Normal'Chest'X!Ray,%CT%and%MRI"Benigno'R'Santi'II,"MD,#FPCR!UST!FMS$!Department)of)Radiological)Sciences)!!(Magboo'C'2015,"Transcribed"from"PPT"and"Lecture;"few!information)lifted)from)Basic)Radiology)By)Chen,)2nd!Ed.)!"

!

! ! !!!!!!!!Radiography! Computed)Tomography! Magnetic)Resonance!

!Spatial'Resolution'and'Effective'Radiation'Dose'of'Thoracic'Imaging'Modalities"Spatial'Resolution'!Ability'to'define'/'differentiate'2'objects'apart%from%each%other%at%the%least%possible%distance!

(Think'of#pixels."If"an"image"has"better!resolution,+it+would+have+more% pixels,% therefore% would% appear% sharper' and' you' can'delineate(even(small(objects)!

"Modality! Resolution*(mm)! Dose%(mSv)!CXR! 0.08! 0.02$(PA),$!

0.04$(lateral)!DR! 0.17! 0.02$(PA),!

0.04$(lateral)!CT! 0.4! 8!MRI! 1.0! 0!Nuclear(Medicine! 7.0! 0.4!PET! 3.0! 7!Angiography! 0.13! 12!US! 0.3! 0!Background+Radiation!

N/A! 3"per"year!

Chest&X#Ray$has$better$spatial$resolution$than$CT$and$MRI!! Because'CXR'is'an'actual'picture'of'the'Chest!CT#MRI#are#digital#images,(which(have(been(computed!! (Similar:)a)photograph(taken(using(film(vs.(a(digital'camera)!"Indications*for*Chest*Radiography"

Diagnostic!! Cardiopulmonary-symptoms!

" Cough,'hemoptysis,'shortness'of'breath,'chest&pain,&etc.!

! Preoperative*for*thoracic*surgery!! Preoperative*if*known*cardiopulmonary*limitations!! Staging'of'thoracic'tumors'and'extrathoracic'

malignancies!! Infection!

" Pleural,(parenchymal,(mediastinal! Follow#up!

! Previously+diagnosed+cardiopulmonary+disease!" Pneumonia)resolution)to)exclude)

endobronchial%lesion!" Pulmonary*edema!

Monitoring(of(intensive(care(unit(patients!! Lung%disease!! Pleural'disease!! Lines&and&tubes&positions!

Monitoring(of(postoperative(patients!

"Radiographic+Film!in#between#two#Fluorescent+coatings!(also&called&intensifying)screens)!These$coatings)are$made$of$high$atomic'number'materials."It!can$absorb&x#rays%more!efficiently)(compared*to*the*film)*and$emit$photons,!which%can%now$be#efficiently#absorbed(by(the(x#ray$film$itself.!

!

!X#ray$films$are$valuable.$They$can$be$used$as$a$comparison$to$evaluate'progression'of'pre#existing(conditions%or%establish%a%if%a"finding"have"been"present"in"previous"examinations.!!Reading(Chest(Radiographs"Density(=(White(mass!Lucency'='Dark'(represents'air)!Infiltrate*=*Abnormal(density!!When%looking%at%an!X#Ray:%Compare%Right%and%Left%sides! Densities'!

o Ribs!(count'the'ribs!and$intercostal$spaces)! By#description:#on#CXR,#the#Anterior#and#

Posterior(Ribs(will(be(read(separately(because(of(the$oblique$orientation$of$the$ribs,$where$the$anterior(would(present(to!be#at#a#relatively#lower&level!

o Heart&and&its&Vascular(Markings! Equivalent+Lucency!(R#to#L)!

o Air!!Lungs&(equivalent&to&other&side)! Difficult(to(compare(when(the(shadow(of(the(

heart&interferes&(i.e.&lower&lung&fields)!o Divide&the&lungs&into&3&divisions&and&note$for$

the$vascular$markings.!Inner%Lung%Field%(Great%vessels%coming%from%hila)!Middle&Lung&Field&(intermediate&vessels)!Outer&Lung&Field&(very&small&vessels)!

o Trace&the&vascular&markings&to&differentiate&normal'from'an'infiltrate.!

