Page 1 of 55

How to perform a brilliant EP (pulmonary arteries angioCT)report

Poster No.: C-0461

Congress: ECR 2013

Type: Educational Exhibit

Authors: U. Sobrino Castro, I. Herráez Ortega, C. Antolín Pérez, A. FuentesMorán, S. Sánchez Campos, J. D. Samper Wamba; Leon/ES

Keywords: Structured reporting, CT-Angiography, Cardiovascular system,Thorax

DOI: 10.1594/ecr2013/C-0461

Any information contained in this pdf file is automatically generated from digital materialsubmitted to EPOS by third parties in the form of scientific presentations. Referencesto any names, marks, products, or services of third parties or hypertext links to third-party sites or information are provided solely as a convenience to you and do not inany way constitute or imply ECR's endorsement, sponsorship or recommendation of thethird party, information, product or service. ECR is not responsible for the content ofthese pages and does not make any representations regarding the content or accuracyof material in this file.As per copyright regulations, any unauthorised use of the material or parts thereof aswell as commercial reproduction or multiple distribution by any traditional or electronicallybased reproduction/publication method ist strictly prohibited.You agree to defend, indemnify, and hold ECR harmless from and against any and allclaims, damages, costs, and expenses, including attorneys' fees, arising from or relatedto your use of these pages.Please note: Links to movies, ppt slideshows and any other multimedia files are notavailable in the pdf version of presentations.www.myESR.org

Page 2 of 55

Learning objectives

The angioCT of the pulmonary arteries to discard PE (pulmonary embolism), is acommon challenge for the general radiologist on call.

PE is a potentially lethal pathology, so not only the correct diagnosis, but the accurateprognosis, are goals we should be able to achieve succesfully.

The aim of this electronic presentation is to bring and share an structured, completeand simple guide to help the radiologist coping with the challenge of reporting a PEstudy in a brilliant way, getting to an exact diagnosis and accurate prognosis.

Background

INTRODUCTION:

The angioCT of the pulmonary arteries to evaluate the presence of PE is a commonsituation for the radiologist on call.

The radiological report, apart from a legal must, is our communication pathway with thereferring physician, and should include data about the diagnosis and prognosis; thatway we help making the management, therapeutic decisions, and follow up of the patienteasier.

An essential issue to be able to do an accurate report is to optimize the quality of thestudy in order to improve our diagnostic tools, increasing the sensibility and sensitivityof the test.

TECHNICAL PARAMETERS:

Before even entering the CT area the patient should sign an informed consent form,thatallows us to use intravenous contrast material, ensuring that the patient has no knownallergies that could interfere.

Page 3 of 55

Patient preparation:place the patient in a supine position on the CT table, with the armsextended over the head (see figure n.2). The intravenous cannula should at least havea 20G caliber.

Fig. 2: Supine position of the pacientReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

IV contrast material: 50ml on a 4ml/sec flow and posterior washout of the cannula with30 ml of saline.

Kilovoltage: depending on the patient´s weight. 80Kv up to 70 kg, 100Kv from 70 to 100kg and 120 Kv over 100 kg.

Shooting: 6 second delay with bolus tracking technique, positioning the ROI in theprincipal pulmonary artery to 100 HU. It is important to do the acquisition with suspendedbreathing, not after deep inhale; to prevent contrast dilution in the right atrium due to arise on the venous return that we have when deeply inhaling.

Page 4 of 55

The direction of the study is caudo-craneal, to minimize the breathing artifacts in thelung bases.

Collimation less than 1 should be used (0,75).

The reconstruction protocol depends on the CT that we have, but it is vital importancethe filter and algorithm of reconstruction (20f for mediastinum and 60f for the lungs).

To identify all the arterial branches MPR and MIP reconstructions are very useful.

It is optional to do a CT venography of the lower limbs, that should include from thepelvis to the popliteal area in a delayed contrast phase 3 minutes later from the injectionof another 50 ml of contrast.

All these requirements are specified on figure 3.

Page 5 of 55

Fig. 3: CT protocols at our institutionReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

To be able to do a bright report it is necessary to know the particularities of the arterialsupply of the lungs, something that will definitely help us do the description of theradiological findings, the evaluation of the extension of the disease and so the follow up.

ANATOMY OF THE PULMONARY ARTERIES:

The anatomy of the pulmonary arteries (such as the bronchial and lobular anatomy) isnot symmetric, and has certain particularities. It is necessary to know them, in order todo a detailed and correct description, report it and to have a common language withpulmonologist, internal medicine doctors, Intensive care units and thoracic radiologists.

The main pulmonary artery (has its origin in the right ventricle, non-oxygeneted blood)is divided in two major branches: right and left principal pulmonary artery.

