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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5775_Библиотеки_им_академика_М_И_Перельмана
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A.Pancreaticadenocarcinoma
B.Pancreaticmucinouscystadenoma
C.Pancreaticserouscystadenoma
D.Pancreaticpseudocyst
AnswersandExplanations
1.AnswerB.Imageoftherightupperquadrantshowsring-downartifactarisingfromagas-filledloop
ofbowel.
In ring-down artifact, the transmitted ultrasound energy causes resonant vibrations within fluid
trapped between multiple gas bubbles. These vibrations create a continuous sound wave that is
transmittedback tothetransducer. This phenomenon is displayedas alineor series ofparallel bands
extendingposteriortoagascollection.Ring-downartifactoccursmostfrequentlybecauseofgasandhas
alsobeenshownwithmetal.
Reverberation artifacts (answer choice A) occur when the ultrasound signal reflects repeatedly
between highly reflective interfaces that are usually in the near field. This is seen as multiple
equidistantlyspacedlinearreflections.Comet-tailartifact(answerchoiceC)isaformofreverberation.
In this artifact,the two reflective interfaces and their sequential echoes are closely spaced. The later
echoeshave decreased amplituderesulting ina reverberation artifact with a triangular, tapered shape.
Twinkleartifact(answerchoiceD)isduetoaformofintrinsicnoisewithintheDopplercircuitryofthe
USmachineandiscommonlyobservedatcolorDopplerimagingwheninsonatingcertainroughreflective
surfaces.
References: Dillman JR, Kappil M, Weadock WJ, et al. Sonographic twinkling artifact for renal calculus detection: correlation with CT.
Radiology2011;259:911–916.
FeldmanMK,KatyalS,BlackwoodMS.USartifacts.RadioGraphics2009;29:1179–1189
HertzbergBS,MiddletonWD.Ultrasound:therequisites,3rded.Philadelphia,PA:Elsevier,2016:23.
2.AnswerD.Acousticimpedanceofamaterialisdefinedastheproductofthedensityofthemedium
andthespeedofsoundinthatmedium.Itisameasureofthestiffnessofatissue.Intheprovidedchoices,
acoustic impedance is lowest in air, followed by fat, muscle, and bone. Bone and metal have high
acousticimpedance.
Reference:RSNA.RSNA/AAPMradiologyphysicseducationalmodules.
3.AnswerB.Fresnelzoneisthenearfieldoftheultrasoundbeam.Itisnearthetransducerfaceandhas
aconvergingbeamprofile.ThefarfieldordivergingfieldoftheultrasoundbeamiscalledtheFraunhofer
zone.UltrasoundimagingnormallyusestheFresnelzone.
The length of the Fresnel zone is d2/4λ, where d is the diameter of the transducer and λ is the
wavelength.Therefore,Fresnelzoneincreaseswithincreasingtransducersizeandfrequency(i.e.,lower
wavelength).
Reference: BushbergJT,SeibertJA,LeidholdtEM. Theessential physics of medicalimaging,3rded. Philadelphia, PA: Wolters Kluwer
Health/LippincottWilliams&Wilkins,2011:520–521.
4.AnswerD.Inthisimage,thestructuresweareinterestedinevaluatingaredisplayedinthetophalfof
theimage,whereasthebottomhalfshowsinformationthatis notusefulordiagnostic.Decreasingdepth
would eliminate the nondiagnostic information and allow us to evaluate the pancreas at an increased
framerate.
Thefocalzone(answerchoiceA)shouldbesetatorjustbelowthestructureofinterest.Inthiscase,
thefocalzone(indicatedbytriangleonleftsideofimage)issetappropriately,justbelowthepancreas.
Lowering frequency (answer choice B) allows for increased penetration at the expense of decreased
resolution. In this case, the pancreas is in the near field, and thus, we do not need to increase our
penetration toevaluateit.Increasing gain (answerchoiceC) will amplify the ultrasoundsignalcausing
the image tohave anoverall brighter or more saturated look. Gainis setappropriately in this image.
