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BODY CT PROTOCOLS

Erik D. Weiss, M.D. M.P.H.

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STARTING POINTS

  • Not NPO. Just clear liquids (at least 4 hours).

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  • If Cr < 1.5 and GFR ≥ 60 mL/min/1.73 m^2, may proceed with IV contrast.
  • If Cr > 1.5 in a diabetic, > 2.0 in a non-diabetic, or GFR ≤ 30, default is no contrast, but can discuss with referring provider (also check to make sure patient is not on dialysis!)
  • If 30 ≤ GFR ≤ 60, can hydrate patient (75-100cc/hr NS or tell outpatients to drink water day before AND day after.
  • Use a lower osmolar agent - Visipaque

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UMC RULES

  • Must follow Cr and GFR levels obtained within the last 30 days

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  • Age < 50 with no risk factors: No serum Cr or GFR required
  • Age < 50 with one or more risk factors: Serum Cr and GFR required
  • Age > 50 with or without risk factors: serum Cr and GFR required

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UMC RULES

  • High risk: eGFR < 30
    • Avoid IV contrast
    • If required (ie. trauma, PE), will need to discuss with referring service
    • Prophylaxis
  • Intermediate risk: eGFR 30-45
    • Hydration: 250cc of 0.9% saline IV, no more than 3 hrs before and after contrast
  • Low risk: eGFR > 45
    • Give it

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  • Follow-up: If high or intermediate risk, obtain serum Cr and eGFR in 24-48hrs

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METFORMIN ISSUES

  • Predominant renal excretion
  • Contrast-induced nephropathy -> lactic acidosis

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  • Stop metformin for 2 days after contrasted CT. Recheck Cr before restarting.
  • If Cr > 1.5, do not give IV contrast. Will need to reschedule (or do noncontrast).

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CONTRAST ALLERGIES

  • History of severe reactions – no IV contrast.

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  • Mild reactions – steroid premedication:
    • Medrol 32mg PO @ 12 and 2 hours prior to scan
    • Benadryl 50mg PO with second dose of Medrol

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CENTRAL VENOUS CATHETERS

  • Only use a dialysis catheter as a last resort!
  • Will need to withdraw the heparin before administered contrast – nephrology must arrange all this.
  • Power rated (if not, needs to be hand injected).

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ORAL CONTRAST

  • Dilute barium or gastrograffin

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  • If suspect bowel perforation, do not give dilute barium
  • Don’t need oral contrast with bowel obstruction – air/fluid provides negative contrast

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  • No oral –
    • Acute bowel obstruction, renal stone
  • Water –
    • Pancreatic mass, CTA (renal, liver, aorta, adrenal/renal mass), CT urogram, HCC screening
  • Barium –
    • Routine cancer f/u, lymphoma, abscess, gyn mass/malignancy, acute pancreatitis
  • Gastrograffin –
    • Postoperative, perforation, ED cases needing positive oral contrast, non-acute SBO to assess bowel transit, acute appendicitis
  • Volumen
    • IBD, small bowel mass, GI bleed, malabsorption, CTA (mesenteric)

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RECTAL CONTRAST

  • Do not give if recent colonic/rectal surgery
  • May be given in suspected diverticulitis (not usually needed) if no peritoneal signs
  • Penetrating bowel injury
  • Preferably dilute gastrograffin or water
  • 200cc – rectosigmoid.
  • 900-1200cc – entire colon

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WHAT TO DO ABOUT UNOPACIFIED BOWEL LOOPS?

  • Decubitus/prone views
  • Inject through colostomy, ileal loops, pouches – with referring service
  • Reglan 10mg promotes gastric emptying, quickens bowel transit
  • Delayed imaging

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ROUTINE ABD/PEL

  • Portal venous phase: “SMART PREP” ROI over liver, 50 HU over baseline
  • Delayed scans through kidneys at 3 min

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  • Scans with IV and no oral contrast:
    • Appendicitis
    • Diverticulitis
    • Suspected acute GI bleed, bowel ischemia, bowel obstruction, perforation

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TRAUMA

  • Water
  • IV
  • If renal or bladder injury suspected, make sure collecting system/bladder are opacified. May need to repeat at 10min delay
  • If penetrating injury, possible colonic injury, rectal contrast
  • If pelvic fractures, scan entire abdomen and pelvis on delays to assess for extravasation

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METASTATIC DISEASE

  • Routine abdomen/pelvis

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  • Add arterial phase liver if:
    • Neuroendocrine tumor
    • Carcinoid
    • RCC
    • Melanoma
    • Sarcoma
    • Thyroid cancer
    • Choriocarcinoma
    • Pheochromocytoma