The right principal pulmonary artery leads the gas exchange in the right lung.

The right lung has three lobules (upper, mid and lowe) and three arterial lobular arteries(upper, mid and lower).

The RU (right upper) lobular is the first one, and has three segmental branches(anterior, apical and posterior).

After the exit of the RU lobular, the artery remaining is named the interlobular artery, thatis afterwards divided in RM (right mid) lobular (has two segmental: medial and lateral)and RL (right lower) lobular (first has a branch for the apical basal and then the basalpyramid that has 4 segmental: anterior, medial, lateral and posterior). See figure 4.

The left principal pulmonary artery is the intrusted of the gas exchange in the leftlung. The left lung only has two lobules, so the left pulmonary artery has only two lobularbranches: left upper and lower lobular arteries.

The left upper lobular is immediately divided in two branches, the apical (has twosegmental arteries: anterior and apical-posterior) and the lingular (has two segmental:upper and lower lingular).

The left lower lobe lobular artery has a first branch called the apical basal and thenthe basal pyramid that gives 3-4 segmental branches (anterio-medial, lateral andposterior). See figure 4.

Page 6 of 55

Fig. 4: Anatomy of the pulmonary arteriesReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ESAt the time of trying to identify each one of them, the bronchial anatomy (exactly thesame) is of great help.

The use of MPR (multiplanar reconstructions), mostly MIP images can be necessaryto recognize them, and very useful anytime. See figures 5 and 6 in the coronal and sagitalaxis.

Page 7 of 55

Fig. 5: Coronal MIP anatomyReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

Page 8 of 55

Fig. 6: Sagital MIP anatomyReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ESThe use of an imprecise or inadequate vocabulary leads us to pitfalls or wrong diagnosisthat we should avoid.

Images for this section:

Page 9 of 55

Fig. 2: Supine position of the pacient

Page 10 of 55

Fig. 3: CT protocols at our institution

Page 11 of 55

Fig. 4: Anatomy of the pulmonary arteries

Page 12 of 55

Fig. 5: Coronal MIP anatomy

Page 13 of 55

Fig. 6: Sagital MIP anatomy

Page 14 of 55

Fig. 7: Structured reading and report

Page 15 of 55

Fig. 8: Filling defects

Page 16 of 55

Fig. 9: Morphology of acute PE

Page 17 of 55

Fig. 10: Morphology of acute PE

Page 18 of 55

Fig. 11: Features of chronic PE

Page 19 of 55

Fig. 12: Features of chronic PE

Page 20 of 55

Fig. 13: Combined PE

Page 21 of 55

Fig. 14: PE extension

Page 22 of 55

Fig. 15: Sagital MIP as a help for PE extension

Page 23 of 55

Fig. 16: Parenchymal hemorrhage

Page 24 of 55

Fig. 17: Parenchymal Infarction

Page 25 of 55

Fig. 18: Atelectasis

Page 26 of 55

Fig. 19: Hypertension

Page 27 of 55

Fig. 21: RV overload

Page 28 of 55

Fig. 20: RV failure

Page 29 of 55

Fig. 22: Incidental Findings

Page 30 of 55

Fig. 23: Incidental findings

Page 31 of 55

Fig. 24: Incidental findings

Page 32 of 55

Imaging findings OR Procedure details

THE REPORT:

Once we have done the CT scan, and knowing the anatomy of the pulmonary arteries,we are ready to read the case and to do a complete, simple and useful report.

For the diagnosis and prognosis of a patient with PE (pulmonary embolism) the basicis to evaluate the presence of PE, the chronicity, extension and repercussion.

For the case reading and to do an structured report we propose the following scheme,that includes all the topics that we need to evaluate and include a precisely and clearlyin our report.

See figure 7.

Page 33 of 55

Fig. 7: Structured reading and reportReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

1. Filling defects

We should folow all the branches of the arterial pulmonary tree searching for filling defectsthat give us the diagnosis of PE.

If we have performed CT venography we should also try to find filling defect in the deepvenous system to give us the diagnosis of deep venous thrombus, which is the maincause of pulmonary embolism. See figure 8.

Fig. 8: Filling defectsReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

2.Type of thrombus: acute, chronic or combined

Page 34 of 55

Once the diagnosis of PE is made, it is essential to know if it is an acute or chronicprocess, this is very important for the management of the patient and has, of course,prognostic implications.

We can discriminate one from another for its morphology, location in the vessel, andthe angle that forms with the vessel´s wall.

