CT: A Screening Modality for Lung Cancer, Colorectal Cancer, and ...

Jeff Velez, HMS IIIGillian Lieberman, MDJeff Velez, HMS IIIGillian Lieberman, MD

CT: A Screening Modality for CT: A Screening Modality for Lung Cancer, Colorectal Cancer, Lung Cancer, Colorectal Cancer,

and Heart Diseaseand Heart Disease

Jeff VelezJeff VelezHarvard Medical School Year IIIHarvard Medical School Year III

Gillian Lieberman, MDGillian Lieberman, MD

January 2003


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Leading Causes of Death Leading Causes of Death Due to Disease in U.S.Due to Disease in U.S.

#1#1——Cardiovascular disease: 710,760*Cardiovascular disease: 710,760*

#2#2——Lung Cancer: 154,900**Lung Cancer: 154,900**

#3#3——Colon CA: 56,300**Colon CA: 56,300**

*http://*http://www.cdc.gov/nchs/fastats/lcod.htmwww.cdc.gov/nchs/fastats/lcod.htm**Cancer Facts and Figures 2000, American Cancer Society**Cancer Facts and Figures 2000, American Cancer Society


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All Are Space Occupying LesionsAll Are Space Occupying Lesions

•• All three diseases are characterized by All three diseases are characterized by growing massesgrowing masses——plaques and tumorsplaques and tumors

•• These masses are readily detected when These masses are readily detected when contrasted with their environment on contrasted with their environment on appropriate xappropriate x--ray examination.ray examination.

CADCAD——Calcium with blood/soft tissueCalcium with blood/soft tissueLung CALung CA----Tumor with air filled alveoliTumor with air filled alveoliColon CAColon CA----Tumor with gas insufflated colonTumor with gas insufflated colon


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With Early With Early DxDx, All Three Can Be , All Three Can Be Positively ImpactedPositively Impacted

CAD: CAD: No Smoking, Diet, Exercise, No Smoking, Diet, Exercise, StatinsStatins, B, B--blockers, Surgical blockers, Surgical Intervention Intervention

Lung CA: No Smoking, Surgical ResectionLung CA: No Smoking, Surgical Resection

Colon CA: DietColon CA: Diet——High fiber, Polyp Removal, High fiber, Polyp Removal, Surgical ResectionSurgical Resection


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Benefits of Early DetectionBenefits of Early Detection

•• Early detection of mass with subsequent Early detection of mass with subsequent intervention significantly reduces mortality intervention significantly reduces mortality and morbidity in CVD and Colon CAand morbidity in CVD and Colon CA

•• Early detection and intervention with Lung Early detection and intervention with Lung CACA……Reduction in mortality and morbidity Reduction in mortality and morbidity is probable but uncertainis probable but uncertain


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Clinical RelevanceClinical Relevance

•• Nearly 1 million people die per year from Nearly 1 million people die per year from CAD, Lung CA, and Colon CACAD, Lung CA, and Colon CA

•• These diseases can be readily identified by These diseases can be readily identified by CT in early stagesCT in early stages

•• Once identified, these diseases can be Once identified, these diseases can be minimizedminimized

•• Early detection and prevention decreases Early detection and prevention decreases mortalitymortality


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CT Screening for CT Screening for Lung CancerLung Cancer


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Relevant Lung CA FactsRelevant Lung CA Facts

•• Lung Cancer manifests primarily when Lung Cancer manifests primarily when symptomatic or incidentally on CXR.symptomatic or incidentally on CXR.

•• Majority of patients are found with Stage II or Majority of patients are found with Stage II or greater Lung CA.greater Lung CA.

•• Stage II is characterized by a mass either < or > Stage II is characterized by a mass either < or > than 3 cm and lymph node metastasis.than 3 cm and lymph node metastasis.

•• Stage II prognosis is grimStage II prognosis is grim——5 year survival 5 year survival ~30%.~30%.


