Ivr mt

• Weakness


  • Costly additional hardware
  • High radiation dose
  • Does not allow lateral imaging
• Problems encountered

  1. Problem 1: Poor SNR - Increased quantum mottle

  2. Solution: Noise reduction algorithm - Iterative noise reduction algorithm

  3. Problem 2: Decreased residual tissue contrast

  4. Solution: Prefiltration of xrb - Use of a cxt w/ 4 PSP plates

  5. Problem 3: Misregistration

  6. Solution: Multi-stage registration (MSR)
• Hybrid subtraction


  Digital fluoroscopy that utilize the combination of temporal and energy subtraction
• Strengths of hybrid subtraction

  • Reduce ST motion artifact
  • More enhanced image contrast
• Weakness of hybrid subtraction

  • Long procedure
  • More expensive
  • Requisite increase in xray dose by 30-60%
• Problems encountered with hybrid subtraction

  1. Reduction of SNR about that half of temporal subtraction

  2. Misregistration
• Ways of problem correction for hybrid subtraction

  1. Reduced snr: Studies revealed that exposure dose per single image of hybrid was approx. 30% of conventional DSA. SNR is improved by increasing expo dose and application of post processing program

  2. Misregistration: Reregistration
• Intracranial angiography is for blood vessels of the brain

  
• Intracranial angiography introduced by Edgar Moniz


  1927

  
• Intracranial lesions


  • Aneurysm
  • AVM
  • Tumors
  • Artherosclerotic/stenotic lesions

  
• Great vessels in Intracranial angiography

  • R & L common carotid arteries (anterior circulation)
  • R & L vertebral arteries (posterior circulation)

  
• Branches of aortic arch

  • Innominate arteries/ brachiocephalic artery - bifurcates into R common carotid and R subclavian artery
  • L common carotid artery
  • L subclavian artery

  
• Carotid artery


  • Passes anteriorly along side the trachea and larynx at level of C4
  • External carotid: supplies blood to the extracranial and extraaxial circulation
  • Internal carotid artery: enters thru carotid foramen (temporal) then bifurcates into anterior and middle cerebral arteries

  
• Vertebral arteries


  • Ascend thru cervical transverse foramina – cranium (medial) – foramen magnum
  • Provides blood supply to cerebellum (posterior fossa)
  • Circle of willis : communicating arteries that connects the anterior and posterior cerebral arteries

  
• Technique for intracranial angiography

  1. Performed w/ trans femoral approach ; brachial/axillary approach possible

  2. Selective catheterization technique: allows the external and internal carotid to be examine sepa (direct)

  3. For atherosclerotic: extracranial carotid, subclavian, vertebral arteries) , injection of the aortic arch w/ imaging of the extracranial portions

  
• Circulation time and imaging program

  1. Egas moniz : transmit time of cerebral circulation – 3 secs (circulation is from: internal carotid artery – jug vein)

  2. Greitz : cerebral circulation – time b/w points of max concentration in carotid siphon and in parietal veins ; normal valve mean: 4.13secs

  3. Standard rad program: obtain subtraction mask and rapid seq images at 1 ½ to 3 images per second in AP AND LAT – during early/arterial phase (1 ½ - 2 ½ secs)

  4. After arterial phase: imaging are slowed to 1 image/sec for capillary / parenchymal phase & maintained at 1 img/s every other second for venous

  5. Entire program: 7-10 seconds

  6. Injection rates: 5-9mL/s for 1-2s

  
• Equipment for intracranial angiography

  • Rapid-sequence biplane imaging film/DSA couples w/ an automatic injector
  • Collimators
  • Lead cut-out diaphragms : frontal and lateral keyhole

  
• Patient preparation for intracranial angiography

  1. NPO before exam

  2. Adult pt: local anesthesia in conjuction w/ conscious sedation

  3. Explain

  
• Patient positioning for intracranial angiography

  1. Supine

  2. Support under points of strain : small of back, knees, ankle

  3. Wrist restrains and compression bands

  4. General anesthesia: for preventing patient movement
• Head positioning for intracranial angiography

  1. MSP – PERP – HEADREST - // to the laterally placed IR

  2. IOML – perp – horizontal plane (manual)

  3. AP and PA OBL proj: CR: caudally from the vertically placed IOML/ CR - // - floor of anterior fossa (line from supraorbital margin to a point ¾ inch (1.9cm) superior to EAM

  
• Aortic arch angiogram


  1. Visualize: artherosclerotic (partial) or occlusive (full) dse of extracranial carotid, vertebral and subclavian arteries

