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CURRENT PATHOLOGY IMAGING GUIDELINES

CONTENTS

A. Neck and thorax

B. Upper abdomen

C. Genitourinary system

D. Vascular system

Imaging resources

Problem management

  1. deep venous thrombosis
  2. arterial obstruction
  3. arterial ischemia
  4. aneurysm of the abdominal aorta
  5. dilatation of a peripheral artery
  6. lower extremities edema
  7. abdominal vessels
  8. gastrointestinal and posttraumatic haemorrhage

E. Central nervous system

F. Spine

G. Extremities

H. Nuclear Medicine

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IMAGING RESOURCES

[Plain film:]

  • vascular calcifications (aneurysm of the aorta, arteriosclerosis, diabetic angiopathy), complications (atrophy, infections)

Arteriography

  • preoperative work-up (detailed anatomy, collaterals)
  • allows consecutive interventional procedures (dilatation, embolisation).

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Pulmonary Angiography

  • pulmonary embolism (only if at least one positive previous test such as Doppler, scintigraphy, D-dimers)
  • arteriovenous malformations, mycotic aneurysm
  • contraindications: cardiovascular instability, ventricular arrhythmia, left bundle-branch block, severe pulmonary hypertension, allergy to contrast media, myeloma, unstable diabetes, renal failure.

Digital substraction intravenous angiography:

  • no arterial puncture, easier to perform
  • less anatomical detail, unforeseeable picture quality, necessity of high volumes of contrast medium.

Phlebography

  • imaging of recent and older thromboses if Doppler ultrasound unconclusive. May fail to opacify some deep veins.
  • preoperative work-up: integrity of the deep venous network, good depiction of the perforating and varicose veins.

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EchoDoppler ultrasound

  • morphological analysis of the vessel (arteries: stenosis, atheroma, dilatation, thrombus / veins: compressibility of the vessel, dilatation, thrombus)
  • Color Doppler visualization of the flux in real time (stenoses, accelerations and decelerations, demonstration of pseudo-/aneurysms and of arteriovenous fistulas)
  • Power Color Doppler ("energy", "angiographic") : the signal is not depending on the angle of ultrasound incidence, whence better visualization of the vascular tree of an organ or of a vessel in a horizontal plane.
  • Pulsed spectral Doppler: direction and speed of the flow, haemodynamic profile of a stenosis, of intraparenchymatous vessels
  • Continuous spectral Doppler: more sensitive to slow flow than pulsed Doppler, but doesn't show direction of the flow, doesn't explore a definite volume, no ultrasound images
  • Doppler ultrasound after intravenous contrast medium: higher vascular Doppler signal in difficult cases; easier parenchymal lesion depiction with cinetic study possibility.

CT angiography

  • isometric acquisition with 3D volumic reconstruction (renal arteries, coeliomesenteric vessels, polygon of Willis, carotids)
  • highly calcified vessels are more difficult to image

MR angiography

  • several complementary techniques, 2D and 3D. Artery calcifications don't influence image quality
  • no X-rays, no iodinated contrast medium (often IV Gadolinium)
  • adequate patient collaboration necessary
  • spatial resolution is a little lower than with angioCT
  • artifacts may sometimes cause under- or overestimation of a stenosis. May miss very small intracranial aneurysms.

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PROBLEM MANAGEMENT

1. Deep venous thrombosis

  • EchoDoppler: DVT, ruptured popliteal cyst, abscess or hematoma of the calf, panniculitis, fasciitis, aneurysm or thrombosis of the popliteal artery. Allows to rule out a thrombosis from the iliofemoral to the popliteal level. Thrombosis of calf veins, superficial thrombophlebitis
  • CT angiography or phlebography if Doppler inconclusive
  • D-dimers sampling (very sentitive but not specific)
  • Plethysmography

2. Arterial acute obstruction

  • Arteriography (vital organ or threat of necrosis): preoperative work-up; allows interventional procedures or a local fibrinolysis
  • EchoDoppler in most other cases
  • CT angiography, MR angiography.

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3. Arterial ischemia

  • EchoDoppler: visualization and measurement of stenoses, atheroma plaque, aneurysms, steal syndrome (subclavian), reversal of flow. Applications: carotids, extremities, abdominal vessels, cerebral arteries (transcranial, transfontanellar Doppler)
  • MR angiography: more precise work-up
  • Angio-CT: same as MRI, but lower sensitivity for carotid or vertebral artery dissection
  • Arteriography: to perform angioplasty, as preoperative work-up or for traumatic lesions.

4. Aneurysm of the abdominal aorta

  • EchoDoppler: allows to rule out an aneurysm. Demonstrates the dilatation, the wall thrombus, the remaining aperture; less reliable than CT to rule out fissuration of the wall. Fairly high risk of rupture if diameter > 5 cm.
  • CT (and angio-CT): more precise diagnosis (inclusion of the renal arteries in the aneurysm, abdominal organ ischemia, signs of fissuration).
  • MR angiography
  • Arteriography: preoperative work-up

5. Dilatation of a peripheral artery:

  • Color and pulsed EchoDoppler: aneurysm, ectasia, arteriovenous fistula. Haemodynamic downstream repercussion. Compression treatment of an iatrogenic pseudoaneurysm (after arterial catheterism).
  • MR or CT angiography
  • Arteriography: preoperative work-up, stent placement.

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6. Lower extremities edema:

  • EchoDoppler: abdominal masses compressing the iliac or caval veins. Thrombosis. Cardiogenic central venous stasis. Ascitis.
  • CT: complementary to echography
  • MRI: tumoral thrombus extension
  • Cavography: usually performed at the time of caval filter placement.

7. Abdominal vessels:

  • EchoDoppler: portal hypertension (aspect of the liver, spleen, ascitis, collaterals, flow inversion of portal, superior mesenteric & splenic veins, portal thrombosis, portocaval shunt follow-up); Budd-Chiari, thrombosis of a renal vein, mesenteric artery stenosis, arcuate ligament compression, arterial thrombosis (mesenteric infarct), systemic hypertension (see renovasular hypertension).
  • CT (if necessary, angio-CT, MR angiography): problem solving
  • Arteriography, portography: problem solving + preoperative workup; interventional radiology (dilatation, stents, embolisation, shunts).

8. Gastrointestinal and posttraumatic haemorrhage:

  • CT, Arteriography: aneurysm, gastroduonenal ulcer, diverticulum, Meckel, arteriovenous malformation, angiodysplasia, tumor. Extravasation visible only if active bleeding > 0.5 ml/min. Selective embolisation possible.
  • Scintigraphy: search of Meckel, locates bleeding source if oozing > 0.5 - 0.05 ml/min.
  • If subacute, digestive examinations: endoscopy, videocapsule endoscopy, CT colonography, barium enema/meal (not to be done before angiography), enteroCT.
  • EchoDoppler, CT: portal hypertension staging (oesophagial varices).

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Pierre Bénédict, MD, FMH radiologist, Lausanne, 1997-2018

References:

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