Pediatric Head and Neck Lesions: Assessment of Vascularity by MR Digital Subtraction AngiographyWeng Kong Chooi a , Neil Woodhouse a , Stuart C. Coley a  and Paul D. Griffiths a +Author Affiliations aFrom the Section of Academic Radiology, University of Sheffield, Royal Hallamshire Hospital, Sheffield, England .Address reprint requests to Paul D. Griffiths, Section of Academic Radiology, University of Sheffield, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2SB, England

Abstract

BACKGROUND AND PURPOSE: Pediatric head and neck lesions can be difficult to characterize on clinical grounds alone. We investigated the use of dynamic MR digital subtraction angiography as a noninvasive adjunct for the assessment of the vascularity of these abnormalities.METHODS: Twelve patients (age range, 2 days to 16 years) with known or suspected vascular abnormalities were studied. Routine MR imaging, time-of-flight MR angiography, and MR digital subtraction angiography were performed in all patients. The dynamic sequence was acquired in two planes at one frame per second by using a thick section (6–10 cm) selective radio-frequency spoiled fast gradient-echo sequence and an IV administered bolus of contrast material. The images were subtracted from a preliminary mask sequence and viewed as a video-inverted cine loop.RESULTS: In all cases, MR digital subtraction angiography was successfully performed. The technique showed the following: 1) slow flow lesions (two choroidal angiomas, eyelid hemangioma, and scalp venous malformation); 2) high flow lesions that were not always suspected by clinical examination alone (parotid hemangioma, scalp, occipital, and eyelid arteriovenous malformations plus a palatal teratoma); 3) a hypovascular tumor for which a biopsy could be safely performed (Burkitt lymphoma); and 4) a hypervascular tumor of the palate (cystic teratoma).CONCLUSION: Our early experience suggests that MR digital subtraction angiography can be reliably performed in children of all ages without complication. The technique provided a noninvasive assessment of the vascularity of each lesion that could not always have been predicted on the basis of clinical examination or routine MR imaging alone.

Pediatric head and neck abnormalities are relatively common and frequently are brought to medical attention because of their conspicuity and associated disfigurement. The nature of many of these lesions can be adequately assessed by clinical examination alone, but the vascularity of certain abnormalities is more difficult to evaluate and requires further investigation. MR imaging often is performed as the first imaging method to characterize the lesion and document the extent of the abnormality, sometimes as a prelude to treatment. One of the most important features that must be established is the vascularity of the lesion.

Vascular imaging can help to differentiate between high and low flow lesions in terms of structural changes, such as enlarged vessels and capillary staining, and can help to delineate hemodynamic parameters that are most simply assessed by the speed of arteriovenous shunting. Traditionally, this has been performed by transfemoral angiography, a technique that has a small but finite complication rate and can be difficult to perform in small children.

Recent advances in MR imaging have enabled the acquisition of dynamic (or time-resolved) angiographic data sets with high spatial and temporal resolution (1–3). These techniques have already been described for the assessment of brain arteriovenous malformations (4–9), dural fistulae (8–11), and

cerebrovascular disease (12, 13). We herein present our preliminary work with MR digital subtraction angiography in the assessment of the vascularity of pediatric head and neck lesions.

Methods

Twelve patients were studied (five male, seven female) with an age range of 2 days to 16 years. All examinations were performed on a 1.5-T system (Infinon; Philips Medical Systems, Cleveland, OH). Routine multiplanar imaging and time-of-flight MR angiography were performed before the dynamic acquisitions were obtained. MR digital subtraction angiography was performed in the frontal and lateral projections by using half of the total allowable dose of 1.0 mol/L gadolinium chelate (Gadovist; Schering AG, Berlin) for each projection. Contrast-enhanced T1-weighted spin-echo images were obtained after dynamic angiography was performed.

Our MR digital subtraction angiography protocol has previously been described in detail (4) and is summarized herein. The sequence uses a section-selective radio-frequency spoiled fast gradient-echo sequence (7/2 [TR/TE]; flip angle, 40°; matrix, 150 × 256; field of view, 230 mm; section thickness, 6–10 cm). Images were acquired as thick 2D sections every second for a total of 1 minute. After a preliminary unenhanced acquisition, a second run was performed during the IV administration of a bolus of contrast material (at 3 mL/s) and then a 10-mL saline flush at the same rate. The dataset was rapidly processed and viewed as a subtracted video-inverted cine loop with a temporal resolution of one frame per second.