Spatial compounding (answer choice E) reduces speckle and noise. Reducing the number of lines of
spatialcompoundingwillcausetheimagetoappearnoisier.Increasingspatialcompoundingmayreduce
diagnosticallyhelpfulartifactssuchasacousticshadow.
Reference:HangiandreouNJ.AAPM/RSNAphysicstutorialforresidents:topicsinUS.RadioGraphics2003;23(4):1019–1033.
5. Answer A. A blind-ending structure representing the appendix contains an echogenic shadowing
appendicolith.Theappendixisthickened at9mm. Otherimageson thestudy(notshown)demonstrated
the appendix to be noncompressible with fluid adjacent to its tip. Findings are diagnostic of acute
appendicitis. Sonographic evaluation of suspected acute appendicitis relies on the use of a highresolution, usually linear probe and graded compression to optimize appendiceal visualization. The
primarydiagnosticcriterionisathickenedappendix>6mmindiameter.Othersignsofacuteappendicitis
includelackofcompressibility,echogenicinflamed periappendiceal fat,hyperemia, appendicolith, and
periappendiceal fluid. Terminal ileitis can exhibit similar features, so careful assessment for a blindendingmorphologyisimportanttoavoidthispitfall.
References:BirnbaumBA,WilsonSR.Appendicitisatthemillennium.Radiology2000;215(2):337–348.
HertzbergBS,MiddletonWD.Ultrasound:therequisites,3rded.Philadelphia,PA:Elsevier,2016:208–209.
6.AnswerA.Axialresolutionisthe abilitytoseparatetwoclosely spacedobjectsinthedirectionof
theultrasoundbeam.Toavoidoverlapofreturningechoes,thedistancebetweenthetwoobjectsmustbe
atleastone-halfofthespatialpulselength.Spatialpulselength(SPL)isthenumberofcyclesemittedper
pulsebythetransducermultipliedbythewavelength.Decreasingthespatialpulselengthwillimprovethe
axialresolution.Thiscanbeachievedbyusingahigherfrequency,whichwillreducethewavelengthand
hencethespatialpulselength.Thetradeoffisdecreasedtissuepenetration.
Decreasingthe diameterofultrasoundbeam improves the lateral resolution,which is the ability to
separatetwocloselyplacedobjectsperpendiculartotheultrasoundbeamdirection.Thelateralresolution
is bestatthenearfield–farfieldinterfacewheretheeffective beam diameterisapproximatelyequalto
halfthetransducerdiameter.
Reference: BushbergJT,SeibertJA,LeidholdtEM. Theessential physics of medicalimaging,3rded. Philadelphia, PA: Wolters Kluwer
Health/LippincottWilliams&Wilkins,2011:561–562.
7a.AnswerA.Theimagesshowbothadilatedpancreaticductandadilatedcommonbileduct,witha
heterogeneous masslocatedin thepancreatic head.This imaging appearance is known as the“doubleduct”sign,whichisconsideredahallmarkforpancreaticheadcancer.Thedilatedpancreaticductshould
notbemistakenforthesplenicvein,whichislocatedposteriortothepancreas.Also,adilatedcommon
duct(CD)couldbeconfusedforavascularstructure.However, thelocationoftheCDtotheleftofthe
portalveinonthetransverseimageshouldindicatewhichanechoicstructureistheportalveinandwhich
istheCD.Color-flowimagingshouldhelpconfirmtheidentityoftheCD.
Reference:HertzbergBS,MiddletonWD.Ultrasound:therequisites,3rded.Philadelphia,PA:Elsevier,2016:185–186.
7b. Answer D. Majority of pancreatic cancers appear hypoechoic on ultrasound compared to the
surroundingpancreaticparenchyma.Pancreaticcancerisahypovasculartumor.Itcancauseconsiderable
desmoplasticreactionresultinginobstructionanddilatationofthepancreaticductandcommonbileduct.
