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Role of Multidetector CT MDCT

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Title: Role of Multidetector CT MDCT


1
Role of Multidetector CT(MDCT)
  • Dr. Peter Johnson
  • Consultant Radiologist
  • University Hospital of the West Indies

2
  • What does MDCT mean ?

3
CT-Principle
4
Advantages of MDCT over SDCT
  • Improved spatial resolution
  • Improved temporal resolution

5
MDCT Spatial Resolution
  • 16 Slice scanners Isotrophic
  • No appreciable improvement in quality (spatial
    resolution) with gt 16 detectors

6
Multiplanar Reconstructions (MPR)
7
Multiplanar Reconstructions (MPR)
8
Multiplanar Reconstructions (MPR)
9
Multiplanar Reconstructions (MPR)
10
Volume Rendering
11
Surface Rendering
12
MDCT Temporal Resolution
  • gt number of detectors, greater volume covered per
    unit time
  • gt number of detectors, faster scanning
  • Better for CTA and Cardiac (esp)
  • Advantage of 64 slice over 16 slice etc.

13
Temporal Resolution
  • Useful for
  • Vascular work eg. CTA, CTV
  • Phased scanning eg. Liver, Kidneys
  • Functional work eg. CT Perfusion, Cardiac CT
  • Reduces scan time hence great for
  • Uncooperative patients
  • SOB
  • Confused (eg. Head injury etc)
  • Paediatric

14
  • Reduced Frequency of Sedation of Young
  • Children with Multisection Helical CT
  • Pappas John N., Donnelly Lane F., Frush Donald P.
  • CONCLUSION The rate of sedation was reduced
    threefold with multisection helical CT compared
    with standard helical CT, and the need for
    sedation was eliminated in some age groups.
  • Radiology 2000 215897-899

15
Temporal Resolution
16
Clinical Applications
  • General body imaging (Chest, Abdomen Pelvis)
  • Trauma
  • CT Angiography (CTA)
  • Cardiac CT
  • Virtual Colonoscopy (and other virtual endoscopy)
  • CT perfusion
  • Other

17
Clinical Applications
  • Cardiac.driving force in MDCT
  • CT Coronary Angiography
  • 4D Cardiac CT..ventricular function etc.
  • Cardiac calcium scoring

18
Coronary CTA
  • Interpreting the evidence How accurate is
    coronary computed
  • tomography angiography?
  • Abstract Coronary CT angiography (CTA)
    has evolved rapidly into a powerful diagnostic
    tool. More than 30 accuracy studies have reported
    accuracy results in gt2000 patients. A
    meta-analysis of 29 studies found per-patient
    accuracy of 96 sensitivity, 74 specificity, 83
    positive predictive value, and 94 negative
    predictive value. Several clinical studies
    support the safety and accuracy of coronary CTA
    for acute chest pain, after inconclusive stress
    testing, and in preoperative evaluation of
    patients before cardiac valve surgery. Accuracy
    studies suffer from selection bias because of the
    inclusion only of patients previously selected to
    undergo invasive angiography. This increases the
    incidence of true disease, raising apparent
    sensitivity and lowering negative predictive
    value, although the latter remains high at 94.
    CTA has relatively low accuracy for the
    quantitative assessment of stenosis severity. CTA
    accuracy studies show high figures for
    sensitivity and negative predictive value in
    detection of coronary lesions. CTA less
    accurately shows lesion severity, and
    intermediate-grade lesions require physiologic
    evaluation. Clinical studies support the
    effectiveness of CTA for exclusion of significant
    coronary disease.
  • Gilbert L. Raff
  • Journal of Cardiovascular Computed Tomography
    (2007) 1, 73-77

19
Coronary CTA
  • High sensitivity and negative predictive value
  • Good selection tool for excluding patients who
    are not candidates for invasive cardiac
    catheterization
  • Good screening tool
  • Less acurate at demonstrating lesion severity
  • These patients need intervention anyways !

20
Coronary CTA
  • The greater the detectors.better temporal
    resolution
  • MDCT scanners with greater detector numbers
    perform better than lower numbers
  • Coronary Arteries Diagnostic Performance of
    16-versus 64-Section Spiral CT
  • Compared with Invasive Coronary
    Angiography-Meta-Analysis
  • Conclusion Sixty-four-section spiral CT has
    significantly higher specificity and PPV on
  • a per-patient basis compared with 16-section CT
    for the detection of greater than
  • 50 stenosis of coronary arteries.
  • Michele Hamon, MD Remy Morello, MD John W.
    Riddell, MD Martial Hamon, MD
  • Radiology Volume 245 Number 3-December 2007