Lesions were classified as high flow lesions if any of the following was shown: 1) rapid enhancement during the arterial phase of angiography, 2) arteriovenous shunting, or 3) enlarged vessels. Lesions that became conspicuous during the venous phase or did not show increased contrast enhancement were defined as low flow lesions.

Results

MR digital subtraction angiography was performed without clinical complication in all 12 patients. In each case, the images were considered to be of high quality, equal or better to the results we routinely achieve in the adult population. The salient clinical details and radiologic findings are summarized in the TableClinical details and MR imaging findings

Case No.

Sex, Age Clinical Details

Conventional MR Imaging Findings

MR-DSA Vascularity Final Diagnosis

1 (Fig. 1)

F, 3 yr*

Scalp mass, indeterminate vascularity

Enhancing soft tissue mass with flow void

High Extracranial AVM

2 (Fig. 2)

F, 14 mo

Neck swelling, indeterminate vascularity

Enhancing soft tissue mass with flow voids

High Hemangioma (proliferative phase)

3 (Fig. 3)

F, 1 wk

Large occipital mass, presumed occipital encephalocele

Enhancing heterogeneous extra-calvarial mass

High Undifferentiated highly vascular tumor (+)

4 F, 2 yr*

Eyelid mass, ?dermoid, ?encephalocele

Enhancing mass with flow voids

High AVM

Case No.

Sex, Age Clinical Details

Conventional MR Imaging Findings

MR-DSA Vascularity Final Diagnosis

5 M, 15 mo

Eyelid hemangioma Enhancing rounded eyelid mass, no flow voids

High AVM

6 (Fig. 4)

M, 5 yr*

Nasopharyngeal mass Heterogeneous mass with minor enhancement

Low Burkitt lymphoma (+)

7 F, 2 d*

Large palatal mass Large enhancing tumor High Cystic teratoma (+)

8 F, 16 yr

Sturge-Weber syndrome, ?ocular angioma

Choroidal thickening with enhancement

Low Diffuse choroidal angioma plus detachment

9 M, 2 yr*

Eyelid hemangioma Enhancing soft tissue mass, no flow voids

Low Hemangioma

10 F, 3 yr*

Scalp lesion Enhancing soft tissue mass, no flow voids

Low Venous malformation

11 M, 10 yr*

?VI naevus flammeus, ?Sturge-Weber syndrome

Choroidal thickening with enhancement

Low Diffuse choroidal angioma

12 M, 12 yr*

Known cervical osteochondroma

Displacement but no invasion of the vertebral artery by bony tumor

Low Osteochondroma with no vascular invasion (+)

Note.—DSA indicates digital subtraction angiography; F, female; M, male; AVM, arteriovenous malformation; (+), histologic confirmation; ?, possible.

* MR imaging examinations performed with the patient under general anesthesia.

Clinical details and MR imaging findings

In some instances, the initial clinical diagnosis was revised on the basis of MR imaging results. Figure 1 shows images obtained in a child with a suspected low flow vascular lesion of the scalp. Standard MR imaging showed an extra-calvarial mass with serpiginous flow voids indicative of enlarged vessels. MR digital subtraction angiography confirmed the high flow nature of this lesion. A 14-month-old child (Fig 2) presented with a large neck mass that could not be characterized by clinical examination. Conventional MR imaging showed appearances consistent with a large parotid hemangioma. MR digital subtraction angiography revealed high flow within this lesion by virtue of early arterial phase enhancement and also arteriovenous shunting. This was thought to be consistent with a hemangioma in the highly vascular (proliferative) phase. A 1-week-old neonate (Fig 3) presented with a huge occipital mass that was initially thought to be an encephalocele. MR digital subtraction angiography revealed a highly vascular amorphous mass, the vascularity of which was confirmed by histologic analysis. MR digital subtraction angiography was also able to show the absence of significant blood flow within a suspected tumor. Figure 4 shows images obtained in a 5-year-old male patient with a nasopharyngeal mass that was initially thought to be a juvenile angiofibroma on the basis of clinical findings. MR imaging and MR digital subtraction angiography revealed a large but relatively avascular mass. Biopsy was safely performed, and the lesion was shown to be a Burkitt lymphoma.