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GI BLEED

  • Volumen
  • Noncontrast phase
  • Arterial – SMART PREP aorta 150 HU
  • Portal venous – 70sec
  • Delayed – 3min

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RETROPERITONEAL HEMORRHAGE

  • No oral contrast
  • If spontaneous hemorrhage due to anticoagulation, no IV contrast.
  • IV contrast for vascular extravasation due to recent intervention or trauma
  • If extravasation seen on initial scan, may do delayed phase

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CT CYSTOGRAM

  • Passive filling of bladder by IV contrast is not sufficient to exclude bladder rupture
  • 200-300cc dilute contrast (Cystopaque) into bladder via Foley (make sure urology/trauma has cleared possible urethral injury first)
  • Post-void images not necessary

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TRIPLE PHASE LIVER - HCC

  • Surveillance or follow-up after chemoembolization (primary or metastatic), liver transplant

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  • Water
  • Noncontrast liver
  • Arterial phase liver - ~30sec, 170 HU over baseline aorta (minimal contrast in PV)
  • Portal venous – 70sec
  • Delayed phase – 4min

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CHOLANGIOCARCINOMA

  • Water
  • Noncontrast
  • Noncontrast liver
  • Arterial phase liver - 170 HU over baseline aorta (minimal contrast in PV)
  • Portal venous – 70sec
  • Delayed phase – 10min

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ADRENAL MASS

  • No oral
  • Noncontrast – then radiologist checks
  • Portal venous phase – 80sec
  • Delay – 15min

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RENAL MASS

  • Water

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  • Noncontrast
  • Corticomedullary phase – 30sec
  • Nephrographic phase – 180sec

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RENAL INFECTION/STONE

  • Acute pyelonephritis – routine abdomen with delayed phase at 4-5min

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  • Renal abscess – same as renal mass.

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  • Urolithiasis – no oral, no IV, bladder shouldn’t be empty
    • If find stone at UVJ, do prone

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RENAL ARTERY STENOSIS

  • No oral
  • Arterial – SMART PREP over aorta with threshold 100 HU

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RENAL DONOR

  • Water
  • Noncontrast phase – reviewed, if see hydro, may have to scan rest of abdomen/pelvis to find stone
  • Arterial – SMART PREP over aorta, 100 HU
  • Venous – 20sec after arterial phase
  • Delay – 4min

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CT UROGRAM

  • Moderate bladder distention, don’t go to bathroom, clamp Foley
  • No oral, patient should be well hydrated

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  • Noncontrast
  • Nephrographic phase – 80sec
  • Delay – 8min (may have to repeat, standing, prone)
  • If obstruction, may have to increase delay time

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PANCREATIC MASS

  • Acute pancreatitis should be done as routine abdomen (add noncontrast phase if suspect hemorrhage), water

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  • Water
  • Opacification/distention of duodenum is helpful
  • Noncontrast
  • Arterial – 35sec
  • Portal venous – 80sec
  • Delay – 3min

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CT ENTEROGRAPHY

  • Crohn’s dz, other IBD

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  • Portal venous phases – 60 sec, 80sec

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  • Volumen (should be fasting 6hr prior to scan)

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AORTIC DISSECTION

  • No oral
  • Noncontrast
  • Arterial – SMART PREP over aortic arch, 100 HU
  • Portal venous phase

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AORTIC ANEURYSM

  • No oral
  • Noncontrast
  • Arterial – SMART PREP over aorta, 100 HU

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  • If post-stenting, do delay at 3min

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NEW CHEST CT

  • Lung nodule seen on CXR or CT neck
  • New lung carcinoma
  • Mediastinal mass, pleural disease, mesothelioma, LAD

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  • Noncontrast
  • Arterial phase (30sec)

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FOLLOW-UP CHEST CT

  • Follow-up lung nodule (from prior CT)
  • Follow-up lung carcinoma
  • Mediastinal mass, pleural disease, mesothelioma, LAD

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  • Noncontrast only

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PE PROTOCOL CT

  • Arterial phase (30sec delay)
  • SMART PREP main pulmonary artery (100 HU)

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HI-RESOLUTION CHEST CT

  • ILD, pulmonary fibrosis
  • Chronic cough, bronchiectasis, asthma, sarcoidosis, pneumoconiosis, hypersensitivity pneumonitis, BOOP, scleroderma, SLE, RA, drug/amiodarone toxicity, reticulonodular lung disease

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  • Noncontrast
  • Inspiration, expiration
  • Prone, supine
  • Routine helical chest without contrast

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