!!!!!!!!!!!!!!!!!!!!O""""""""M""""""""""I"""""""""""! Equivalent+Side!!!!!!!!!!!!!!!!!!!!!!!!!Small!!!!!!!Intermediate!!!!!!!!Large!

!!!!!!

2"Factors"Affecting"Radiographic"Density"

"1.#Tissue&Depth!! Greater&thickness&=!more%dense!! Thick&tissues&will&attenuate&more&X#ray$beams$!! More%attenuation%=%More%Density!! Less$attenuation$=$More$Lucency!2.#Atomic#Weight!! The$Bone!is#the#densest#tissue#you#can#find!! ! Because'of'the'presence'of'Calcium!! Soft%Tissues:"Intermediate"density"!

(Water&Density)!! Lungs!very%Lucent%(Air!in#alveoli)!!

"Chest&X!Ray:"the"density"of"muscle,"blood"and"liver"are"very%close%together%(they%are%only%translated%as%intermediate)or)water&densities)!!Computed)Tomography:"can"differentiate"these"minute"differences)fairly%well!"Technique)in)doing)Proper)Chest)X!ray"

1. Upright(position!If#the#patient'lies'supine:!

There$is$pseudo#increase(in(the(transverse(diameter! The$level$of$the$diaphragm$may$be$deviated!

Note:&the&diaphragm&upon&CXR&examination&is&usually&described&in&halves.!

Right&hemi"diaphragm!o Usually'at'the'level'of'the'10th!

posterior(rib!o Can$normally$be$higher$than$the$

left%(due%so%the%Liver%being%positioned)on#the#Right#side)!

Left%hemi"diaphragm)!o Should'not"be"higher"than"the"Right!!!

2. Inhale'Deeply! Take%the%X#ray$at#the#end#of#a#moderately#

deep$inspiratory$effort! This%is%done%to%inflate%the%lungs!

o Demonstrate*normal*lucency!3. Postero#Anterior!

The$film$is$positioned$in$front$of$the$patient! The$X#ray$source$is$at$the$back$of$the$patient!

o Lessens%the%Magnification%of%the%Heart!o Can$be$mistakenly$interpreted$as$

cardiomegaly,!Note:!an#x"ray$is$like$casting$a$shadow,$the$greater$the$between$the$tube$and$the"film,"the"lesser%the%magnification.!!!

!!!!!!!!!!!!!!The$distance$between$the$tube$and$the$film!determines)magnification)and)clarity)or)sharpness.!It#is#usually#done#at!6"feet.!(An#AP#film,#taken#from#the#same#distance,#which#is#6#feet,%enlarges%the%shadow%of%the%heart%"!which%is%far%anterior(in(the(chest(and(makes(the(posterior(ribs(appear%more%horizontal)!!Changes(on(the(Chest(X#ray$corresponds$to$the$air$content$of$the$lungs,$specifically$in$the$Acinus'(which'contain'alveoli)!!!!!!!!!!!!

!!!!!

!

In#CXR,#The$Lungs$are$referred$to$as:!Upper%Lobe!and!Lower&lung&Field&(not%lobe)! They%are%separated%by%the$minor$fissure$and$

the$hila! Because'the'middle'lobe,'lower'lobes'and'

lingual'are'superimposed'on'each'other! The$Lower$lung$field$will$be$divided$by$the$

oblique(fissure(and(major(fissure! The$lower$lobes$are$more$posteriorly$located!

!!!!!!!!!!

The$left$image%shows%the%right%minor&fissure&(A)&and&the&inferior&borders'(B)'of'the'Major'fissures'bilaterally.!The$right$image$shows%the%superior%border%of%the%major%fissures%(B)%bilaterally.!

