SANS Januari 2014 Flashcards
Diffusion tensor imaging bergantung kepada perbedaan mengukur dalam directional diffusion dari molekul air pada jaringan. Direction-dependent diffusion ini disebut apakah ?
A. Axial diffusivity B. Anisotropy C. Apparent diffusion coefficient D. Mean diffusivity E. Radial diffusivity
B. Anisotropy
The correct answer is anisotropy, which refers to the direction-dependent difference of molecular diffusion in tissue. In white matter, anisotropy is high, because water molecules are much more likely to diffuse along the axis of a fiber bundle than in an orthogonal direction. The axial diffusivity is the diffusivity along the principal axis - e.g., parallel to the direction of a fiber tract in white matter. The radial diffusivity is diffusivity in the plane orthogonal to the principal axis. The apparent diffusion coefficient is closely related to the mean diffusivity, which is the average diffusion of molecules across all directions.
Seorang pasien dengan trauma spinal cord thoracic akut menjalani dekompresi dan stabilisasi dengan instrumen. Modalitas imaging apakah yang terbaik untuk mengevaluasi lebih lanjut perkembangan dari trauma spinal cord ?
A. DTI MRI rostral terhadap injury B. DTI MRI pada lokasi injury C. CT myelogram D. MRI dengan gadolinium E. MRI fungsional pada lokasi injury
A. DTI MRI rostral terhadap injury
The correct answer is DTI MRI rostral to the injury. Several studies in animals and humans have shown that diffusion indices rostral to the site of injury provide useful metrics of cord injury. Some studies have shown correlations between DTI indices and histological evidence of recovery in animals, as well as functional recovery measures in humans. DTI MRI at the site of injury may be useful as well, but in a patient with instrumentation it will be extremely difficult to analyze due to hardware artifact. MRI with gadolinium does not provide as much information about evolving cord injury as DTI metrics. CT myelogram provides little information about cord integrity. Functional MRI has not been well studied in this application, and would also be difficult to interpret at the site of injury due to hardware artifact.
Perubahan yang telah diperkirakan apakah dalam fractional anisotropy (FA) dan radial diffusivity (RD) yang mengikuti trauma spinal cord akut ?
A. FA menurun, RD meningkat B. FA meningkat, RD menurun C. FA meningkat, RD meningkat D. FA menurun, RD menurun E. FA tetap, RD menurun
A. FA menurun, RD meningkat
The correct answer is FA decreased, RD increased. Following spinal cord injury, there is loss of integrity of the white matter tracts through the region of the injury. Therefore FA, which is typically elevated in an area of intact white matter tracts, decreases after injury. The RD increase is similarly thought to reflect the increased propensity of water to diffuse in a plane orthogonal to the direction of the injured white matter tracts.
Outcome apakah yang diperkirakan pada penurunan volume signifikan dalam kurun waktu 3 bulan setelah terapi untuk tumor metastasis dengan stereotactic radiosurgery (SRS) ?
A. Gejala neurologis meningkat B. Meningkatnya corticosteroid dependence C. Kontrol lokal pada 6-12 bulan D. Pseudoprogression E. Membaiknya survival keseluruhan
C. Kontrol lokal pada 6-12 bulan
Significant volume reduction 3 months after treatment of a metastatic lesion with stereotactic radiosurgery is predictive of local control 6-12 months after treatment. A recent report by Sharpton et al. suggested that metastatic lesions with a significant volumetric reduction measured on anatomic MR imaging at 6-12 weeks post SRS were highly likely to be lesions that ultimately showed excellent local control or response at later time points. This study is supported by Kim et al, who suggest that a very early volumetric response is associated with subsequent local lesion control. Early volumetric response has been shown to be associated with decreased corticosteroid dependence and decreased neurological symptoms. An early increase in volume in a lesion that ultimately went on to respond to SRS would be an example of pseudoprogression. Although local control was associated with early volumetric response, and subsequent variables that might impact patients’ quality of life were associated with early volumetric response, in these series early volumetric response was not found to be associated with overall survival. This may require larger powered studies, or it may be a factor associated with systemic disease control as opposed to intracranial disease control.
Berapakah penurunan volumetric median 6 bulan setelah SRS untuk metastasis otak ?