  2. Multiple side hole catheter posn in ascending aorta

  3. Simultaneous bi plane oblique projection

  4. PT posn: 35 deg RPO – MSP – perp – IR

  5. Chin of pt is raised, move shoulders inferiorly

  6. Crd: perp – 1 ¼ " (3 cm superior to sternal angle) – MP -IR

  7. Obj: RPO: opened aortic arch, carotid and vertebral arteries free from SI

  8. Add: rate of injection: 15-20 mL/s for total of 35-40 mL

  9. Representative imaging program: 2-3 img/s in ea plane for 4s

  10. Alternative imaging: 1 image in ea plane – pause 1s – inject cm – 2-3img/s for 3 sec

  
• Lateral projection of anterior circulation

  1. Pt posn: head -extended – ioml – perp – cr – msp - // - ir

  2. CRD: direct to a point slightly cranial to the outside & midway b/w forehead and occiput – ir

  3. Obj: demo A or carotid circulation

  4. Add: immobilization may be used
• AP axial projection (supraorbital) of anterior circulation


  1. Pt posn: msp – perp – midline of grid – head- ext – ioml – perp – ir

  2. Crd: 20 deg caudal (ap axial ) ; 20 deg cranial (pa axial) – line passing along ¾ : superior to and // w/ a line from supraorbital margin to a point ¾ " superior to EAM

  3. Obj: vessels above the floor of the A cranial fossa

  4. Add: immobilize head

  
• AP axial oblique (supraorbital) of anterior circulation

  1. Pt posn: head – rot 30 deg away from injection side

  2. If not, angle CR 30 deg toward injection side

  3. Crd: 20 deg caudal
• AP axial projection transorbital of anterior circulation

  1. PT POSN: Same w/ AP proj

  2. Crd: 20 deg cranial – midorbits – coinc w/ a line passing through center of orbit & a point ¼ " (1.9cm) superior to the auricle of the ear

  3. Rp : mid orbit
• AP axial oblique transorbital of anterior circulation

  1. PT: Head rot 30 deg away from injection side

  2. If not: cr 30 deg toward injected side

  3. CRD: 20 deg cranial – midorbits of the uppermost side

  4. Obj: internal carotid bifurcation and anterior communicating and middle cerebral arteries w/in orbital shadow

  5. Rp : midorbits
• AP axial projection of anterior circulation

  1. PT: Basic ap projn

  2. Crd: 30 deg caudal – 1 ½ " superior to glabella (for PA-cranial) – exits level of EAM
• AP axial oblique projection of anterior circulation

  1. PT: HEAD ROT 35-45 deg – away from injected side

  2. If not: angle cr – 35-45 toward injection side

  3. Crd: 30 caudal - 1 ½ " superior to glabella

  
• Lateral projection of posterior circulation


  1. PT: head ext – ioml – perp – horizontal – msp - // - plane ir

  2. Crd: horizontal – mastoid process at a point ¾ " superior to and ¾ " posterior to EAM

  3. Obj: demo posterior and vertebral circulation
• AP axial projection of posterior circulation


  1. PT: msp – perp – midline of grid – IOML in vertical

  2. Crd: 30-35 CAUDAL – 1 ½ " superior to glabella at level of EAM
• Submento-vertical projection


  1. Modified SMV for investigation of posterior circulation, anterior circulation (middle cranial fossa lesion)

  2. Not possible for elderly w/ cervical degenerative arthritis

  
• Pulmonary angiography is to R/O pulmonary embolic dse

  
• Guidelines for pulmonary angiography

  1. Catheter is passed through the peripheral vein – vena cava – R side of heart – pulmonary arteries

  2. Simultaneous AP and OBL proj in supine posn is reco ; SID for lat proj is 60" (152cm)

  3. Biplane porjn is not available ; use single plane 25-35 deg RAO and LAO or LPO and RPO posn

  4. CRD IS perp

  5. Compensating filter (trough) may be used for more unif density b/w lungs and verteb

  
• Procedure for pulmonary angiography

  1. Make the exposure

  2. Representative injection and imaging programs : 25mL/s for total of 50mL ; 2-4 img/s for 4s

  3. Followed by one per s for additional 4s in ea plane

  
• Thoracic angiography is to r/o aortic aneurysm, evaluate congenital or post surgical precedures, and for patients with aortic dissection

  
• Parts of the aorta

  • Ascending aorta
  • Arch of aorta
  • Thoracic aorta
  • Abdominal aorta

  
• Thoracic aorta


  • Lies close to vertebral bodies, 20cm(8") long
  • Begins at level of intervertebral disc b/w the

  
• Catheter passed through


  1. Peripheral vein

  2. Vena cava

  3. Right side of heart

  4. Pulmonary arteries

  
• Simultaneous AP and OBL projections


  • In supine position
  • SID for lateral projection is 60" (152cm)
• Biplane projection


  • Not available
  • Use single plane 25-35 deg RAO and LAO or LPO and RPO position