Acute thrombus are classically centrally located in the lumen of the vessel, thuscausing dilatation of the lumen, occlusion (we can see pass of the contrast peripherallyin the lumen). When the thrombus is located eccentrically it typically forms an acuteangle with the vessel wall. See figures 9 and 10.

Fig. 9: Morphology of acute PEReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

Page 35 of 55

Fig. 10: Morphology of acute PEReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ESChronic Thrombi, generally are thrombi located eccentrically in the vessel, sometimesconcentric (recanalization is usually central) and they can have lineal or strip or webshape.

If they are eccentrically located mural thrombi, they tend to form obtuse angle with thevessel´s wall. When there is a chronic thrombus, these arteries usually have a smallerdiameter that the surrounding ones and the contralateral. See figures 11 and 12.

Page 36 of 55

Fig. 11: Features of chronic PEReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

Page 37 of 55

Fig. 12: Features of chronic PEReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

We can´t forget that having had a previous PE is a risk factor for PE, so sometimes wecan appreciate in one patient combined PE with chronic and acute thrombi at the sametime. See figure 13.

Page 38 of 55

Fig. 13: Combined PEReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

3. PE Extension

At this point is when we have to describe every branch affected, leaving clear if thereis one or both hemithorax involved, and most important if there are central (principaland lobular), peripheral (segmental and sub-segmental) or both branches affected.

For the correct identification of the arterial branches involved MPR and MIPreconstructions are of great help. See figures 14 and 15.

Page 39 of 55

Fig. 14: PE extensionReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

Page 40 of 55

Fig. 15: Sagital MIP as a help for PE extensionReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

4. Parenchymal affection

The parenchymal affection due to PE is unspecific and it is manifested, to start,as a ground-glass opacity (can see vessels through the opacity) in the areaaffected, generally segmental, with a triangular shape, with a pleural base, related tointrapanchymatous hemorrhage. See figure 16.

Page 41 of 55

Fig. 16: Parenchymal hemorrhageReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

As time goes by, if the occlusion remains, this ground-glass opacity will change intoconsolidation, with the same morphology and location, that is diagnostic of parenchymalinfarction. See figure 17.

Page 42 of 55

Fig. 17: Parenchymal InfarctionReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

Sometimes, the presence of blood clots in the bronchial tree secondary to PE, can causebronchial occlusion and therefore atelectasis. See figure 18.

Page 43 of 55

Fig. 18: AtelectasisReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

5. Secondary Pulmonary Hypertension

Acute and chronic PE can be the cause for pulmonary hypertension, this is somethingwe should know and bear in mind.

This is due to the impossibility of distributing the volemia from the right heart to the lung forthe presence of a thrombus in the pulmonary arteries; this causes a rising in the tensionof the arterial walls, and thus the increase of the diameter of the main pulmonaryartery. It is obvious that the larger and more centrally located the PE, the more likely itis to cause Pulmonary Hypertension.

This is a very important issue for the patient`s immediate management and for the initialprognosis too.

Page 44 of 55

We asses this by the caliber (diameter) of the main pulmonary artery.

The pulmonary artery is usually smaller than the aorta, and so the diameter should besmaller (although this diameter is not very valuable in patients with ectasis of the aortadue to hypertension, and so we don´t use it much in patients older than 50). The totalmeasure of this diameter should not be wider than 3 cm.

The right slice to measure the pulmonary artery is in the cone of the main pulmonaryartery, in an image where we see the bifurcation in the right and left pulmonary branches.See figure 19.

Fig. 19: HypertensionReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

The specificity of this sign rises up to a 100% when, apart from the rise of the diameterin the cone of the pulmonary artery, we see a rise in the diameter in segmental arteriescompared to the bronchus beside it, in at least three or more lobules.

Page 45 of 55

6. Right ventricle overload and failure

As there can be an increase in the pressure of the wall in the pulmonary artery, there canbe a right ventricle overload retrogradely.

The event of right ventricle overload and failure, within an acute pulmonary embolism, isthe main prognostic factor, and it is thus related with a higher morbidity and mortality.This must always be assesed and explicitely referred in our report (whether it existsor not), because it is going to change the monitoring, treatment and also the unit ofadmittance in hospital (frequently ICU whe we get to this point).

Generally, what we are going to see is a widening in the right cavities of the heart,that translates for overload, and it can even cause contrast material reflux to theinferior vena cava and suprahepatic veins, indicating failure, (these both findingsshould appear together and don´t consider them isolated). See figure 20 and 21.

Fig. 20: RV failure

Page 46 of 55

References: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

The measure of the right chambers should be done in a 4 chamber axis (see both atrium,ventricles and interventricular septa).