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Early Detection Using CT Finds Early Detection Using CT Finds Smaller Masses Smaller Masses

•• Screening with Single Slice Helical CT can Screening with Single Slice Helical CT can identify lesions on the order of several identify lesions on the order of several millimetersmillimeters

•• A majority of these tumors are categorized as A majority of these tumors are categorized as Stage I. (ELCAP Trial) Stage I. (ELCAP Trial)

•• Stage I is characterized by mass of <3cm and Stage I is characterized by mass of <3cm and no nodal metastasisno nodal metastasis

•• Stage I tumors have a markedly better 5 year Stage I tumors have a markedly better 5 year survival at ~80% survival at ~80%


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Does Early Detection = Reduced Does Early Detection = Reduced Mortality?Mortality?

•• Intuitive to believe that the overall mortality will Intuitive to believe that the overall mortality will be reducedbe reduced

•• However, there is no clinically proven reduction However, there is no clinically proven reduction in mortality with CT screeningin mortality with CT screening

•• This remains a topic of much debate and is the This remains a topic of much debate and is the basis for the National Lung Screening Trial basis for the National Lung Screening Trial (NLST)(NLST)

•• Randomized control trial, 50,000 subjects, Randomized control trial, 50,000 subjects, positive smoking history, 54positive smoking history, 54--75 yrs old, 75 yrs old, comparing CXR with chest CT in reducing comparing CXR with chest CT in reducing mortalitymortality


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Basic Concepts of CTBasic Concepts of CT——Intersecting Intersecting Lines of AttenuationLines of Attenuation


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What Is A Helical CT Scan?What Is A Helical CT Scan?•• Differs from conventional Differs from conventional CT in that a helical CT can CT in that a helical CT can continuously image the continuously image the bodybody

•• This increases speed of This increases speed of data acquisition and spatial data acquisition and spatial resolutionresolution

•• Maintains relatively low Maintains relatively low radiation dose (wide radiation dose (wide collimationcollimation——10mm)10mm)

•• Other relevant benefits Other relevant benefits include: improved 3D and include: improved 3D and volumetric analysis volumetric analysis


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How is Lung CA screening How is Lung CA screening procedure performed?procedure performed?

•• No preparation necessary No preparation necessary •• Total scanning time: 15 Total scanning time: 15 –– 20 seconds20 seconds•• High risk patientsHigh risk patients——positive smoking positive smoking

history and age 55 to 74 years oldhistory and age 55 to 74 years old•• Low radiation dose (10 mm collimation)Low radiation dose (10 mm collimation)


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SSCT of Pt. H.M.SSCT of Pt. H.M.——Stage I Lung CAStage I Lung CA

http//:bidmcpacs.caregroup.org


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Scout Film of Pt. H.M.Scout Film of Pt. H.M.



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Classic Locations of Lung CancerClassic Locations of Lung Cancer

Lung Cancer

Non-Small Cell(80%)

Small Cell(20%)

Squamous Cell(25-40%)

Adenocarcinoma(30-40%)

Large Cell(10%) Oat Cell Intermediate

www.vh.org


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Biopsy RevealedBiopsy Revealed…… AdenocarcinomaAdenocarcinoma

SSCT of Pt. H.M. Shows SSCT of Pt. H.M. Shows Peripheral Peripheral SpiculatedSpiculated NoduleNodule



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Measuring Growth of Nodules to Measuring Growth of Nodules to Monitor for Malignancy Monitor for Malignancy

Source: Source: HenschkeHenschke, C et al CT Screening for Lung Cancer. , C et al CT Screening for Lung Cancer. RadRad ClinClin of N of N AmerAmer May 2000May 2000


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Summary of CT Screening for Lung Summary of CT Screening for Lung CancerCancer

•• Spiral CT allows for fast scans with Spiral CT allows for fast scans with relatively high resolution and low radiation relatively high resolution and low radiation dose. dose. MultisliceMultislice CT scans can further CT scans can further increase speed and resolution.increase speed and resolution.