!!!!!!!!!!!

!Azygous(Fissure!!

!Companion(Shadow(of(the(Clavicle."It#is#actually'just'soft'tissue,'and'should'not'be'mistaken'for'other'abnormalities!""

Companion(Shadow"Appearance(of(a(smooth,(homogenous,(radiodensity(with(a"well#defined&margin!that$runs!parallel&with&a&bony&landmark.$They$represent$soft$tissue$that$overlies$the$respective)bony)landmark)in)profile.)They)may)or)may)not$always$be$present.!! Rib$companion$shadow!! Scapular(companion(shadow!! Clavicular)companion)shadow!!!

!Abnormal)Density)(Metallic)Density);)a)slug)of)a)bullet.!Note:&the&density&superior&to&the&right&clavicle&(we$can$be$able%to%determine%if%it%is%located%outside%of%the%thoracic%cavity'by'tracing'the'outlines)'this%density%is%just%actually%the$bandage'of'the'patient'(possibly!from%the%bullets%point&of&entry)!!!!!!""""""Posteroanterior*vs.*anteroposterior*radiograph.!On#the#anteroposterior*radiograph*(A)*of*this*normal*patient,*the*detector'is'against'the'back'of'the'patient.'A'combination'of'decreased'distance'between'the'source'and'the'patient'and'increased)distance&between&the&detector&and&the&anterior&mediastinal*structures*compared*with*the*posteroanterior*radiograph)(B))leads)to)magnification)of)the)heart.)""""""

!

Apico!lordotic(View!Anteroposterior*view*of*the*chest!Patient'is'in'hyperextended'position!X#ray!beam%goes%upward!

"!The$densities$emanating$from$the$ribs$and$clavicle$will$now$be$on#the#upper#segments!!""""""""""Lordotic'view.'In#this#patient#with#a#left#apical#neurofibroma,#the$abnormality$is$subtle$on$the$posteroanterior$radiograph$(A),%but%the%lordotic(view((B)(improves(visualization(of(the(lung(apices,(and(the(neurofibroma((asterisk)(becomes(more(apparent."""""""""""""""""""""""""""""

Computed)Tomography""""""""""Principles*of*computed*tomography.*The$source$of$x#rays%and%the$detectors$are$on$opposite$sides$of$the$gantry$with$the$patient'at'the'center'of'the'gantry.'Radiation'that'crosses'the'patient'is'detected,'producing'a'projection'of'attenuation'information.*By*rotating*the*gantry*around*the*patient,&multiple(projections(are(obtained,(which(are(then(used(to(mathematically*reconstruct*tomographic*attenuation*images.*!!Advantage:*we*can*adjust*the*images*and*zero#in#on#specific#structures!Indications*for*Thoracic*Computed*Tomography"

Pulmonary"! Further'characterize'CXR'abnormality'(e.g.,'

nodule,(mediastinal(mass)!! !Detection(and(follow#up#of#neoplastic#

disease&(e.g.,&metastatic&sarcoma,&lymphoma)!! Characterization,of,lung,nodules!

!!!!!!Benign&vs.&indeterminate!! Parenchymal+lung+disease+(e.g.,+emphysema,%

interstitial)lung)disease,)infection)!! !Airway'disease!

!!!!!!Central(and(peripheral(airways!! Pleural'disease!

!!!!!!Empyema,(metastasis,(mesothelioma!! Post#surgical)complications!! Percutaneous+biopsy+guidance!! Localization*for*VATS!

Cardiac"! !Cardiac'abnormalities%on%CXR!! Cardiac'anatomy!! !!!Coronary'arteries!

!!!!!!Calcification,+patency+with+CTA!!!!!!!Aberrant(coronary(arteries!

! !!!Postcardiac*bypass*grafting*complications!!!!!!!Mediastinitis!