The cavity of the right ventricle should be smaller and narrower than the left one. A ratioRight ventricle/ Left ventricle > 1 indicates dilatation of the right ventricle, and sooverload. See image 21

Fig. 21: RV overloadReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

The interventricular septa usually presents a right convexity. If there is bowing so thatthis septa is straight or even has a left convexity, this is also a data os right ventricleoverload.

Within a chronic PE, the presence of a right ventricular wall wider than 4 mm meansoverload, and the thickening responds to an increased pressure in the ventricle.

Page 47 of 55

The measure for the right atrium is > 3,5 cm to say it is distended, but it is quitecontroversial and less useful.

7. Incidental findings

The incidental findings can get to be a frequent problem in these scans, but usuallyand luckily their resolution can wait and be less urgent.

We can never forget to have a look at the parenchyma with lung filter and window, andwe are rarely going to miss a pulmonary mass or a nodule. We can never forget to lookfor adenophaties, nor forget to examine the trachea-bronchial tree, that will help usdetect lesions that would have been undetectable otherwise. To illustrate this we havefigures 22, 23 and 24, all of them as neoplasic findings in three patients not known to besuffering from these diaseases previous to the CT.

Fig. 22: Incidental FindingsReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

Page 48 of 55

Fig. 23: Incidental findingsReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

Page 49 of 55

Fig. 24: Incidental findingsReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

8. Conclusion

Up to this point, our report has been merely descriptive.

To finish our mission with success, the report should include a clear and conciseconclusion, that systematicly and orderly runs through, at least, the first 6 point of thescheme, as illustrated in figure 25. This could take us one or two sentences.

Page 50 of 55

Fig. 25: SummaryReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ES

This way we will have a complete descriptive report, with a precise conclusion includingdiagnostic and prognostic data, essential for the correct management and follow upof the patient.

Conclusion

The angioCT of the pulmonary arteries is a common challange for the radiologist on call.

A systematic reading helps the diagnostic and prognostical approach and preventsfrom pitfalls.

What we necessarily have to evaluate in every CT is (following this suggestedorder): Presence of thrombus, chronicity, extension, parenchymatous repercussion, andpossible data on pulmonary hypertension and right ventricle failure.

Page 51 of 55

Performing an structured, simple and complete report is essential so that themanagement and follow up of the patient are accurate.

Images for this section:

Fig. 26: Conclusion

Page 52 of 55

References

SEE FIGURE 27

Fig. 27: ReferencesReferences: radiodiagnóstico, Complejo Asistencial Universitario de León - Leon/ESHan D, Lee KS, Franquet T, et al. Thrombotic and nonthrombotic pulmonary arterialembolism: spectrum of imaging #ndings. RadioGraphics 2003; 23:1521-1539.

Baque-Juston MC, Wells AU, Hansell DM. Pericardial thickening or effusion in patientswith pulmonary artery hypertension: a CT study. AJRm J Roentgenol 1999; 172:361-364.

. Schoepf UJ, Holzknecht N, Helmberger T, et al. Subsegmental pulmonary emboli:improved detection with thin-collimation multi-detector row spiral CT. Radiology 2002;222:483-490.

Page 53 of 55

Remy-Jardin M, Remy J, Artuad D, et al. Spiral CT of pulmonary embolism: technicalconsiderations and interpretive pitfalls. J Thorac Imaging 1997; 12:103-117.

Conrad Wittram, Michael M. Maher, Albert J. Yoo, Mannudeep K. Kalra,o-Anne O.Shepard, and Theresa C. McLoud .CT Angiography of Pulmonary Embolism: DiagnosticCriteria and Causes of Misdiagnosis Radiographics September 2004 24:5 1219-1238

Benoît Ghaye, Alexandre Ghuysen, Pierre-Julien Bruyere, vincent D'Orio,and RobertF. Dondelinger Can CT Pulmonary Angiography Allow Assessment of Severity andPrognosis in Patients Presenting with Pulmonary Embolism? What the Radiologist Needsto KnowRadiographics January-February 2006 26

Daehee Han, Kyung Soo Lee, Tomas Franquet, Nestor L. Müller, Tae Sung Kim,HojoongKim, O Jung Kwon, and Hong Sik Byun. Thrombotic and Nonthrombotic PulmonaryArterial Embolism: Spectrum of Imaging Findings.Radiographics November 2003 23:61521-1539 Douglas S. Katz,

•

Peter A. Loud, Dennis Bruce, Adam M. Gittleman,Richard Mueller, Donald L.Klippenstein, And Zachary D. Grossman. Combined CT Venography and PulmonaryAngiography: A Comprehensive ReviewRadiographics October 2002 22

Images for this section:

Page 54 of 55

Fig. 27: References

Page 55 of 55

Personal Information