FIG 1.

Images from the case of a 3-year-old female patient with a suspected vascular abnormality of the scalp.

A, Unenhanced sagittal T1-weighted MR image shows an extra-calvarial soft tissue mass.B, Marked uniform enhancement can be seen after the administration of contrast material. Serpiginous flow void represents an enlarged feeding vessel.C, Selected MR digital subtraction angiograms show prominent filling of contrast material in the arterial phase and prominent enhancement of the lesion. This was considered to represent a high-flow lesion.

FIG 2.

Images from the case of a 14-month-old female patient with left-sided neck swelling.

A, Unenhanced axial T1-weighted MR image shows an encapsulated mass in the left parotid gland.B, After the administration of contrast material, marked contrast enhancement is seen. Note the vascular flow voids within the lesion.C, Selected MR digital subtraction angiograms show early arterial filling of the hypervascular lesion and arteriovenous shunting into an early draining vein. This is consistent with a parotid hemangioma in the proliferative phase.

FIG 3.

Images from the case of a 5-day-old female patient with a large occipital mass thought to be an encephalocele.

A, Sagittal T1-weighted MR image shows a large occipital mass with intermediate signal intensity.B, More heterogeneous appearance can be seen on the T2-weighted image. No intracranial communication is shown.C, Selected MR digital subtraction angiograms show rapid opacification of the lesion during the early arterial phase. Flow in this lesion was so high that the intracranial vessels are poorly shown. Pathologic examination revealed an undifferentiated highly vascular tumor.

FIG 4.

Images from the case of a 5-year-old male patient with a nasopharyngeal mass.

A, Lobulated nasopharyngeal mass is seen on the sagittal T2-weighted MR image.B, T1-weighted coronal MR image also shows the lobulated nasopharyngeal mass.C, Coronal contrast-enhanced fat-saturated T1-weighted MR image shows minor eccentric contrast enhancement.D, No significant contrast material flow was seen within the lesion on MR digital subtraction angiograms. This lesion was diagnosed as Burkitt lymphoma on the basis of biopsy findings.

In other cases, MR digital subtraction angiography provided complementary evidence of a low flow lesion. These included a suspected scalp venous malformation, a lid hemangioma, and choroidal angiomas in two patients with Sturge-Weber syndrome. One example of a shunting arteriovenous malformation did not show enlarged flow voids on the spin-echo sequences.

Discussion

Characterizing the vascularity of certain pediatric head and neck lesions may be difficult on the basis of clinical examination alone. It is, however, important to differentiate such abnormalities, because the differentiation will often influence the further management of these lesions (14, 15). High flow arteriovenous malformations are often treated by a combination of intra-arterial embolization and surgery (16). Percutaneous sclerotherapy is the preferred method of treatment for venous malformations (17). Hemangiomas usually do not warrant intervention, because many will spontaneously involute.Most head and neck tumors and vascular malformations show increased enhancement on standard MR images after administration of contrast material. Although certain appearances of high and low flow lesions, such as visible flow voids (18), have been depicted on standard MR images, these are static images that do not allow assessment of the hemodynamics of the lesion. Furthermore, flow voids may be absent or inconspicuous in certain lesions (19). The unique value of MR digital subtraction angiography is its ability to show the passage of a bolus of contrast material through the abnormality in a manner identical to that of conventional angiography.High flow lesions show rapid contrast enhancement during the early arterial phase and may show enlarged vessels and pathologic arteriovenous shunting with early venous filling. Low

