Книги по МРТ КТ на английском языке / Normal Findings in CT and MRI

217

MRI: Special Investigations

Cranial Vessels

The internal carotid arteries show normal course and caliber and are symmetrically disposed. Each carotid siphon is normal, showing no displacement or extrinsic compression. Intraluminal signal intensity is homogeneous.

The middle cerebral artery arises normally from the internal carotid on each side and forms normal insular loops. There is no circumscribed vascular narrowing or dilatation. The vessel lumen shows homogeneous signal intensity.

The anterior cerebral artery shows no signs of narrowing or displacement.

The basilar artery shows a normal course and caliber and divides into normal-size posterior cerebral arteries. The anterior and posterior communicating arteries on each side are normally developed and of normal size. No segments show convolution or circumscribed dilatation.

The other evaluable portions of the neurocranium show no abnormalities.

Interpretation

The cranial vascular system appears normal.

Checklist

Moeller, Normal Findings in CT and MRI © 2000 Thieme

All rights reserved. Usage subject to terms and conditions of license.

220 MRI: Special Investigations

Cranial Venous Vessels

MRI of the venous cranial vessels demonstrates a superior sagittal sinus of normal caliber with normal arrangement of draining superficial cerebral veins. The great cerebral vein and inferior sagittal sinus appear normal. The transverse sinus presents a normal caliber and usually shows slight asymmetry between the right and left sides. The other evaluable deep cerebral veins are normally developed and patent. No venous segments contain flow voids or filling defects.

The other evaluable portions of the neurocranium show no abnormalities.

Interpretation

The cranial venous vascular system appears normal.

Checklist

Supratentorial ! Superior sagittal sinus, superficial cerebral veins venous system (ascending cerebral veins), deep cerebral veins:

—Internal cerebral vein

—Great cerebral vein (of Galen)

—Straight sinus

—Superficial middle cerebral vein

—Sphenoparietal sinus

—Cavernous sinus

—Inferior petrosal sinus

!Sinus confluence

!Transverse sinuses (bilaterally symmetrical only in 20% of cases; 25% of cases have unilateral drainage, and more than 50% of cases show predominant right-sided drainage; bilateral asymmetry is normal, usually with a right-sided predominance)

!Sigmoid sinus

!Jugular bulb

Infratentorial ! Position (no displacement)

venous system ! Course (no excessive tortuosity, normal calibers, no general or circumscribed luminal dilatation)

!Signal characteristics (homogeneous intraluminal signal, no filling defect)

!Contours (smooth, no constrictions)

Moeller, Normal Findings in CT and MRI © 2000 Thieme

All rights reserved. Usage subject to terms and conditions of license.

MR Angiography of the Renal Arteries 223

MR Angiography of the Renal Arteries

The abdominal aorta displays normal course and caliber.

The renal arterial trunks are paired, arise at the proper level, and show normal distribution. The course, calibers, and contours of the renal vessels are normal, with no evidence of caliber irregularities.

The kidneys are paired and are normal in their position, shape, size, and borders.

Other imaged vessels show no abnormalities.

Interpretation

The renal arteries appear normal.

Checklist

Moeller, Normal Findings in CT and MRI © 2000 Thieme

All rights reserved. Usage subject to terms and conditions of license.

224MRI: Special Investigations

!Diameter (see below)

!No obstruction of urinary drainage

(if documented, ! Caliber (see below) e.g., inferior vena

cava and renal veins)

Important Data

1Abdominal aorta:

!Approximately 18−30 mm

2Aortic bifurcation:

!At approximately the L4-L5 level

3Origin of renal arteries:

!At approximately the L1-L2 level

4Renal artery:

!Diameter approximately 4−10 mm

5Position of superior poles of kidneys: a Right: superior border of L1

b Left: inferior border of T12 (right kidney is lower than left kidney by up to one vertebral body height)

6Distance between superior renal poles:

!Approximately 10 cm (4−16 cm)

7Distance between inferior renal poles:

!Approximately 13 cm (9−18.5 cm)

8Renal dimensions:

!Craniocaudal: 8−13 cm (<1.5 cm craniocaudal difference in renal sizes)

Renal cortical thickness: ! 4−5 mm

Time to corticomedullary equilibrium: ! 1 minute

Moeller, Normal Findings in CT and MRI © 2000 Thieme

All rights reserved. Usage subject to terms and conditions of license.