•• Malignant lung nodules can be detected in Malignant lung nodules can be detected in early curable stages.early curable stages.

•• NLST will determine if early detection can NLST will determine if early detection can reduce mortality.reduce mortality.


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CT Screening for CT Screening for Colorectal CancerColorectal Cancer


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Colorectal Cancer FactsColorectal Cancer Facts

•• Colorectal Cancer (CRC) is the second leading Colorectal Cancer (CRC) is the second leading cause of cancer mortality in the U.S.cause of cancer mortality in the U.S.

•• Principle behind screening is to intervene on the Principle behind screening is to intervene on the natural history of the adenoma to invasive natural history of the adenoma to invasive carcinoma development.carcinoma development.

•• Countless large clinical trials have shown a 30Countless large clinical trials have shown a 30-- 50% mortality reduction with screening.50% mortality reduction with screening.


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Screening ModalitiesScreening Modalities

•• FOBTFOBT•• Double Contrast Barium EnemaDouble Contrast Barium Enema•• Flexible Flexible SigmoidoscopySigmoidoscopy•• Conventional ColonoscopyConventional Colonoscopy•• CTCT--Colonoscopy (Virtual Colonoscopy)Colonoscopy (Virtual Colonoscopy)


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Poor Resolution with SSCT v. MSCTPoor Resolution with SSCT v. MSCT

•• CT colonoscopy requires large exam area CT colonoscopy requires large exam area (40cm) and breath hold (40cm) and breath hold

•• SingleSingle--Slice Helical CT is poor modality for Slice Helical CT is poor modality for detecting polyps < 10mm due to both detecting polyps < 10mm due to both insufficient spatial and temporal resolutioninsufficient spatial and temporal resolution

•• MultisliceMultislice CTCT——2x to 32x increase in acquisition 2x to 32x increase in acquisition speed with greater resolution of space and time speed with greater resolution of space and time


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MultisliceMultislice Helical CT ScannerHelical CT Scanner

•• Recent technological Recent technological advancements have advancements have allowed for the addition of allowed for the addition of multiple detectors.multiple detectors.

•• This allows for quicker This allows for quicker scans (10scans (10--20 seconds for 20 seconds for entire torso) and with finer entire torso) and with finer slices (collimation as low as slices (collimation as low as 1 mm)1 mm)

•• High sensitivity detecting High sensitivity detecting polypiodpolypiod lesions < 5mmlesions < 5mm


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MultisliceMultislice CT Scanner (16 Detectors)CT Scanner (16 Detectors)

Advantages over Single Slice Helical CT (SSCT):

- Speed: 500ms/ rotation

- Area covered: 4x,8x,16x

- Resolution: 1 mm collimation

Disadvantage:

- Radiation Dose: Greater than SSCT

www.medical.philips.com


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ProcedureProcedure•• Bowel cleansing 1 day prior Bowel cleansing 1 day prior •• Pt has CO2 or room air insufflated into rectum Pt has CO2 or room air insufflated into rectum

thru enema tip. thru enema tip. •• Supine imaging is performed Supine imaging is performed

with single breath hold. with single breath hold. •• Prone if image regions of interest Prone if image regions of interest

not availablenot available•• Total procedure time: 10 minutesTotal procedure time: 10 minutes•• Interpretation time: 15Interpretation time: 15--30 minutes30 minutes•• Total office time: 1 hrTotal office time: 1 hr

Courtesy of Dr. Martina Morrin, Virtual Colonoscopy Director, BIDMC Radiology


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2D Axial and 3D Imaging of 2D Axial and 3D Imaging of Ascending ColonAscending Colon



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2D Axial CT Image of Annular 2D Axial CT Image of Annular Carcinoma in Transverse ColonCarcinoma in Transverse Colon



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3D Reconstruction of CT Image of 3D Reconstruction of CT Image of Annular Carcinoma in Transverse Annular Carcinoma in Transverse

ColonColon



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Common Anatomic Sites of Common Anatomic Sites of Colorectal Colorectal NeoplasiaNeoplasia

RectumRectum——2020--30%30%

SigmoidSigmoid——35%35%

Descending ColonDescending Colon——55--8%8%

Transverse colonTransverse colon——15%15%

CecumCecum and and Ascending Ascending coloncolon——2525--35%35%

Netter’s Atlas of Human Anatomy CD-ROM 2nd Ed.