Therefore,tumorsinthepancreaticheadareusuallydetectedwhentheyaresmallbecauseofearlybiliary
tractobstructionand jaundice compared to those in the body andtail, whichtendto present as larger
massesandwithvaguesymptoms.Approximately60%to70%pancreaticcancersariseinthehead,10%
to20%inthebody,and5%to10%inthetail.
Reference:HertzbergBS,MiddletonWD.Ultrasound:therequisites,3rded.Philadelphia,PA:Elsevier,2016:185–186.
8.AnswerA.Reflectionofultrasoundenergyataboundarybetweentwotissuesoccursbecauseofthe
differences in acoustic impedances of the two tissues. Air–tissue interfaces reflect almost all of the
incidentultrasoundbeambecauseoflargedifferencesinacousticimpedance betweenthosetwo media.
Therefore,gelisappliedbetweenthetransducerandskinsurfacetodisplaceairandthereforeminimize
differencesinacousticimpedance.
Reference:RSNA.RSNA/AAPMradiologyphysicseducationalmodules.
9. Answer C. The Plan-Do-Study-Act (PDSA) is an iterative four-step process used for quality
improvement. In this process,a specific perceived practice deficiencyisidentifiedandan appropriate
measurementis devised toassess the selectedissueduring theplanning phase. A predicted resultand
desiredperformance target are alsodetermined.Next, duringtheDophase, baselinemeasurementsare
collected.Onceanappropriatenumberofsamplesis collected,thedataare studiedandcomparedwith
the anticipated result and target. If the measured performance does not meet the target, potential root
causesandotherfactorsareexamined.Ifthemeasuredperformancedoesmeetthetarget,aplantosustain
the performance goal is instituted. During the Act phase, a plan for improvement is devised and
implemented basedontherootcausesandfactorsidentifiedduringtheStudyphase.ThePDSAcycleis
then repeated continuously until the goal is achieved, or may be intermittently used to confirm that a
performancegoalisbeingmaintained.
Reference:TheAmericanBoardofRadiology.Qualityandsafety domainspecification andresourceguide. Tucson,AZ: TheAmerican
BoardofRadiology,2016.
10. AnswerA. Because the angle of incidence andangle of reflectionof sound are the same butin
oppositedirections,agreaterproportionof thereflectedsoundwillbedirectedtowardtheprobewhen
thetransducerisheldperpendiculartoatissueboundary.Increasingtheangleoftheprobewilleventually
resultinallofthereflectedenergytobedirectedcompletelyawayfromtheprobesothatthe echowill
notbedetectedatall.
Refraction occurswhenthebeampropagatesobliquelythroughtissueboundariesthrough whichthe
speed of sound changes. This will result in mislocalization and sometimes artifactual duplication of
anatomic structures. Refraction also results in defocusing and weakening of the ultrasound beam,
compromisingpenetrationandvisualizationofdeepertissues.
Reference:HertzbergBS,MiddletonWD.Ultrasound:therequisites,3rded.Philadelphia,PA:Elsevier,2016:22.
11. AnswerB.Lymphomatousinvolvementofthe coloninthispatientresultsinatypicalsonographic
appearanceduetotumor infiltration—hypoechoic,concentric,long-segmentbowelwallthickeningwith
destruction ofthewall layers anda central echogenicarea with dirtyshadowing correspondingto airfilled residual lumen. The peripheral hypoechoic thickened wall simulates renal cortex, and central
echogenicareasimulatesrenalsinusfat;hencethename.
Wall-echoshadow(WES)signisdescribedforcholelithiasis.Yin–yangsignisacolorDopplersign
of pseudoaneurysm. Onion skin sign has been described for testicular epidermoid and mucocele of
appendix.
References:HertzbergBS,MiddletonWD.Ultrasound:therequisites,3rded.Philadelphia,PA:Elsevier,2016:204,206.
LedermannHP,BörnerN,StrunkH,etal.Bowelwallthickeningontransabdominalsonography.AJRAmJRoentgenol2000;174(1):107–115.
RumackCM,WilsonSR,CharboneauWJ.Diagnosticultrasound,4thed.Philadelphia,PA:ElsevierHealthSciences,2011:270–280.
