residual tumor) shows iodine 125 radiation seeds (arrows) that were implanted under MR imaging guidance.

View larger version (147K): [in a new window]   Figure 6c. Axial T1-weighted intraoperative MR images (600/29, two signals acquired) of resection of treated glioblastoma multiforme in a 54-year-old woman show the appearance of various artifacts. (a) Image obtained after a craniotomy was performed shows a heterogeneously enhancing mass in the right frontal lobe. The tip of the surgeon's gloved finger (arrow) demarcates the medial portion of the tumor bed. (b) During the course of the resection, air in the subdural space has caused brain to shift away from the skull and compress the right lateral ventricle (arrow). With conventional stereotactic methods, this intraoperative shift of brain structures cannot be predicted. (c) Image obtained through the inferior portion of the tumor bed shows a cotton ball (arrow), which was placed in the resection cavity to absorb blood. (d) Image obtained after the enhancing tissue was removed (histopathologic analysis demonstrated a combination of gliosis and residual tumor) shows iodine 125 radiation seeds (arrows) that were implanted under MR imaging guidance.

View larger version (133K): [in a new window]   Figure 6d. Axial T1-weighted intraoperative MR images (600/29, two signals acquired) of resection of treated glioblastoma multiforme in a 54-year-old woman show the appearance of various artifacts. (a) Image obtained after a craniotomy was performed shows a heterogeneously enhancing mass in the right frontal lobe. The tip of the surgeon's gloved finger (arrow) demarcates the medial portion of the tumor bed. (b) During the course of the resection, air in the subdural space has caused brain to shift away from the skull and compress the right lateral ventricle (arrow). With conventional stereotactic methods, this intraoperative shift of brain structures cannot be predicted. (c) Image obtained through the inferior portion of the tumor bed shows a cotton ball (arrow), which was placed in the resection cavity to absorb blood. (d) Image obtained after the enhancing tissue was removed (histopathologic analysis demonstrated a combination of gliosis and residual tumor) shows iodine 125 radiation seeds (arrows) that were implanted under MR imaging guidance.

View larger version (99K): [in a new window]   Figure 7a. Sagittal T1-weighted MR images (600/29, two signals acquired) show an intracranial cyst in a 34-year-old man. The cyst was localized and drained under intraoperative MR imaging guidance. (a) A supracerebellar cystic collection (arrow) is visible. The surgeon's gloved finger is pointing toward the lesion, demarcating the planned trajectory of the needle for drainage. (b) After 0.1 mL of 0.5 mol/L gadopentetate dimeglumine (curved arrow) was injected into the cyst, no communication with the surrounding CSF was demonstrated. An intracranial catheter (straight arrows) was used to drain the cyst under MR imaging guidance.

View larger version (104K): [in a new window]   Figure 7b. Sagittal T1-weighted MR images (600/29, two signals acquired) show an intracranial cyst in a 34-year-old man. The cyst was localized and drained under intraoperative MR imaging guidance. (a) A supracerebellar cystic collection (arrow) is visible. The surgeon's gloved finger is pointing toward the lesion, demarcating the planned trajectory of the needle for drainage. (b) After 0.1 mL of 0.5 mol/L gadopentetate dimeglumine (curved arrow) was injected into the cyst, no communication with the surrounding CSF was demonstrated. An intracranial catheter (straight arrows) was used to drain the cyst under MR imaging guidance.

View larger version (110K): [in a new window]   Figure 8a. Sagittal T1-weighted (500/20, two signals acquired) MR imaging–guided resection of pituitary macroadenoma in a 42-year-old man. The patient is supine, with the head oriented in the right decubitus position. (a) Contrast-enhanced MR image shows a 2-cm enhancing mass in the sella turcica (white arrow). Note the metallic artifact from the titanium nasal speculum (black arrow). (b) MR image obtained after resection of the mass shows a sterile compressed sponge (arrow) packed into the surgical site.

