CTPA 2009 Vassilios Raptopoulos, MD Longwood Non-invasive Cardiac Imaging Seminar Beth Israel...

CTPA 2009Vassilios Raptopoulos, MD

Longwood Non-invasiveCardiac Imaging Seminar

Beth Israel Beth Israel HarvardHarvardDeaconessDeaconess Medical MedicalMedical CenterMedical Center School School

December 14, 2009

CTPA 2009

•64-MDCT•Utilization•I+ delivery•Dual Energy•PE severity•Radiation•MRI - Gad•Venography•Triple R/O

CTPA 2009

•Utilization•Technique•DVT•Radiation•In Pregnancy•Large •Small PE•Chronic PE•Triple R/O

Utilization

MDCT for PE “a technological marvel”

• “revolutionized our diagnostic approach”– non-invasive, fast, comfortable, < mm

resolution in < 10sec (4 sec w 64 MDCT)• Massive embolism (surgical planning)

6th order thrombi (? clinical significance)• Lung & chest wall - CT venography• Prognosis

– RV enlargement - Thrombus burden

Goldhaber SZ. (from BWH) N Engl JMed Apr 28 2005; 352:1812 (Editorial)

Guidelines for Management Suspected PEBritish Thoracic Society

• D-Dimer– Not in high clinical probability

– A negative test reliably excludes PE

• Imaging– CTPA the recommended initial imaging modality

• A good quality -CTPA does not require additional tests

– Negative isotope scan reliably excludes PE

– Single normal leg US is not reliable to exclude sub-clinical PE

Thorax 2003;58:470

Management of suspected Acute PE in the era of CTA A Statement from the Fleischner Society

“multidetector CT angiography has fulfilled the conditions to replace pulmonary angiography as the reference standard for diagnosis of acute PE.”

Remy-Jardin M et al Radiology (Nov) 2007;245: 315-329

http://www.fleischner.org/

Why CT?

Patel & Kazerooni, AJR 2005;185:135

Author Year # Pts

κ

CT NM Ang

Mayo 1997 142 0.85 0.61

Grenier 1998 139 0.85 0.61

Heroki 1999 758 0.71 0.40

Blachere 2000 179 0.72 0.22

Coche 2003 94 0.94 0.94 0.66

Interobserver agreement

© 2009 Lippincott Williams & Wilkins, Inc. Published by Lippincott Williams & Wilkins, Inc. 3

Interobserver Agreement Between On-Call Radiology Residents & Radiology Specialists in the Diagnosis of PE

Verweij, J et alJournal of Computer Assisted Tomography. 33(6):952-955, November/December 2009(VU University, Amsterdam)

TABLE 1 . Interpretation of Discordant Cases

114 studies 37 PE 8 discordant93% agreement = 0.84

For PE: Sens 92%, Spec 99%

Discordance between CT and Angiography in the PIOPED II Study• Discordance in 20 of 226 CTA & cath results

• 40 hr interval: thrombi can remain the same, resolve, develop, or result from angio

Wittram C. et al (MGH & Wisc) Radiology (Sep)2007;244:883-889.

VARIABLE Points

Clinical DVT 3

No alternative Dx 3

HR > 100 bpm 1.5

Imobil/Surg 4 wks 1.5

Previous DVT/PE 1.5

Hemoptysis 1

Cancer 1

CLINICAL PROBABILITY

points

Low < 2

Intermediate 2-6

High > 6

Wells PS al Thromb Haemost 2000;83:416-420

Predicting probability of PE Diagnostic Approach

Predicting probability of PE

CLINICAL PROBABILITY

points

Low < 2

Intermediate 2-6

High > 6

Fedullo & Tapson. NEJM 2003;349:1247 (UCSD)

Recommendation

• D-Dimer

• CTPAif equivocal VQ & US

Tapson V. N Engl J Med 2008;358:1037-1052

Diagnostic Approach to Suspected Acute Pulmonary Embolism

2008

D-Dimer in high-risk oncology pts in urgent setting

King V et al (Memorial Sloan-Kettering ) Radiology (Jun) 2008;247:854-861

92% FP3% FN

CTA in the evaluation of acute PE

• 575 CTPAs– PE: in 9.57%

• D-dimer: 224 (39%)– CTPA in 146 w nl or

intermediate

• Suboptimal use of Wells criteria

• Overuse of CTA (screening rather than dx exam)