flow lesions, such as venous malformations and certain hemangiomas, may show less dramatic contrast enhancement on routine MR images; however, most importantly, the lesion does not show early opacification on MR digital subtraction angiograms. Such lesions show either no vascularity on MR digital subtraction angiograms or appear during the venous phase (20).Ziyeh et al (20) recently reported their experience with time-resolved MR projection angiography in the assessment of head and neck vascular malformations. Using view-sharing and temporal interpolation, the authors were able to achieve a temporal resolution approaching four frames per second. Five patients with venous malformations showed no pathologic vasculature on dynamic images, whereas contrast enhancement was observed on T1-weighted spin-echo MR images. Two high flow arteriovenous malformations were readily identified and were classified as such by determining the time delay between the arrival of the contrast material bolus in the extracranial carotid circulation and the vascular malformation. Rapid arrival of contrast material was associated with intense enhancement on the dynamic sequences. Furthermore, our own early experience suggests that MR digital subtraction angiography may also allow assessment of the vascularity of neoplastic lesions without the risks and expense associated with conventional angiography.At present, MR digital subtraction angiography is inferior to conventional angiography in terms of spatial and temporal resolution and therefore has some limitation in the assessment of those arteriovenous malformations associated with rapid arteriovenous shunting. Although rapid sub-second MR imaging can be performed with frame rates similar to those of conventional angiography (21), such techniques remain experimental at this time and require further work to produce satisfactory spatial resolution. Furthermore, by using an IV injection of contrast material, there is simultaneous opacification of the internal carotid, external carotid, and vertebral circulations. This feature can create diagnostic difficulties with vessel superimposition and dural shunts. Current MR digital subtraction angiography techniques for use in the head and neck region also are limited to a small number of 2D projections that cannot be manipulated in the third plane and therefore cannot generate 3D models or be shown in an infinite number of oblique projections. A specific limitation of this study is lack of correlation with conventional angiography. Because the high flow arteriovenous malformations and parotid hemangioma were not considered for surgical intervention at this time, we could not justify subjecting these patients to further investigation.

Conclusion

Despite the limitations of this study and the technique it used, we think MR digital subtraction angiography has a potentially important role in the assessment of both neoplastic and non-neoplastic pediatric head and neck lesions.

Footnotes

Presented at the 41st Annual Meeting of the American Society of Neuroradiology, April 26–May 2, 2003; Washington, DC.

 

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Received July 16, 2003. Accepted after revision December 22, 2003. Copyright © American Society of Neuroradiology

Lesi Pada Kepala dan Leher Pada Pediatri : Penilaian Vaskularisasi dengan MR Digital Subtraction Angiography

Weng Kong Chooia, Neil Woodhousea, Stuart C. Coleya and Paul D. Griffithsa

+Author Affiliations

. aFrom the Section of Academic Radiology, University of Sheffield, Royal Hallamshire

Hospital, Sheffield, England

. Address reprint requests to Paul D. Griffiths, Section of Academic Radiology, University of

Sheffield, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2SB, England

 

Abstrak

TUJUAN : Lesi kepala dan leher pada anak bisa sulit untuk dikarakterisasi atas dasar klinis saja.

Kami menyelidiki penggunaan dynamic MR digital subtraction angiography sebagai tambahan

non-invasif untuk penilaian vaskularisasi kelainan ini.

METODE: Dua belas pasien (rentang usia, 2 hari sampai 16 tahun) dengan kelainan vaskular

yang diketahui atau diduga memiliki kelainan vaskular dipelajari. pencitraan MR Rutin, time-of-

flight MR angiography, dan MR digital subtraction angiography dilakukan pada semua pasien.

Urutan dinamis diakuisisi pada dua bidang di satu frame per detik dengan menggunakan bagian

tebal (6-10 cm) frekuensi radio manja cepat urutan gradien-gema selektif dan bahan kontras yang

diberikan secara bolus melalui IV. Gambar-gambar tersebut diambil dari urutan awal dan

dilihat sebagai lingkaran video terbalik

HASIL: Pada semua kasus, MR digital subtraction angiography berhasil dilakukan. Teknik ini

menunjukkan sebagai berikut: 1) lesi aliran lambat (dua angioma koroid, hemangioma kelopak

mata, dan malformasi vena kulit kepala), 2) lesi aliran tinggi yang tidak selalu dicurigai dengan

pemeriksaan klinis saja (hemangioma parotis, malformasi arteriovenous kulit kepala, oksipital,

dan kelopak mata ditambah teratoma palatal); 3) tumor hypovascular dimana biopsi bisa

dilakukan secara aman (limfoma Burkitt), dan 4) tumor hypervascular dari langit-langit