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Summary of CT Screening for CRCSummary of CT Screening for CRC——A A New Standard on the HorizonNew Standard on the Horizon

••CRC can be detected early, prevented from CRC can be detected early, prevented from progressing, and itprogressing, and it’’s mortality can be reduceds mortality can be reduced

••CRC has traditionally been detected by CRC has traditionally been detected by endoscopic colonoscopyendoscopic colonoscopy

••Development of MDCT scanners is helping to Development of MDCT scanners is helping to establish virtual colonoscopy as a clinically establish virtual colonoscopy as a clinically relevant screening tool. relevant screening tool. RCTsRCTs needed to verifyneeded to verify


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CT Screening for CADCT Screening for CAD


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How do you detect CAD with CT?How do you detect CAD with CT?

•• CT imaging of coronary artery calciumCT imaging of coronary artery calcium•• A CT scan of the heart using A CT scan of the heart using EBCT or MDCT EBCT or MDCT

along with ECG gating in order to visualize and along with ECG gating in order to visualize and quantitatequantitate the amount of calcium deposition in the amount of calcium deposition in the coronary arteriesthe coronary arteries

•• The fast speed with which images are The fast speed with which images are aquiredaquired (on the order of 10s of milliseconds) and ECG (on the order of 10s of milliseconds) and ECG gating allows for minimal blurring due to heart gating allows for minimal blurring due to heart motionmotion


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Hounsfield UnitsHounsfield Units (HU)(HU)

•• A unit of A unit of measurement used measurement used to measure ability of to measure ability of tissue to absorb an tissue to absorb an xx--ray beam.ray beam.

•• Different tissue have Different tissue have different HU values. different HU values. e.g. muscle/soft e.g. muscle/soft tissuetissue——40 HU40 HU

•• Used to provide Used to provide quantitative value to quantitative value to degree of coronary degree of coronary calcificationcalcification

•• Serve as a Serve as a prognostic tool in prognostic tool in determining determining likilihoodlikilihood of future of future coronary event.coronary event.Hounsfield, GN, Nobel Prize in Physiologu or Medicine

Lecture—Computed Medical Imaging, December 8, 1979


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Coronary Calcium ScoreCoronary Calcium Score

•• Represents the quantity of Ca in the coronary Represents the quantity of Ca in the coronary arteriesarteries

•• Indirect measure of Indirect measure of stenosisstenosis•• An aggregate of CT slices are integrated into An aggregate of CT slices are integrated into

one and areas of calcification and density are one and areas of calcification and density are automatically measured automatically measured

•• These 2 variables are calculated to yield a These 2 variables are calculated to yield a Coronary Calcium ScoreCoronary Calcium Score

•• Scores range from 0 to ~2000. Zero Scores range from 0 to ~2000. Zero representing no detectable coronary calciumrepresenting no detectable coronary calcium


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e.g. Distribution of Coronary e.g. Distribution of Coronary Calcium ScoresCalcium Scores

Raggi: Circulation, Volume 101(8): 850. February 29, 2000


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Relationship of Relationship of Coronary Coronary Calcium Calcium and CADand CAD

Budoff, Matthew J. Circulation 1996 Mar 1;93(5):898-904


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EBCTEBCT (Electron Beam Computed Tomography)(Electron Beam Computed Tomography)

http://www.bidmc.harvard.edu/radiology

1

4

3

2


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EBCT Image of Coronary Calcium EBCT Image of Coronary Calcium


LAD

Root of Aorta

Descending Aorta

LCX

Ramus


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MultisliceMultislice ((16 Detector) 16 Detector) CT Scan of CT Scan of Right MainRight Main, , Left MainLeft Main, , LADLAD