Costantino MM (Oregon U) AJR (Aug) 2008; 191:471-474

15% 7%

Copyright © 2009 by the American Roentgen Ray Society

Corwin, M. T. et al. AJR 2009 May;192:1319-1323 (Brown U)

Use of D-Dimer to Determine Need for CT

Alternative Diagnosis

• In 130 of 512 patients (25.4%) PE was excluded and an alternative diagnosis considered likely

• Unique advantage of CTPA in comparison with other diagnostic tests for PE

Van Stijen et al J Thromb Haemost 2005 Nov; 3:2449

pneumonia 67

malignancy 22

pleural fluid 10

cardiac failure 10

COPD 6

other 15


Kritsaneepaiboon, S. et al. Am. J. Roentgenol. 2009 May;192:1246-1252 (Boston’s Chilren’s Hospital)

12-year-old girl with shortness of breath for 10 days

13 of 84 children5 – catheters4 – malignancy2 – vascular malf.

CTPA in Children


Lee, E. Y. et al. Am. J. Roentgenol. 2009 Sep ;193:888-894 (Boston’s Children’s)

--Bar graph shows frequency and types of alternative diagnoses identified in children

with clinically suspected but excluded pulmonary embolism (n = 96)

CTPA in Children – Alternative Dx

Increased use of CTPA

• Pennsylvania: from 1997 to 2001

• Mean 0.004% in CTPA per year

use associated with lower severity of illness and lower mortality(from 13% to 10%)

20.4

30.627.4

38.6

0

5

10

15

2025

30

35

40

PE/100,000 CTs/100 pts

incidence of PE & use of CT in hospitalized patients

1997 2001

DeMonaco NA et al (Pittsburgh) Am J Med (Jul) 2008;121:611-7

Role of CT & NM in Work up of PE

3.5 0.6

3.8 0.7

3.4 0.6

2.8 0.3

3.8 0.7

3 0.3

3.9 0.8

0 1 2 3 4 5

All

Academic

Non_Acad

Rural

Urban

Small

Large

% of pts w/ symptoms having tests in 2005 (n= 3.270)

CT

NM

Bhargavan M et al (Johns Hopkins) AJR (Nov) 2009;193:1324-32

Technique

MDCT Pulmonary Angiography

Technique at BIDMC

• 80 - 100 mL at 4 mL/sec– (Scan duration + 3) x Inj. Rate

• Trigger at LA (100 HU)

• Shallow inspiration

• 1/2 sec rotation

• 120 kVp (?80)

• Variable mA (NI ~16)

• Scan acquire: 0.5 mm

• Scan display: 2.5 – 5 mm

• Axial, Coronal & Sagittal

Optimal timing window

Lee CH et al, AJR Feb 2007;188:313 (Seoul National U)

SVC PA Ao

CTPA

CP

Deep inspiration Shallow inspiration

Chest pain: Ao & PA

Iodine delivery rate

Keil S et al. (Aachen U) Eur Radiol (Aug) 2008;18:1619-5:

A: 148 ml300 mgI/ml @ 4.9 ml/sB: 120 ml:370 mgI/ml @ 4.0 ml/s

Iodine delivery rate:1.47 vs. 1.48 gI/s

Adjust injection rate

I+ consentration & speed of injection Proportional to vessel enhancement

Alternative IV contrast: Gadolinium

Remy-Jardin M et al. Radiology 2006; 238:1022

0.3-0.4 mmol/kg at 6 ml/sec – 15 ml saline flush80-100 kVp

CAD in PE: Influence on radiologists performance

0

20

40

60

80

100

R1 R2 R3

33 pts w 215 thrombi

Rad R+CAD

Das M et al (U Aachen) Eur Radiol (Jul) 2008; 18:1350-5

PE Detection w/ Dual Energy CT

Zhang L et al. Radiology 2009 Jul;252:61-70 (Nanjing U, China)

