Magnetic Resonance Venography & Venous Ultrasonography for Diagnosing Deep Venous Thrombosis:A Prospective Blinded Comparative Study

Prof. Shad Salim AkhtarMBBS, MD, MRCP(UK), FRCP (Edin), FACP(USA)

Consultant Medical OncologistMedical DirectorKFSH, PFOCBuraidah, Al-Qassim, Saudi Arabia

Scenario

45 female attends A & E Swelling left legPainful2 days duration

No other illnessNo drugsO/E

Left leg ?swollen, non tender, not hot

Questions?

Does she have DVT?Admit?Review latter?What test to ask for?Shall I anticoagulate her?

Deep Vein Thrombosis

Usually originates in deep veins of calf Venous sinuses of soleus & gastrocnemius

Rarely popliteal, femoral, iliac Symptoms and signs are not characteristic

Qaseem A et al: Ann Fam Med 2007; 5:57Cantwell CP et al: J Vasc Interv Radiol 2006; 17:163

Only 20-30% have actually DVT>50% are never diagnosed

Deep Vein Thrombosis

Incorrect diagnosis!Misdiagnosis

Increased risk of PEPost-thrombotic syndrome

Over diagnosisAnticoagulation related bleeding

Qaseem A etal: Ann Fam Med 2007; 5:57Cantwell CP etal: J Vasc Interv Radiol 2006; 17:163

Wells Prediction Rule for Predicting Pretest Probability of Deep Vein Thrombosis

low ≤0; intermediate 1-2; high ≥3: If symptoms in 2 legs assess more symptomatic leg

Wells PS et al: Lancet 1997; 350:1795

Deep Venous Thrombosis

Objective diagnosis is

essential

Ho WK et al: Med J Aust 2005; 182:476

DVT Diagnostic Tools

D-dimer assayContrast venography

Gold standardNot appropriate as the first test

Venous ultrasonographyComputed tomographic venographyMagnetic resonance imaging

Merli G: Am J Med 2005; 118 (8A):3S

Venous Ultrasonography-Accuracy

Site Sensitivity% Specificity%Proximal 94-100 98-99Distal 60-70 60

Kyrle PA, Eichenger S: Lancet 2005; 365: 1163–74

Venous Ultrasonography-Limitations

3-34% need repeated study at 1 wkLess accurate diagnosis below kneeLimited visualization of pelvic veinsDifficulty in diagnosing recurrencePoor sensitivity in asymptomatic

patients

Lensing AW et al: Lancet 1999; 353: 479

Venous Ultrasonography-Limitations

TechnicalOedemaWound Immobilization devicesTendernessObesity

DiagnosticOperator dependentRecannalized vs fresh thrombus!!

Kearon C et al; Ann Intern Med 1998; 128:663

MRV vs Venous USG Study

King Fahd Specialist Hospital/Prince Faisal Oncology Centre

ProspectiveBlindedNon randomizedApproved by institute research/ethics

committee

Patients & Methods

Inclusion criteriaPatients admitted with suspected DVTAge >=18 years age

Exclusion criteriaContraindications for MRVSymptoms for more than 2 weeksHistory of ipsilateral DVT

Patients & Methods

A data abstraction form was designedDetailed history takenPhysical examination conducted Procedures were explained to the patientInformed consent was soughtVU & MRV were performed within 48 hrs

of admission

Patients & Methods-Imaging Techniques

MRV Performed by trained radiographersSuperconducting magnet 1.5 Tesla unit

(GE, Signa Horizon, USA)45 cms body coil Time of flight with fat saturationThree imaging blocks from ankle to IVCBoth legs were examined simultaneouslyAcquisition time 45 minutes

Patients & Methods-Imaging Techniques

Venous ultrasonography Qualified radiologist

Blinded to the result of MRV Symptomatic limb examined 5-7 MHZ linear array transducer

(GE Logic 400, USA) Examination procedure

Compression Augmentation manoeuvres Colour doppler evaluation of whole limb Calf to iliac veins

Patients & Methods-Imaging Analysis

VU and MRV analysed by two radiologists BLINDED to other modality

MRV Venous segments read Coronal source data Standard imaging reconstruction techniques Patency normal flow Thrombosis low signal intensity in venous lumen