Courtesy of Dr. Melvin Clouse, Chief, BIDMC Radiology


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Anatomy of Coronary ArteriesAnatomy of Coronary Arteries

•• AortaAorta•• Left MainLeft Main•• Right MainRight Main•• LADLAD•• LCXLCX



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MultisliceMultislice (16 Detector) CT Image of (16 Detector) CT Image of Left Left MainMain and and Left CircumflexLeft Circumflex



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Aortic Root with Aortic Root with RightRight andand LeftLeft Main ArteriesMain Arteries



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Summary of CT Screening of Summary of CT Screening of Coronary CalciumCoronary Calcium

•• EBCT has been shown to detect early CADEBCT has been shown to detect early CAD•• Coronary Calcium Score can serves as a Coronary Calcium Score can serves as a

reliable prognostic factor for CAD and reliable prognostic factor for CAD and subsequent coronary eventssubsequent coronary events

•• In future, may become major prognostic In future, may become major prognostic tooltool

•• MDCT (16) as newest modality in MDCT (16) as newest modality in screening is promisingscreening is promising


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SUMMARYSUMMARY

By combining basic radiological By combining basic radiological principles of tissue contrast with the principles of tissue contrast with the advances in CT imaging that have advances in CT imaging that have occurred over the past decade, which occurred over the past decade, which include the development of the Helical CT, include the development of the Helical CT, MDCT, and EBCT, radiology is poised to MDCT, and EBCT, radiology is poised to become a major means of early detection become a major means of early detection and prevention of Cardiovascular Disease, and prevention of Cardiovascular Disease, Lung Cancer, and Colon Cancer.Lung Cancer, and Colon Cancer.


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ReferencesReferencesBudoffBudoff, Matthew J Ultrafast Computed Tomography as a Diagnostic , Matthew J Ultrafast Computed Tomography as a Diagnostic

Modality in the Detection of Coronary Artery Disease: A Modality in the Detection of Coronary Artery Disease: A Multicenter Study. Circulation, March 1996 Multicenter Study. Circulation, March 1996

Cancer Facts and Figures 2000, American Cancer Society 2002Cancer Facts and Figures 2000, American Cancer Society 2002HenschkeHenschke, C et al CT Screening for Lung Cancer. , C et al CT Screening for Lung Cancer. RadRad ClinClin of N of N

AmerAmer, May 2000, May 2000Hounsfield, GN Nobel Prize in Hounsfield, GN Nobel Prize in PhysiologuPhysiologu or Medicine Lectureor Medicine Lecture——

Computed Medical Imaging. December 1979Computed Medical Imaging. December 1979RaggiRaggi et al Identification of Patients at Increased Risk of First et al Identification of Patients at Increased Risk of First

Unheralded Acute Myocardial Infarction by ElectronUnheralded Acute Myocardial Infarction by Electron--Beam Beam Computed Tomography. Circulation, February 2000Computed Tomography. Circulation, February 2000

http//:http//:www.cdc.gov/nchs/fastats/lcod.htmwww.cdc.gov/nchs/fastats/lcod.htmhttp://http://www.bidmc.harvard.eduwww.bidmc.harvard.edu/radiology/radiologyNetterNetter’’s Atlas of Human Anatomy CDs Atlas of Human Anatomy CD--ROM 2ROM 2ndnd Ed.Ed.





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•• Gillian Lieberman, MDGillian Lieberman, MD•• Melvin Clouse, MDMelvin Clouse, MD•• Phillip Phillip BoiselleBoiselle, MD, MD•• Martina Martina MorrinMorrin, MD, MD•• Chad Chad BrecherBrecher, M.D. , M.D. •• Pamela Pamela LepkowskiLepkowski•• Larry Larry BarbarasBarbaras and Cara Lyn Dand Cara Lyn D’’amouramour

Special ThanksSpecial Thanks

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