(teratoma kistik)

KESIMPULAN: Pengalaman awal merujuk pada bahwa MR digital subtraction angiography

dapat dilakukan pada anak-anak dari segala usia tanpa komplikasi. Teknik ini memberikan

penilaian noninvasif dari vaskularisasi setiap lesi yang tidak bisa selalu tdiprediksi berdasarkan

pemeriksaan klinis atau pencitraan rutin MR saja.

Kelainan kepala dan leher pada anak relatif umum dan sering dibawa ke perhatian medis karena

penonjolannya dan cacat terkait. Sifat banyak lesi ini cukup dapat dinilai dengan pemeriksaan

secara klinis saja, tetapi vaskularisasi kelainan tertentu lebih sulit untuk dievaluasi dan

memerlukan investigasi lebih lanjut. Pencitraan MR sering dilakukan sebagai metode

pencitraan pertama yang menggambarkan lesi dan mendokumentasikan tingkat kelainan,

kadang-kadang sebagai awal untuk pengobatan. Salah satu fitur yang paling penting yang

harus dicapai adalah vaskularisasi dari lesi. Pencitraan vaskuler dapat membantu untuk

membedakan antara lesi aliran tinggi dan rendah dalam hal perubahan struktural, seperti

pembuluh kapiler membesar dan pewarnaan kapiler, dan dapat membantu untuk

menggambarkan parameter hemodinamik yang paling sederhana dinilai oleh kecepatan

shunting arteriovenous. Secara tradisional, hal ini telah dilakukan dengan angiografi

transfemoral, suatu teknik yang memiliki tingkat komplikasi yang kecil tapi terbatas dan

bisa sulit untuk dilakukan pada anak-anak kecil.

Kemajuan terbaru dalam pencitraan MR telah memungkinkan akuisisi dinamis (atau waktu-

diselesaikan) set data angiografik dengan resolusi spasial dan temporal tinggi (1-3). Teknik-

teknik ini telah dijelaskan untuk penilaian malformasi arteri otak (4-9), fistula dural (8-11), dan

penyakit serebrovaskular (12, 13). Kami di sini menyajikan pekerjaan awal kami dengan MR

digital subtraction angiography dalam penilaian vaskularisasi lesi kepala dan leher pada pediatri

Metode

Dua belas pasien (rentang usia 2 hari sampai 16 tahun) dengan kelainan vaskuler yang diketahui

atau diduga dipelajari. Semua pemeriksaan dilakukan pada sistem 1,5-T (Infinon, Philips

Medical Systems, Cleveland, OH). Pencitraan multiplanar rutin dan time-of-flight MR

angiography dilakukan sebelum akuisisi dinamis diperoleh. MR digital subtraction angiography

dilakukan pada proyeksi frontal dan lateral dengan menggunakan setengah dari total dosis yang

diperbolehkan dari 1,0 mol / L gadolinium chelate (Gadovist, Schering AG, Berlin) untuk setiap

proyeksi. Gambar – gambar contrast-enhanced T1-weighted spin-echo diperoleh setelah

angiografi dinamis dilakukan

Protocol MR digital subtraction angiography kami sebelumnya telah dijelaskan secara rinci (4)

dan dirangkum di sini. Urutannya menggunakan sebuah section-selective radio frequency

spoiled fast gradient-echo sequence (7/2 [TR / TE]; sudut lain, 40 °, matriks, 150 × 256, bidang

pandang, 230 mm, ketebalan bagian, 6 - 10 cm). Gambar diperoleh setebal bagian 2D setiap

detik untuk total 1 menit. Setelah akuisisi awal tanpa penyengatan, percobaan kedua dilakukan

selama pemasukan kontras secara bolus melalui IV (pada 3 mL / s) dan kemudian siram garam

10 mL pada tingkat yang sama. Dataset dengan cepat diproses dan dipandang sebagai subtracted

video-inverted cine loop dengan resolusi temporal satu frame per detik.