A. 75 % B. 50 % C. 25 % D. 100 % E. Tetap
A. 75 %
In a recent study by Sharpton et al., a volumetric response occurred by 6 weeks post-SRS with a median absolute volume reduction of 0.80 cm3 when compared to baseline; the median tumor volume reduction in decreased lesions at 6 weeks post-SRS was 75%. These results suggest that a robust, early volumetric response is associated with subsequent local control and parallels findings by Kim et al., who reported an association between a “good response,” defined as a decrease in total tumor volume by 75% at 4 weeks post-SRS, and local control. At 6 weeks post-SRS, a partial decrease in tumor volume was seen in 49/64 (77%) treated lesions. Of these 64 lesions, 16 (25%) were categorized as a complete response with no detectable residual tumor on imaging. The volumetric responses of breast, non-small cell lung cancer (NSCLC), melanoma, and renal cell carcinoma (RCC) metastases at 6 weeks, 12 weeks, and 6 months post-SRS were compared. Despite trends suggesting that melanoma and RCC metastases had less robust volume reduction than either NSLCLC or breast metastases, response categorization differences between these four primary types were not statistically significant.
Bagaimanakah waktu yang optimal untuk imaging setelah terapi untuk lesi metastasis dengan stereotactic radiosurgery (SRS) dalam rangka untuk menilai efektivitas dari terapi ?
A. 13-19 minggu B. 6-12 minggu C. 1-5 minggu D. 20-26 minggu E. 27-33 minggu
B. 6-12 minggu
The optimal time frame for imaging after treatment of a metastatic lesion with stereotactic radiosurgery is between 6 and 12 weeks after treatment in order to assess the efficacy of treatment. A recent study by Sharpton et al notes that measurable volumetric response occurred by 12 weeks following SRS in their series of 52 subjects with 100 metastatic brain tumors. Tumor response at 6-12 weeks was predictive of subsequent local control at 6 months and beyond. The authors suggest that consideration could be given to less frequent interval imaging for subjects who show local control at 3-6 months following SRS. This could save costs of repeated MR imaging studies, however, the potential for distal intracranial failure would may favor shorter interval between imaging studies.
Earlier imaging studies are not recommended or indicated as the standard of care for patients with brain metastases as pseudoprogression may lead to more imaging . Imaging timed with systemic disease or only obtained at the time of patient symptoms is likely to miss early progression or new disease and might preclude the efficacy of repeat radiosurgery or alternative interventions. The importance of shorter interval (q3-6 month MRI studies is supported by other series that note median time to progressions and distant intracranial failures as occurring at 5-7 months post SRS, respectively
Dengan memperhatikan terapi untuk complex unruptured paraclinoid aneurysms, modalitas tindakan apakah yang memiliki angka paling tinggi untuk terjadinya obliterasi aneurysma ?
A. Clipping
B. Pipeline endovascular device
C. Stent / coil
D. Bypass / trapping
D. Bypass / trapping
In a recently reported series of unruptured cavernous and paraclinoid aneurysms by Kim et al., the aneurysms treated with bypass had the highest obliteration rate. Obliteration rate for treatment with stent/coil was 83%, with Pipeline endovascular device was 83%, with clipping was 96%, and with bypass and trapping was 100%. The literature on bypass and trapping for paraclinoid aneurysms showed aneurysm occlusion rates of up to 100% with excellent clinical outcome achieved in 87% to 100% of the patients. This came with relatively low morbidity (5% to 10%) but a variable risk of mortality (0% to 5%).
Dalam menangani unruptured paraclinoid aneurysms, prosedur manakah yang memiliki angka paling tinggi untuk terjadinya stroke hemorrhagic pra dan post prosedur ?
A. Pipeline treatment B. Stent-assisted coil embolization C. Standalone coil embolization D. Microsurgical clipping E. Bypass and trapping
E. Bypass and trapping
Stroke rates were highest in the bypass-trapping group (20%) as reported in the study by Kim et al. The rates were 12% in the clipping group, 12% in the pipeline group, and 2% in the stent-assisted coiling group.
Efek samping apakah yang paling umum berkaitan dengan terapi pipeline untuk unruptured cavernous and paraclinoid aneurysms ?
A. Intraparenchymal hematoma B. Ischemic stroke C. Cranial nerve palsies D. GI hemorrhage secondary to antiplatelets E. Device deployment failure
C. Cranial nerve palsies
In a recent study by Kim et al., new cranial nerve palsies was the most common complication (13%) following pipeline treatment of unruptured cavernous and paraclinoid aneuryms. Two patients (8%) had small asymptomatic infarcts on MRI or CT discovered on follow-up imaging six weeks after treatment. One patient (4%) had a small, asymptomatic ipsilateral frontal lobe hemorrhage immediately post-procedure, but recovered without deficit. There were two cases of stent migration that required retreatment when discovered at routine six-week post treatment CT angiography. Two cases (8%) of intraprocedural incomplete device opening required follow-up balloon angioplasty to fully expand the device. One (4%) patient suffered a GI bleed related to prasugrel anticoagulation. In a previous series specifically studying paraclinoid aneurysms, flow diversion was associated with improved occlusion rates compared to other endovascular techniques. However, up to 9.3% of patients treated with PED suffer significant periprocedural complications (most often thromboembolic), which must be taken into consideration in the treatment algorithm.