©2009 by Radiological Society of North America

PE Detection w/ Dual Energy CT

Zhang L et al. Radiology 2009 Jul;252:61-70 (Nanjing U, China)


CTPA w/ dual-energy & Blood flow merge

Images show a true-positive case of PE in rabbit


Thieme, S. F. et al. Am. J. Roentgenol. 2009 Jul;193:144-9 (Ludwig Maximilian U, Munich)

Dual Energy CT for Iodine distribution

--41-year-old woman with pulmonary embolism

Occlussive thrombus

Thromboembolic Disease - DVT

Indirect CT Venography

Sens & Spec CTA 86% & 96% +Ven 90% & 95%

Stein et al NEJM 2006;354:2317

CTA + Venography Dx VTE by 27%

Ghaye et al Radiology 2006;249:256

Minimal benefit from venography

Johnson et al Emerg Radiol 2006;12:160

Perrier A, Roy P-M, Sanchez O et al. NEJM 2005; 321:1760-8. (Geneva University)

Routine indirect CT Venography in patients undergoing CTPA• Pts: 446 high risk - 383 low risk

– malignancy, h/o VTE & CV, post surgery

• Incremental value of CTV: 3.4%– 0.72% in low-risk & 2.6% in high-risk

• CTV may only be useful in patients with a high probability for PE

Andetta R et al (BWH) AJR (Feb) 2008; 190: 322 - 326

Indirect CT Venography. Include the pelvis?• no difference in the

detection of VTE whether or not the pelvis is included

• 2074 pts:

• 383 VTE– (237 PEs + 46 DVT only)

• Isolated pelvic DVT: 2

Kalva SP et al. (MGH): Radiology (Feb) 2008;246:605-611

CTV and US are diagnostically equivalent: data from PIOPED II

Goodman LR et al AJR (Nov) 2007; 189:1071-1076

Parameter US pos (%) US neg (%) Total

CTV pos 81 (11) 17 (2) 98

CTV neg 15 (2) 598 (84) 613

Total 96 615 711

CT Venography 2009 – 64 MDCT

50

3

914

0

10

20

30

40

50

PE- PE+

DVT and PE (n = 306)

DVT-

DVT+

Nazaroglou,H AJR (Mar) 2009; 192:654-661

CT Venography 2009 – Selective Use

• High risk patients – Signs of DVT or previous DVT

• Severely ill or ICU patients– Increased suboptimal studies

• Recent surgery in pelvis

• Cast or extremity surgery

• Can not do US

Goodman LR AJR (Feb) 2009; 250:327-330

Radiation& Image Quality

Brenner D and Hall E. N Engl J Med 2007;357:2277-2284

Estimated Number of CT Scans Performed Annually in the United States

CT

• 1991-96: ~ 0.4% of all cancers in the US

• Adjusting for current use: 1.5 to 2.0%

Estimated cancersfrom CT

mA: Reduced dose CTPA

MacKenzie JD et al. AJR (Dec) 2007; 189:1371 (BWH)

Effect of mAs(38 pts wlow mod clot burden)

best worst

kVp: image quality and radiation at CTPA with 100- or 120-kVp

• Prospective, randomized study

• 2 groups of 30 pts• 200 mA• 80 mL IV contrast

• Effective dose:

1.37 vs 2.44 mSv (↓ 44%)

Heyer CM et al. (U Bochum, Germany) Radiology (Nov) 2007;245:577

• 126 pts: 100 kVp, ATMC, 80 ml

• Age and weight: YES

• Sex and peripheral catheters: NO

Roggenland D et al (Ruhr-University of Bochum, Germany) AJR (Jun) 2008; 190:W351-W359

Impact on Vessels & Image Quality

80 vs 120 kVp

Characteristics 120 kVp 89 kVp P

Main PA HU 309 376 < 0.001

Noise in HU 19 25 <0.001

Image quality 3.8 3.9 NS

n = 400 scans energy attenuation because high atomic # of I and K-edge

Matuoka S et al AJR 2009 Jun; 192:1651-6 (BWH, Harvard U)