21
Pulmunary Thrombo-embolism
  • CT Pulmunary Angiography (CTPA) /- CT venography
  • Recommended by PIOPED II

22
CTPA
  • Suspected Acute Pulmonary Embolism Evaluation
    with Multi-Detector Row
  • CT versus Digital Subtraction Pulmonary
    Arteriography
  • PURPOSE To determine diagnostic accuracy of
    four-channel multi-detector row
  • computed tomography (CT) in emergency room and
    inpatient populations suspected
  • of having acute pulmonary embolism (PE) who
    prospectively underwent both CT and
  • pulmonary arteriography (PA).
  • CONCLUSION Multi-detector row CT has an accuracy
    of 91 in the depiction of
  • suspected acute PE when conventional PA is used
    as the reference standard.
  • Winer-Muram HT, Rydberg J, Johnson MS, Tarver RD,
    Williams MD, Shah H, Namyslowski J, Conces D,
    Jennings SG, Ying J,
  • Trerotola SO, Kopecky KK.
  • Radiology 2004 233806-815

23
Virtual Colonoscopy
  • Utilizes endo-luminal rendering
  • Similar bowel prep as optical colonoscopy
  • No need for sedation

24
  • Several studies demonstrate Virtual Colonoscopy
    performance on par with optical colonoscopy. Some
    indicate superior performance
  • Johnson CD, Dachman AH. CT colonography the next
    colon screening examination. Radiology
    2000216331341
  • Macari M, Bini EJ, Milano A, et al. Clinical
    significance of missed polyps at CT colonography.
    AJR Am J Roentgenol
  • 2004183127134.
  • Pickhardt PJ, Choi JR, Hwang I, et al. Computed
    tomographic virtual colonoscopy to screen for
    colorectal neoplasia in
  • asymptomatic adults. N Engl J Med
    200334921912200

25
Virtual ColonoscopyPatient Tolerance
  • Patients undergoing colorectal cancer screening
    prefer CT colonography to both colonoscopy and
    DCBE. The
  • majority of patients experience discomfort and
    inconvenience with cathartic bowel preparation.
  • Thomas M. Gluecker, MD, C. Daniel Johnson, MD,
    William S. Harmsen, MS, Kenneth P. Offord, MS,
    Ann M. Harris, BA, Lynn A.
  • Wilson, RN and David A. Ahlquist, MD
  • Radiology 2003227378-384
  • CT colonography was considered less painful and
    less difficult overall than colonoscopy and was
    the
  • preferred examination
  • Maria H. Svensson, MD, Elisabeth Svensson, PhD,
    Anders Lasson, MD and Mikael Hellström, MD, PhD
  • Radiology 2002222337-345
  • Patients preferred CT colonography to
    colonoscopy however, this preference decreased
    in time, while
  • outcome considerations gradually replaced
    temporary experiences of inconvenience
  • Rogier E. van Gelder, MD, Erwin Birnie, PhD,
    Jasper Florie, MD, Michiel P. Schutter, Joep F.
    Bartelsman, MD, Pleun Snel, MD, PhD,
  • Johan S. Laméris, MD, PhD, Gouke J. Bonsel, MD,
    PhD and Jaap Stoker, MD, Phd
  • Radiology 2004233328-337

26
Virtual Colonoscopy
27
Virtual Colonoscopy
28
Virtual Colonoscopy
  • No established international or even national
    protocol for
  • Performing study
  • Evaluating and reporting studies
  • Some differences in performance of VC software by
    manufacturer

29
Virtual Colonoscopy
  • Problems
  • Poor detection rate for flat lesions
  • Artefacts
  • No consensus in performance and reporting of
    studies
  • No tissue sampling
  • Patient compliance
  • Cost

30
Virtual Colonoscopy
  • Current Established Indications
  • Failed Optical Colonoscopy (OTC)
  • Evaluation of colon proximal to an obstructing
    lesion
  • Patients with contraindications to OTC
  • Future
  • Screening.pending outcomes of Trials

31
Brain Imaging
  • MDCT rarely adds to routine brain imaging
  • Useful for
  • CTA (SAH)
  • CT perfusion (Stroke)
  • ENT imaging

32
Cerebral CTA
  • Has replaced catheter angiography as the initial
    evaluation of the cause of acute subarachnoid
    haemorrhage in many centres

33
Cerebral CTA
  • MDCT Angiography for Detection and Quantification
    of Small Intracranial
  • Arteries Comparison with Conventional Catheter
    Angiography
  • CONCLUSION Except for the recurrent artery of
    Heubner and the anterior
  • choroidal artery, MDCT angiography depicted 90
    or more of all examined
  • small intracranial arteries detected with digital
    subtraction angiography. The
  • mean sensitivity was 0.91, and the mean
    specificity was 0.7.
  • Villablanca JP, Rodriguez FJ, Stockman T,
    Dahliwal S, Omura M, Hazany S, Sayre J.
  • AJR 2007 188593-602