VUThrombosis

non compressibilityAbsent flowVisibility of thrombus in lumen

Findings recorded in a standard format

Patients & Methods-Imaging Analysis

Patients & Methods-Statistical analysis

Data computerizedCompared by Chi square test for paired

variables with Yate’s correctionP value <0.05 was considered significant

Results

No of patients 40Exclusions 9

Previous ipsilat DVT 2Symptoms > 2wks 2Pregnant 2 Implanted met device 1Refusal to consent 1VU technically difficult 1

Results

Male:Female::10: 21Age

Range 18-85 yrsMean females 33 (14.5)Mean males 44 (23.8)

Results-Symptoms

Pain 29 (93.5%)Swelling 26 (83.6%)

Duration of symptoms = 1-14 days (median 6 days)Duration of symptoms 1-14 days, median 6 days

Results-Signs

Sign No (%)Increase temp 14 (45.2) 3 cm difference in diameter Above knee 17 (54.8) Below knee only 8 (25.8) Redness 3 (9.7)

Results-Co morbidity

Co morbidity No (%)Surgery 6 (19.4)Post partum 4 (12.9)Malignancy 2 (6.4)Varicosities 2 (6.4)Trauma 1 (3.2)

Results-Detection of thrombus

Venous segment

Imaging Study

MRV (%) VU (%)

+ve -ve +ve -ve p value

Calf vein 12 (38.7) 19 (61.3) 8 (25.8) 23 (74.2) 0.42

Popliteal 14 (45.2) 17 (54.8) 15 (48.4) 16 (51.6) 1.00

Femoral 20 (64.5) 11 (35.4) 19 (61.3) 12 (38.7) 1.00

Iliac 19 (61.3) 12 (38.7) 7 (22.6) 24 (77.4) <0.05

IVC 5 (16.1) 26 (83.9) Not assessed

Top

a

Venous segment

Imaging Study

MRV (%) VU (%)

+ve -ve +ve -ve p value

Calf vein 12 (38.7) 19 (61.3) 8 (25.8) 23 (74.2) 0.42

Popliteal 14 (45.2) 17 (54.8) 15 (48.4) 16 (51.6) 1.00

Results-Detection of thrombus

Top

b

Venous segment

Imaging Study

MRV (%) VU (%)+ve -ve +ve -ve p value

Femoral 20 (64.5)

11 (35.4)

19 (61.3)

12 (38.7)

1.00

Results-Detection of thrombus

c

Top

Venous segment

Imaging Study

MRV (%) VU (%)+ve -ve +ve -ve p value

Iliac 19 (61.3)

12 (38.7)

7 (22.6)

24 (77.4)

<0.05

IVC 5 (16.1)

26 (83.9)

Not assessed

Venography MRDTI VU

Fraser DGW et al: Ann Intern Med. 2002;136:89-98

Cantwell CP etal: J Vasc Interv Radiol 2006; 17:163

Soleus muscle venous thrombosis

Axial true FISP image

Sensitivity and Specificity of True FISP MRV for DVT Detection by Segment and Overall

Venous Segment

Sensitivity (%) Specificity (%)

Iliac 100 100Femoral 100 98Popliteal 100 100Tibial & others 68 94Overall 87 98

Cantwell CP etal: J Vasc Interv Radiol 2006; 17:163

Conclusion

Missing true gold standard for DVTContrast venography most reliable Difficult & invasive

Can MRV be the “gold standard”Non-invasive No radiationAccurateComprehensive imaging Reproducible

Conclusion

Barriers to MRVLack of availability High costLong examination time

FutureScanners becoming plentiful CheaperRapid scanning speedCosts may decrease

Zahid Nabi MRCP (I), FCPS, Khalida Parveen Salim MD, MRCR (UK), Ahmad Salamah Balah MBBCh, MD, Mohammed Kamel Al Adli MD, CES

Prince Faisal Oncology Centre, King Fahd Specialist Hospital,

Buraidah Al-Qassim, Kingdom of Saudi Arabia

Co-Investigators