Hurwitz, L. M. et al. Am. J. Roentgenol. 2009 Jan;192:244-253 (Duke U)

Bismuth Breast shields

chest phantom (n1 Lungman, Kyoto Kagaku Company)

May dose to breast by 30%

CTPA in Pregnancy

CTPA vs Sintigraphy in Pregnancy

36

42

0

5

10

15

20

25

30

35

40

CT Pregn NM Pregn CT Non-Pregn

% of inadequate studies

Ridge CA et al AJR 2009 Nov;193:1223-7 ( St Vincent U, Dublin)

N = 28 pregnancy CTPAs

CTPA: vascular enhancement in pregnancy

Andreou AK et al (Norfolk & Norwich U) Eur Radiol 2008; 18:2716-22

16 pregnant and non- pregnant pts120 kVp 80-400 auto mA20 sec delay

PA: 260 HU vs 372 HU (p<0.001)

KVP Pregnancy CTPA at BIDMC

• No C-

• 100 mL at 4 mL/sec

• Delay: 15 sec

• 100 kVp

• 200 mA

Litmanovich et al. JCAT (in press)

© 2009 Lippincott Williams & Wilkins, Inc. Published by Lippincott Williams & Wilkins, Inc. 9

Dose Reduction in Pregnancy

Litmanovich, Diana et al BIDMC JCAT 33(6):961-966, November/December 2009. (BIDMC, Harvard)

FIGURE 2 . Per-patient distribution of DLP values in both the control and the pregnancy groups. Individual DLPs demonstrate substantial difference between the 2 groups, with substantially higher DLPs seen in the control group compared with the pregnancy group.

Effective Dose (mean)105 mGy-cm 576 mGy-cm 1.8 mSv 9.8 mSv

Pregnancy CTPA

270

280

290

300

310

320

330

PA LLL Ao

Pregnant Contols

Litmanovitch et al: JCAT 33(6):961-966, November/December 2009 (BIDMC, Harvard)

Vessel Attenuation Signal to noise

Pregnancy CTPA – Fetal shielding

• Phantom experiment• 30% barium

Yousefzadeh HT et al. (U Chicago)

Radiology 2006; 239:751

• Pair of lead aprons

Ibal GR et al (Leeds) Br J Radiol (Jun) 2008;81:499-503

Guidelines for CT & MRI use in pregnancy (UCSF)

• Appendicitis: US (if neg consider MRI or CT) • PE: CT *• Renal colic: US • Trauma: US &/or CT (if serious injury is suspected)• Low-dose CT pelvimetry • Iodinated contrast seems safe – iv gadolinium is

contraindicated (only when absolutely essential) • Continue breast-feeding immediately after I or gad• Teratogenesis is not a major concern • Carcinogenesis is a potential risk

Chen MM et al (UCSF). Obstet Gynecol (Aug) 2008; 112:333-40

* also Fleischner Society

CTPA in Pregnancy

• bolus triggering with short start delays,

• high flow rates or high contrast medium concentration,

• preferential use of fast CT systems and

• the use of low kVp CT techniques.

• shallow respiration

Schaefer-Prokof C & Procof M (Amsterdam & Ultrecht MC)Eur Radiol 18:1705-6

CTPA Imaging Findings

Acute PE – CTPA Findings

• Occlusion or filling defect– Branching – Multiple – more than 1 level

• Vessel enlargement• Polo-mint or railway track• Acute angle• High attenuation (C-)• Ancillary

– Wedge shape opacities– Linear bands– Oligemia

central, bilateral PE

Wittram C, et al. RadioGraphics 2004; 24:1219Patel S & Kazerooni EA. AJR 2005;185:135

Segmental PE

Subsegmental PE

polo mint

Hyper-attenuated thrombus

Pulmonary InfarctionCentral Lucencies: 98% specificity & 46% sensitivity

Revel , MP et al Radiology 2007;244:875-882

Pulmonary Infarction

Revel , MP et al (Université Paris Descartes). Radiology (Sep) 2007;244:875-882

0 10 20 30 40 50 60

Vessel sign

Central lucencies

Air bronchogr.