View larger version (111K): [in a new window]   Figure 8b. Sagittal T1-weighted (500/20, two signals acquired) MR imaging–guided resection of pituitary macroadenoma in a 42-year-old man. The patient is supine, with the head oriented in the right decubitus position. (a) Contrast-enhanced MR image shows a 2-cm enhancing mass in the sella turcica (white arrow). Note the metallic artifact from the titanium nasal speculum (black arrow). (b) MR image obtained after resection of the mass shows a sterile compressed sponge (arrow) packed into the surgical site.

View larger version (128K): [in a new window]   Figure 9a. Hyperacute hemorrhage in a 19-year-old woman after resection of a low-grade astrocytoma. (a) Axial T1-weighted (600/29, two signals acquired) nonenhanced MR image obtained immediately after surgery shows an area of heterogeneous and predominantly isointense signal in a surgical cavity (arrow). (b) Axial T2-weighted (4,000/85, two signals acquired) MR image obtained immediately after surgery shows an area of heterogeneous and predominantly isointense signal intensity in a surgical cavity (arrow). (c) Axial gradient-recalled-echo MR image (600/9, 30° flip angle) shows several small foci of low T2 signal intensity (arrow). (d) On the longer echo time gradient-recalled-echo MR image (600/60, 30° flip angle), these foci bloom because of a hyperacute blood collection (arrow) that was not evident on the conventional MR images.

View larger version (133K): [in a new window]   Figure 9b. Hyperacute hemorrhage in a 19-year-old woman after resection of a low-grade astrocytoma. (a) Axial T1-weighted (600/29, two signals acquired) nonenhanced MR image obtained immediately after surgery shows an area of heterogeneous and predominantly isointense signal in a surgical cavity (arrow). (b) Axial T2-weighted (4,000/85, two signals acquired) MR image obtained immediately after surgery shows an area of heterogeneous and predominantly isointense signal intensity in a surgical cavity (arrow). (c) Axial gradient-recalled-echo MR image (600/9, 30° flip angle) shows several small foci of low T2 signal intensity (arrow). (d) On the longer echo time gradient-recalled-echo MR image (600/60, 30° flip angle), these foci bloom because of a hyperacute blood collection (arrow) that was not evident on the conventional MR images.

View larger version (98K): [in a new window]   Figure 9c. Hyperacute hemorrhage in a 19-year-old woman after resection of a low-grade astrocytoma. (a) Axial T1-weighted (600/29, two signals acquired) nonenhanced MR image obtained immediately after surgery shows an area of heterogeneous and predominantly isointense signal in a surgical cavity (arrow). (b) Axial T2-weighted (4,000/85, two signals acquired) MR image obtained immediately after surgery shows an area of heterogeneous and predominantly isointense signal intensity in a surgical cavity (arrow). (c) Axial gradient-recalled-echo MR image (600/9, 30° flip angle) shows several small foci of low T2 signal intensity (arrow). (d) On the longer echo time gradient-recalled-echo MR image (600/60, 30° flip angle), these foci bloom because of a hyperacute blood collection (arrow) that was not evident on the conventional MR images.

View larger version (86K): [in a new window]   Figure 9d. Hyperacute hemorrhage in a 19-year-old woman after resection of a low-grade astrocytoma. (a) Axial T1-weighted (600/29, two signals acquired) nonenhanced MR image obtained immediately after surgery shows an area of heterogeneous and predominantly isointense signal in a surgical cavity (arrow). (b) Axial T2-weighted (4,000/85, two signals acquired) MR image obtained immediately after surgery shows an area of heterogeneous and predominantly isointense signal intensity in a surgical cavity (arrow). (c) Axial gradient-recalled-echo MR image (600/9, 30° flip angle) shows several small foci of low T2 signal intensity (arrow). (d) On the longer echo time gradient-recalled-echo MR image (600/60, 30° flip angle), these foci bloom because of a hyperacute blood collection (arrow) that was not evident on the conventional MR images.