Lesi diklasifikasikan sebagai lesi aliran tinggi jika salah satu dari berikut ini ditampilkan: 1)

penyengatan pesat selama fase arteri angiografi, 2) shunting arteriovenosa, atau 3) pembuluh

darah membesar. Lesi yang menjadi mencolok selama fase vena atau tidak menunjukkan

peningkatan penyengatan kontras didefinisikan sebagai lesi aliran rendah.

Hasil

MR digital subtraction angiography dilakukan tanpa komplikasi klinis pada semua 12 pasien.

Dalam setiap kasus, gambar dianggap berkualitas tinggi, sama atau lebih baik dengan hasil yang

kita capai secara rutin dalam populasi orang dewasa. rincian klinis yang menonjol secara detail

dan temuan radiologis diringkas dalam Tabel.

Dalam beberapa instansi, diagnosis klinis awal direvisi berdasarkan hasil pencitraan MR.

Gambar 1 menunjukkan gambar yang diperoleh pada anak dengan dugaan lesi vaskular kulit

kepala beraliran rendah. Standar pencitraan MR menunjukkan massa ekstra-calvarial dengan

serpiginous flow voids menunjukkan pembuluh membesar. MR digital subtraction angiography

mengkonfirmasi sifat aliran tinggi dari lesi ini.

Seorang anak berusia 14 bulan (Gambar 2) dengan massa besar pada leher yang tidak dapat

ditandai dengan pemeriksaan klinis. MRI konvensional menunjukkan penampilan yang konsisten

dengan hemangioma parotis besar. MR digital subtraction angiography menunjukkan aliran

tinggi dalam lesi ini berdasarkan peningkatan awal fase arteri dan juga shunting arteriovenous.

Hal ini dianggap konsisten dengan hemangioma dalam fase.sangat vaskular (proliferasi)

Seorang neonatus berusia 1 minggu (Gambar 3) dengan massa oksipital besar yang awalnya

diduga menjadi encephalocele. MR digital subtraction angiography menunjukkan massa amorf

sangat vaskuler, vaskularisasi yang dikonfirmasi dengan analisis histologis. MR digital

subtraction angiography juga mampu menunjukkan adanya aliran darah signifikan yang

menghilang dalam tumor yang dicurigai.

Gambar 4 menunjukkan gambar yang diperoleh pada pasien laki-laki 5 tahun dengan massa

nasofaring yang awalnya dianggap sebagai angiofibroma remaja berdasarkan temuan klinis. MRI

dan MR digital subtraction angiography menunjukkan massa yang besar tetapi relatif avaskular.

Biopsi aman dilakukan, dan lesi ini terbukti menjadi limfoma Burkitt.

Dalam kasus lain, MR digital subtraction angiography memberikan bukti pelengkap dari lesi

aliran rendah. Ini termasuk suspek malformasi vena kulit kepala, hemangioma kelopak mata, dan

angioma koroid pada dua pasien dengan sindrom Sturge-Weber. Salah satu contoh dari

arteriovenous malformation shunting tidak menunjukkan rongga aliran diperbesar pada urutan

spin-echo

Diskusi

Membedakan karakteristik vaskularisasi dari lesi kepala dan leher tertentu pada anak

mungkin sulit atas dasar pemeriksaan klinis saja. Hal ini, bagaimanapun, penting untuk

membedakan kelainan tersebut, karena diferensiasi sering akan mempengaruhi

manajemen lebih lanjut dari lesi ini (14, 15). Malformasi arteri-vena beraliran tinggi sering

ditindak dengan kombinasi embolisasi intra-arteri dan operasi (16). Sclerotherapy perkutan

adalah metode pengobatan yang disukai untuk kelainan vena (17). Hemangioma biasanya tidak

memerlukan intervensi, karena banyak yang akan berinvolusi secara spontan.