Triangular shape

per cent

PE (50 pts) Ctrl (100 pts)

Acute PE: Ground Glass Opacities

Thoma P et al. Radiology 2009 Aug;250:721-729 (Erasmus U)


Acute PE induces GGO in unobstructed lung zones.

Redistribution of blood flow

Given constant cardiac output this happens at a pressure consistent with pulmonary edema

Pitfalls – Misdiagnosis

Technical• Poor bolus • Resp & Cardiac motion• High-Res. algorithm • Noisy images (large pts)• Streak artifacts (lines,

tubes, arms)• Beam hardening (SVC

dense contrast)

Interpretation• Lymph nodes• Pulmonary vein,• Mucoid impaction in

bronchi• Partial Volume

averaging • Tumor emboli

Wittram C, et al. RadioGraphics 2004; 24:1219Patel S & Kazerooni EA. AJR 2005;185:135

Technical Poor bolus, large patient, noisy imageProblems in subsegmental vessels

TechnicalBeam hardening from SVC High-resolution algorithm

TechnicalWindow selection

InterpretationLymph nodes

InterpretationPartial volume Tumor emboli

InterpretationMucoid impaction

Large PE

PE Occlusion Index

Qanadi et al. AJR 2001;176:1415 (U René Decatres, Paris)

• 10 segments in each lung• Obstruction factor (OF):

– 0=no, 1=partial, 2=total

• Max obstruction = 40• Occlusion index:

[(Segments x OF)] / 40

PE Outcome: prospective evaluation of CTPA clot burden & ECG score

• 105 PE of 523 CTPA. 13 deaths in 12 mo• No statistically significant association between

ECG score and CTPA clot burden at diagnosis and the 12-month all-cause mortality rate

dead alive

mean ECG score 2.4 2.03

mean clot burden 24% 22%

Subramaniam RM et al (Mayo) AJR (Jun)2008; 190:1599-1604

Acute RV failure / strain

• RV dilatation (RV/LV > 0.9)

• Hepatic vein reflux

• Deviation of IV septum to left

• PE Occlusion index > 60%

4 chamber view: RV/LV = 1

Acute RV failure / strainDeviation & bowing of septum to left – IVC & hepatic vein reflux

Copyright ©Radiological Society of North America, 2008

Lu, M. T. et al. Radiology 2008;246:281-287

Interval increase in RV/LV diameter ratios at CT as mortality predictor

Small PE

Incidental Subsegmental PE (ISPE)

Small Pulmonary Emboli

25

42

2

106

19

2

61

50

20

40

60

80

100

120

ISPE (67p) Inconcl (125p) Anticoag.

Clinicians' Response to Radiologists' Reports

No RxRXReturned

Eyer BA, et al AJR Feb 2005; 184:623-628. (Medical College of Wisconsin)

Small Pulmonary Emboli

Rx• Inadequate

cardiopulmonary reserve

• Acute DVT• Recurrent small PE

Withhold Rx • No or few risk factors

for VTE • Transient (surgery)

rather than persistent (cancer) risk factors

• Other CV disease that can explain symptoms

• Negative D-dimer

Goodman LR. Radiology 2005; 234:654 (Editorial) (Medical College of Wisconsin)

Chronic PE

Chronic Pulmonary Thromboembolism

Pulmonary artery• Occlusion• Eccentric thrombus• Crescent – obtuse• Thick wall• Band or web• CalcificationCollateral systemic• Bronchial etc

Pulmonary hypertension• ↑ PA > 29 mm (≥Ao)• ↑ RV (≥ LV)Parenchyma• Scars & pleural thickening• Mosaic pattern• Air trapping• Bronchiectasis

Wittram C, et al. RadioGraphics 2004; 24:1219Patel S & Kazerooni EA. AJR 2005;185:135Castaner E, et al. RadioGraphics 2009; 29:31