12.AnswerB.Thenormalspleenhasahomogeneousechotextureandishyperechoiccomparedtothe
liver and kidney. It measures up to 13 cm inlength and normally has a crescentic configuration. This
patient has an enlarged spleen that contains multiple solid hypoechoic lesions. Lymphangiomas are
composedofmultiplevariablysizedcysticspacesandareeitheranechoicorhyperechoicdependingon
the cyst size. Hemangiomas are typically hyperechoic. Splenic infarcts may be hypoechoic but are
expected to be wedge shaped and peripherally located. In an older patient with splenomegaly and
multiplehypoechoicsolidspleniclesions,alymphoproliferativeprocessmustbeconsidered.Thispatient
was diagnosed with chronic lymphocytic leukemia with leukemic splenic infiltration. The differential
diagnosis for solid hypoechoic splenic lesions is fairly extensive and includes lymphoma, metastases,
infarcts,abscesses,andsarcoidosis.
Reference:HertzbergBS,MiddletonWD.Ultrasound:therequisites,3rded.Philadelphia,PA:Elsevier,2016:192–203.
13a. Answer A. The ultrasound image shows heterogeneous pancreatic parenchyma with multiple
echogenic foci consistent with calcifications. Thecalcificationsmay or may not shadow dependingon
theirsize.Theimagingappearanceistypicalofchronicpancreatitis.
Chronic pancreatitis is aninflammatorydisease process that leads to progressive andirreversible
structural damage of the pancreas resulting in permanent dysfunction of both endocrine and exocrine
pancreatic function. Histologic changes include acinar cell loss, islet cell loss, inflammatory cell
infiltrates, and eventually irregular fibrosis. Patients present with abdominal pain, malabsorption, and
diabetes.
AlcoholabuseisthemostcommoncauseofchronicpancreatitisinWesterncountries,accountingfor
70% to 90% of cases (choice A is correct). Other etiologies include genetic (mutations in the cystic
fibrosis gene, hereditary pancreatitis), ductal obstruction (e.g., trauma, pseudocysts, stones, tumors,
pancreas divisum), tropical pancreatitis, systemic disease such as systemic lupus erythematosus,
hypertriglyceridemia,autoimmunepancreatitis,andidiopathicpancreatitis.
The classic sonographic sign of chronic pancreatitis is pancreatic calcifications. The intraductal
locationofthecalcificationsmaynotbeobviousonultrasound,wheretheymayseemscatteredthroughout
thepancreaticparenchymaasinthiscase.Othersonographicfindingsincludeductdilatation,pancreatic
atrophy,irregularcontours,andhyperechoicparenchymaduetofattydepositionandfibrosis.
References: Perez-Johnston R, Sainani NI, Sahani DV. Imaging of chronic pancreatitis (including groove and autoimmune pancreatitis).
RadiolClinNorthAm2012;50(3):447–466.
ZamboniGA,AmbrosettiMC,D’OnofrioM,etal.Ultrasonographyofthepancreas.RadiolClinNorthAm2012;50(3):395–406.
13b.AnswerB.Theultrasoundimageshowsalargeanechoiccysticlesionadjacenttotheheadofthe
pancreas. Multiple echogenic calcifications are againshownin thepancreas. Inthis setting,thelesion
mostlikelyrepresentsapancreaticpseudocyst.
Inapseudocyst,intracystic fluidwillbe expectedtohaveahighamylaselevelandalowCEAand
CA 19-9 level. High amylase levels can also be seen in IPMNs. CEA and CA 19-9 are also low in
pancreaticseroustumors.HighCEAlevelsareseeninmucinouscysticneoplasms.
Reference:Al-HawaryMM,FrancisIR,AndersonMA.Pancreaticsolidandcysticneoplasms.RadiolClinNorthAm2015;53(5):1037–1048.
14. AnswerC. Two important components of value inhealth care arequality and cost.Valueis the
efficient(lowcost)useofresources,whichyieldsadesiredlevelofquality.
