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‘How I do’ CMR in HCM. Dr Sanjay Prasad, Royal Brompton Hospital London, UK. For SCMR August 2006 This presentation is posted for members of scmr as an educational guide – it represents the views and practices of the author, and not necessarily those of SCMR. . s.prasad@rbht.nhs.uk.

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how i do cmr in hcm

‘How I do’ CMR in HCM

Dr Sanjay Prasad, Royal Brompton Hospital

London, UK. For SCMR August 2006

This presentation is posted for members of scmr as an educational guide – it represents the views and practices of the author, and not necessarily those of SCMR.

s.prasad@rbht.nhs.uk

hypertrophic cardiomyopathy clinical aspects
Hypertrophic Cardiomyopathy: Clinical Aspects
  • Characterized by myocyte disarray, hypertrophy, and interstitial fibrosis
  • 90% of pts have familial disease
  • 10% de novo mutations
  • Increased risk of SCD
  • Adult prevalence 1:500 (Autosomal Dominant)
  • 1st degree-relatives -1:2 risk gene carrier
hcm diagnosis
HCM: Diagnosis
  • Unexplained hypertrophy
  • Measured wall thickness exceeds 2SD for gender-,age-, and BSA-matched populations
  • ≥ 1.5cm in absence of a recognized cause
  • There may be associated systolic anterior motion of the mitral valve leaflets and outflow tract obstruction
  • Multiple causative mutations in at least 10 different sarcomeric proteins
  • Variable phenotype and clinical outcome

Seidman et al 2002; Chien 2003

hcm histopathology myocyte disarray
HCM – HistopathologyMyocyte Disarray

Here with some associated fibrosis

cmr evaluation of hcm
CMR Evaluation of HCM
  • The first important aspect is determining LV and RV volumes, ejection fractions, maximal wall thickness and mass
  • We recommend the modified Simpson’s method rather than biplanar assessment since it makes no assumptions on cardiac morphology and is both more accurate and reproducible.
  • After piloting the 4ch and VLA views, retrospectively gated gradient echo cine slices are taken from the base to apex
  • Typically 7mm slices with a 3mm gap.
  • Usually myocardial coverage is achieved in 9-10 slices
cmr quantification
CMR Quantification

See the presentation ‘how I do’ LV volumes

Downloadable from www.scmr.org

hcm cine imaging
HCM: Cine Imaging
  • The key questions to address are: -
  • Presence, distribution, and severity of LVH and RVH. LV/RV mass and wall thickness
  • Extent of septal involvement
  • Distribution of hypertrophy in the variant forms of hypertrophic cardiomyopathy
functional assessment
Functional Assessment
  • Cine images are then acquired to determine if there is SAM and LVOTO.
  • SSFP images with retrospective gating recommended
hcm lvoto assessment
HCM: LVOTO Assessment
  • In-plane followed by through plane breath-hold flow mapping is performed to look at the peak velocity at the outflow tract (red-bar) and at the level of the aortic valve.
assessment of fibrosis
Assessment of Fibrosis
  • The presence of replacement fibrosis can be detected using the inversion recovery late enhancement technique following gadolinium-DTPA administration.
  • After all, fibrosis is the main component of chronic MI which is visible with the late enhancement technique
hcm a wide variety of scar
HCM – a wide variety of scar

2 patients. For the lower patient, scar is present and invisible without Gd-DTPA. Many patients have no detectablescar

slide16

Fibrosis -not like IHD

Picro sirius red stains collagen red.

In-vivo vs exvivo match

detection of fibrosis inversion recovery sequence
Detection of Fibrosis: Inversion Recovery Sequence
  • Dosage of Gd-DTPA: 0.1-0.2mmol/kg
  • At 0.1mmol/kg, images are usually acquired after about 5 minutes with a TI starting at ~340ms (every other heart beat).
  • At 0.2 mmol/kg, scans are acquired after about 15 minutes with a TI starting at ~250ms.
hcm detection of fibrosis
HCM: Detection of Fibrosis
  • LGE is predominantly seen in a patchy distribution and correlates with wall thickness.
  • Unlike in IHD, the subendocardium is not necessarily affected.
  • Unlike DCM, the distribution is typically more diffuse and not specific to mid-wall circumferential fibres.
detection of fibrosis inversion recovery sequence19
Detection of Fibrosis: Inversion Recovery Sequence
  • Tips to confirm fibrosis and not artefact:
  • Phase swap each slice
  • If mid-wall enhancement is seen, ensure TI is optimal and if need be, repeat the slice with a different TI
  • Cross-cut through any areas of suspected mid-wall enhancement
  • If subendocardial enhancement is seen, reconsider the diagnosis or assess if this reflects ‘bystander’ coronary disease
  • It is common to see some fibrosis around the LVOT and at the RV/LV septal insertion points
assessment of fibrosis20
Assessment of Fibrosis

late enhancement in the septum reflecting fibrosis

rv insertion point enhancement
RV insertion point enhancement

2 spots of enhancement at RV insertion points

  • The 3rd point is artefact

– Present AP phase encoding, disappears head-foot.

This is artefact ghosting across the image.

slide22

Other techniques: perfusion

Rest Perf

Late Gd

Perfusion defects in HCM – uncertain significance;

here matching enhancement

summary
Summary
  • Evaluate function, volumes, maximal wall thickness, distribution of hypertrophy and overall mass index.
  • Flow mapping to assess LVOTO
  • Presence of fibrosis important using inversion-recovery Gd-DTPA

s.prasad@rbht.nhs.uk