Chronic PEEccentric crescent thrombus Band

PA = Aorta

Chronic PEBronchial arteries, PA > Ao Thrombus calcification

Chronic PEScars & pleural thickening

Chronic PEMosaic pattern

Triple Rule-out

Triple Rule out: >250 HU PA, Ao & coronaries

Frauenfelder T et al (U Zurich) Eur Radiol 2008;on line

Chest pain CTA regiments

0

50

100

150

200

250

300

350

400

HU

PE Dissection Chest pain Gated

Mean attenuation in PA & Aorta

PA

Ao

Raptopoulos et al AJR 2006 (Jun, sup); 186:S346-56 (BIDMC)

Retrospective ECG gating

• Continuous data acquisition. Coronary imaging & function

• Only 20% used for coronary imaging (waste)

• Low pitch (~ 0.3) contributes to high radiation

• With ECG modulation mA drops to ~ 45% in the out-of-phase part of the cardiac cycle ( 30% in radiation)

Weustink A C et al. (Erasmus)Radiology 2009;252:53-60


Litmanovich D et al, Eur Radiol 2008 (Feb) 18:308-17 (BIDMC)Litmanovich D et al, Eur Radiol 2008 (Feb) 18:308-17 (BIDMC)

ECG Modulated Chest CTA: 25 ± 7 mSv

Gated Chest – triple R/OGated Chest – triple R/O

Gated Chest CTA

Litmanovitch et al, Eur Radiol 2008(Feb);18:308-17 (BIDMC)

56 pts (50-80 y)•25 normal •20 lung or pleura•11 vascular•16 coronary

"Triple Rule-Out" CoCTA protocol in ED pts w ACS• 197 Low-to-Moderate Risk ED patients

• 30 day follow up

• Important non coronary dx : 22 (11%)

• Important incidental dx : 27 (14%)

• Moderate & severe CAD : 22 (11%)

• Preclude additional cardiac testing in 175 pts

Takakuwa KM & Halpern EJ (Thomas Jefferson U): Radiology (Aug) 2008;248:438-446

Prospective ECG gating

• ECG is used to plan timing • 10% - 30% of the cardiac cycle. • 64-row scanner (4 cm scanning

span), 16 cm span for cardiac imaging is scanned in 7 cycles: step and shoot

• dropped radiation of CCTA to <5 mSV ~ Chest CT and < CCA & nuclear medicine.

• CCTA – becomes a viable clinical tool

Earls J P et al. Radiology 2008;246:742-753 (Fairfax)


2 separate tests?

Low dose prospective gated64-row MDCTPA

Gated Chest – triple R/O

• Fujioka C et al from Hiroshima U (AJR July 2009) 100 kV; 30 pts– estimated effective dose

~7.5 mSv.

• Shuman W et al at the U Washington (AJR June 2009) prospective CTA in 41 pts w/o & 31 w/ prosp gating:– mean effective dose 32 vs

for 9 mSv

0

10

20

30

40

50

60

70

1 2 3 4

Retro Prosp


Shuman, W. P. et al. AJR 2009;192:1662-1667

CA image quality.CA image quality.

Triple R/O: Scan setup and bolus-tracking images

Halpern E J Radiology 2009;252:332-345 (Thomas Jefferson U, Philadelphia)


TRO CT angiogram in 31-year-old woman with chest pain that was atypical for angina but without severe shortness of breath



TRO CT angiogram in 79-year-old woman with recent onset of vague chest discomfort



TRO CT angiogram in 51-year-old athletic man with no relevant cardiac history who presented with atypical chest pain while resting at home



TRO CT angiogram in a 74-year-old man with history of coronary disease and pulmonary embolism who presented with progressive chest pain over 6 months that became acutely

worse on the day of presentation



Conclusions

• CTPA an established test (including in pregnancy)• CTPA over utilized (preferred chest pain test) • Use D-Dimer in high risk pts moderately successful• Indirect venography, Small PE management &

Thrombus burden assessment: controversial• RV size changes: important prognostic sign• Iodine delivery rate, Shallow inspiration• Consider radiation risk, 100 kVp• Triple rule out

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CTPA 2009 Vassilios Raptopoulos, MD Longwood Non-invasive Cardiac Imaging Seminar Beth Israel...

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