Kebanyakan tumor kepala dan leher dan malformasi vaskular menunjukkan peningkatan

penyengatan pada gambar MR standar setelah pemberian bahan kontras. Meskipun penampilan

tertentu lesi aliran tinggi dan rendah, seperti rongga aliran terlihat (18), telah digambarkan pada

gambar MR standar, ini adalah gambar statis yang tidak memungkinkan penilaian terhadap

hemodinamik dari lesi. Selanjutnya, void aliran mungkin tidak ada atau mencolok pada lesi

tertentu (19). Nilai unik MR digital subtraction angiography adalah kemampuannya untuk

menunjukkan berlalunya bolus bahan kontras melalui abormalitas yang identik dengan

angiografi konvensional. Lesi aliran tinggi menunjukkan penyengatan kontras yang cepat

selama fase arteri awal dan mungkin menunjukkan pembuluh membesar dan shunting

arteriovenous patologis dengan pengisian vena awal. Lesi aliran rendah, seperti

malformasi vena dan hemangioma tertentu, mungkin menunjukkan penyengatan kontras

kurang dramatis pada gambar MR rutin, namun, yang paling penting, lesi tidak

menunjukkan gambaran opaque awal pada MR digital subtraction angiogram. Lesi

tersebut menunjukkan baik tidak ada vaskularisasi pada MR digital subtraction

angiogram yang muncul selama fase vena (20).

Ziyeh et al (20) baru-baru ini melaporkan pengalaman mereka dengan time-resolved proyeksi

angiografi MR dalam penilaian malformasi vascular kepala dan leher. Menggunakan tampilan-

sharing dan interpolasi temporal, penulis mampu mencapai resolusi temporal mendekati empat

frame per detik. Lima pasien dengan malformasi vena tidak menunjukkan pembuluh darah

patologis pada gambar dinamis, sedangkan peningkatan kontras diamati pada gambar MR

yang T1-weighted spin-echo . Dua malformasi arteri-vena beraliran tinggi yang mudah

diidentifikasi dan diklasifikasikan seperti itu dengan menentukan waktu tunda antara

sampainya bolus bahan kontras dalam sirkulasi karotid ekstrakranial dan malformasi

vaskular. Kedatangan Cepat bahan kontras dikaitkan dengan peningkatan intens pada urutan

dinamis. Selain itu, pengalaman awal kita sendiri menunjukkan bahwa MR digital subtraction

angiography juga dapat memungkinkan penilaian terhadap vaskularisasi lesi neoplastik tanpa

risiko dan biaya yang terkait dengan angiografi konvensional

Saat ini, MR digital subtraction angiography lebih rendah daripada angiografi konvensional

dalam hal resolusi spasial dan temporal dan karena itu memiliki beberapa keterbatasan dalam

penilaian malformasi arteri-vena terkait dengan shunting arteriovenous cepat. Meskipun

pencitraan MR sub-detik yang cepat dapat dilakukan dengan frame rate yang sama dengan

angiografi konvensional (21), teknik tersebut tetap eksperimental saat ini dan memerlukan

pekerjaan lebih lanjut untuk menghasilkan resolusi spasial memuaskan. Selanjutnya, dengan

menggunakan suntikan IV bahan kontras, ada ke-opaque-an simultan karotis interna, karotid

eksternal, dan sirkulasi tulang belakang. Fitur ini dapat membuat kesulitan diagnostik dengan

superimposisi pembuluh darah dan shunt dura. Teknik MR digital subtraction angiography yang

ada sekarang untuk digunakan pada regio kepala dan leher terbatas pada sejumlah kecil proyeksi

2D yang tidak dapat dimanipulasi pada bidang ketiga dan karena itu tidak dapat menghasilkan

model 3D atau ditampilkan dalam jumlah tak terbatas proyeksi miring. Keterbatasan khusus dari

penelitian ini adalah kurangnya hubungan dengan angiografi konvensional. Karena malformasi

arteri aliran tinggi dan hemangioma parotis tidak dipertimbangkan untuk intervensi bedah saat

ini, kita tidak bisa membenarkan menggunakan pasien – pasien ini untuk penyelidikan lebih

lanjut.

Kesimpulan

Meskipun keterbatasan penelitian ini dan teknik yang digunakan, kita berpikir MR digital

subtraction angiography memiliki peran potensial penting dalam penilaian baik neoplastik dan

non-neoplastik lesi kepala dan leher pada anak - anak