34
Cerebral CTA
  • Intracranial Aneurysms Role of Multidetector CT
    Angiography
  • in Diagnosis and Endovascular Therapy Planning
  • Conclusion Multidetector CT angiography offers
    high diagnostic accuracy-
  • equivalent to that of DSA-in the detection of
    intracranial aneurysms. Also,
  • the possibility of coil embolization can be
    reliably determined with
  • multidetector CT angiography.
  • Karsten Papke, MD Christian K. Kuhl, MD Martin
    Fruth, MD Cornel Haupt, MD Martin
    Schlunz-Hendann, MD
  • Dieter Sauner, MD Martin Fiebich, PhD Alan Bani,
    MD Friedhelm Brassel, MD
  • Radiology Volume 244 Number 2-August 2007

35
Peripheral CTA
  • Good non-invasive tool for evaluating peripheral
    arterial disease.

36
Peripheral CTA
  • Aortoiliac and Lower Extremity Arteries Assessed
    with 16Detector Row CT
  • Angiography Prospective Comparison with Digital
    Subtraction Angiography
  • In this study, the improved spatial resolution
    obtained with a 16detector row CT
  • scanner is reflected in the total sensitivity and
    specificity (96 and 97, respectively,
  • for both readers) in the detection of
    hemodynamically significant arterial stenosis of
  • aortoiliac and lower extremity arteries. In
    particular, excellent sensitivities (ie, 96 and
  • 97 for readers 1 and 2, respectively) and
    specificities (ie, 95 and 96 for readers 1
  • and 2, respectively) for grading small
    popliteocrural arteries were obtained in this
  • study
  • Jürgen K. Willmann, MD, Bernhard Baumert, MD,
    Thomas Schertler, MD, Simon Wildermuth, MD,
    Thomas Pfammatter, MD,
  • Francis R. Verdun, PhD, Burkhardt Seifert, PhD,
    Borut Marincek, MD and Thomas Böhm, MD
  • Radiology 20052361083-1093

37
Peripheral CTA
38
Whole Body CT
  • Cost-effectiveness of Whole-Body CT Screening
  • Compared with routine care, whole-body CT
  • screening provided minimal gains in life
    expectancy
  • (0.016 6 years or 6 days) at an average
    additional cost
  • of 2513 per patient, or an incremental cost
  • effectiveness ratio of 151 000 per life-year
    gained
  • Molly T. Beinfeld, MPH, Eve Wittenberg, PhD and
    G. Scott Gazelle, MD, MPH, PhD

39
However.
  • MDCT is not indicated for everything !
  • It isnt indicated at all in certain cicumstances
  • Not the study of choice in many circumstances
  • Should be used with caution in some circumstances

40
e.g.
41
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43
Not the study of Choice
  • MRI
  • Intra and extra-axial intracranial tumours
  • Congenital brain anomalies
  • Myelopathy Radiculopathy (Traumatic
    Non-traumatic)

44
Not the study of Choice
  • Ultrasound
  • Initial evaluation of neonatal intracranial
    events e.g. Germinal Matrix Haemorrhage (CT not
    indicated for this pathology), ? Hydrocephalus.
  • Acute gynecologic events e.g. ? Ectopic, ruptured
    ovarian cysts, ovarian torsion

45
Use with caution
  • Pregnant patients (especially 1st trimester)
  • Paediatric patients
  • Radiation Effects

46
Radiation Dose
  • On the basis of such risk estimates and data on
    CT use from 1991 through
  • 1996, it has been estimated that about 0.4 of
    all cancers in the United States
  • may be attributable to the radiation from CT
    studies. By adjusting this
  • estimate for current CT use, this estimate might
    now be in the range of 1.5 to
  • 2.0
  • David J. Brenner, Ph.D., D.Sc., and Eric J. Hall,
    D.Phil., D.Sc.
  • NEJM 2007 3572277-2284

47
Radiation Risks
48
Radiation Dose
  • Relative to CT scanners from the early 1990s,
  • present-day MDCT scanners result in doses that
  • are 1.5 and -1.7 higher per unit mAs in head
  • and body phantoms, respectively.
  • Huda W, Vance A
  • AJR 2007 188540-546

49
However..
  • To date, no example of cancer definitely
    attributable to exposure to diagnostic x-ray
    doses has been reported.
  • Data represent extrapolated risk estimates
    related to known cancer incidences from exposure
    at Hiroshima and therapeutic Xray treatments in
    the early 20th century.

50
Radiation
  • Care and good judgement should be
    excersised.esp. paediatric population.
  • Risk/Benefit
  • Indications
  • Contraindications (including no indication !)

51
And so.
  • MDCT has revolutionized diagnostic imaging
  • Tremendous potential
  • High radiation dose
  • Not indicated for everything !
  • Not a replacement for other modalities

52
Thank you
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