Vascular"! Aorta:'aneurysm,'trauma,'dissection,'

coarctation!! Pulmonary*arteries:(embolus,(pulmonary(

hypertension!! Venous:(SVC/brachiocephalic(vein(thrombus(

or#obstruction!!!!!!

"""""""Computed)tomography)imaging."On"a"mediastinal"window&(A),&the&lungs&are&mostly&black&and&the&mediastinum*and*chest*wall*are*emphasized.*On*a*lung#window#(B),#these#structures#are#white#and#the#fine%structures%of%the%lungs%are%emphasized.!"

"""""""

Lung%nodule%on%computed%tomography.%The$faint$nodule$projecting+at+the+right+lung+base+near+the+diaphragm+(A)+was$further$investigated$by$Computed$Tomography,+which%revealed%a%calcified%granuloma"

"

High%resolution%computed%tomography%allows&exquisite&visualization+of+the+fine+detail+of+the+lung+parenchyma+in+this+patient'with'Langerhan's'cell'histiocytosis.'!!

Coronal'and'sagittal'reconstructions.'Multiplanar)reconstruction*of*the*helical*projection*data*in*the*coronal*(A)*and$sagittal$(B)$planes$can$be$performed.$This$improves$visualization+of+some+structures,+such+as+the+lung+apices+and+the$great$vessels.$!

Maximal'intensity'projection'reconstructions.&Information*from%a%stack%of%images%representing%a%volume%can%be%combined%into%a%single%image%representing%for%each%pixel%the%maximum%value&of&that&pixel&through&the&volume,&shown&here&in&the&coronal'(A)'and'sagittal'(B)'planes.'!!

Three!dimensional*reconstructions.*Data$can$be$further$processed(to(produce(three#dimensional*images*with*shaded*surface(of(any(chest(structure,(such(as(the(heart,(mediastinum,(lungs&or&ribs.&!""""""""""""

Magnetic)Resonance)Imaging)(MRI)!

!Magnetic)properties)of)nucleus.)A)hydrogen)nucleus)has)two)important)magnetic)properties:)a)magnetic)moment,)represented(by(an(arrow(along(its(axis,(and(an(angular(momentum'or'spin.'!Indications*for*Thoracic*Magnetic*Resonance*Imaging"

Thoracic"! Chest&wall&neoplasm((especially(superior(

sulcus%tumors)!! Mediastinal*tumors*(e.g.,*bronchogenic*cysts)!! Lung%parenchyma:%limited,%experimental!! Thoracic(outlet(and(brachial(plexus!

Cardiac"! !Congenital*heart*disease:*shunts,*

complicated+anatomy!! !Myocardium!

!!!!!!Cardiomyopathy!!!!!!!Ischemic(disease!!!!!!!Hypertension!!!!!!!Right&ventricular&dysplasia!

! Pericardium:+thickening,+effusion,+tamponade,*pericardial*cyst!

! !Masses:&thrombus,&tumors!! Valves'(limited):'stenosis,'regurgitation!

Vascular"! "Aorta:'aneurysm,'trauma,'dissection,#

coarctation!! !Pulmonary*arteries:*embolus,*pulmonary*

hypertension!! !Venous:(SVC(thrombus(or(obstructionSVC,(

superior(vena(cava.!!!

Magnetic)Resonance)in)the)chest)is)only)helpful)as)far)as)the)mediastinum*and*the*thoracic*wall*is*concerned.!The$lung$parenchyma%is%seen%as%low#signal'areas'because'of'the'presence'of'air.!!"

"

Magnetic)resonance)angiography.)Magnetic)resonance)angiography*of*the*aorta*and*its*branches*is*useful*to*evaluate*aortic'dissection'(A).'Magnetic'resonance'angiography'of'the'pulmonary*arteries*enables*good*visualization*of*the*pulmonary*arteries*(B)*and*can*be*used*to*rule*out*pulmonary"embolism.)!""""""

!!