Reference:TheAmericanBoardofRadiology.Qualityandsafety domainspecification andresourceguide. Tucson,AZ: TheAmerican
BoardofRadiology,2016.
15.AnswerC.Awedge-shapedperipheralhypoechoicspleniclesionwithacoarsenedechotexturewith
itsapexpointingtothehilumrepresentsanacutesplenicinfarct.Thediagnosisofsplenicinfarctioncan
be made with a high degree of confidence because of its characteristic shape, location, and coarse
echotexture. Splenic infarcts are a common cause of focal splenic lesions seen on imaging. The most
commonetiologies includeemboli or thrombosis ofthe splenic artery, splenic vein,or their branches.
Other etiologies include lymphoproliferative disorders andsickle cell anemia. Infarcts usuallybecome
smallerandhyperechoicwithtimeasthedevitalizedtissueisreplacedbyscarandwillbeaccompanied
by overlyingcapsularretraction.However,thesonographicappearance ofsplenicinfarctscanvary and
appearasmass-likeornodularfoci,requiringadditionalimagingwithCTorMRI.Althoughaworkupto
determine the etiology of splenic infarction is important, acute uncomplicated splenic infarcts usually
requireonly supportivetherapy. Potentialcomplications includeabscess, pseudocystformation,rupture,
andhemorrhage.
References: Goerg C, Schwerk WB. Splenic infarction: sonographic patterns, diagnosis, follow-up, and complications. Radiology
1990;174(3):803–807.
HertzbergBS,MiddletonWD.Ultrasound:therequisites,3rded.Philadelphia,PA:Elsevier,2016:198–201.
Rumack CM, Wilson SR, Charboneau WJ. Diagnostic ultrasound, 4th ed., 2 volume set. Philadelphia, PA: Elsevier Health Sciences,
2011:163.
16a.AnswerA.Anelongatedhypoechoicfocuswithinthesplenicparenchymacontainsnocolorflow
and represents a splenic laceration. No subcapsular or perisplenic collection is shown. The most
commonlyinjuredintra-abdominalorganfollowingblunttraumaisthespleen.Splenicinjuriesrangefrom
contusiontoshatteredspleen.Treatmentdecisionsarebasedonclinicalandhemodynamicparametersand
mayincludeconservativemanagement, embolization, andsurgery. Althoughsubcapsular hematomas are
alsocontainedwithinthespleniccapsule,theyshouldbelocatedalongtheperipheryofthespleen,follow
the splenic contour, and typically have a crescentic shape. Splenic infarcts and lacerations may be
sometimesdifficulttodistinguish byimaging, but the clinical history should permitdifferentiation.The
sensitivity of ultrasound for the detection of pseudoaneurysms is inferior to CT, but a sonographic
diagnosisrequiresdemonstrationofinternalflow.
16b. Answer C. Although splenic injuries can be demonstrated by ultrasound, CT provides a more
comprehensiveevaluationforsplenicinjuriesandperisplenichematomasaswellasassessmentforother
intra-abdominalorgansandvessels.
Reference: Rumack CM, Wilson SR, Charboneau WJ. Diagnostic ultrasound, 4th ed. Philadelphia, PA: Elsevier Health Sciences,
2011:165–167.
17. AnswerD. The differential diagnosis for splenic calcification is long and includes a variety of
etiologies. However, the size, morphology, and number of calcifications may provide a clue to their
cause. Multiple punctate calcifications are usually due to histoplasmosis, tuberculosis, or brucellosis.
When more than six calcified granulomas are identified, the most likely cause is histoplasmosis.
HistoplasmacapsulatumisafungusendemictotheOhioRiverValley.Thefungalsporesareinhaledand
formyeasts,which are thendepositedintothe bronchial lymph nodes. The organismsthen disseminate
hematogenously, and some may be filtered by the spleen, where they incite an inflammatory reaction,
eventuallyforminggranulomasandcalcifying.Tuberculosis usuallyresultsinfewer(<6)calcifications,
typically smaller than those associated with histoplasmosis. Brucellosis results in a few large rim-
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