Pulmonary Symptoms without Correlating Findings in the Chest Radiograph

Checklist:

Pulmonary Symptoms without Correlating Findings in the CXR

• Was a myocardial infarction ruled out?

• Has the possibility of a pulmonary embolus been considered?

• Are the symptoms suggestive of an aortic dissection?

head: He worries about a pulmonary embolism, which is the most serious cause of unexplained dyspnea. He wants a venogram or a Doppler ultrasound of the lower extremities and a ventilation/perfusion scan, possibly a pulmonary angiography after that—and he wants Giufeng and Ajay to organize all of it. Giufeng gives him her best irritated look and suggests bringing Mrs. Candi to the CT scanner at once to answer all questions with just one examination—a "one-stop-shop" procedure. That one examination would suffice to cover the whole differential, she declares. Ajay is really impressed and Reginald complies after just a little resistance.

But Those in the Dark Remain Unseen

Undira Candi (65) complains about sudden tremendous chest pain and increasing shortness of breath. An ECG and the laboratory tests have been ordered in the emergency room but the results are not out yet. The CXR is ready for inspection (Fig. 6.51). Giufeng scrutinizes it with great care while Ajay looks over her shoulder. At first glance she cannot find any abnormality. Ajay agrees. Based on their observations they rule out a relevant pulmonary venous congestion as a consequence of left heart failure in myocardial infarction. Doc Reginald, the registrar on call covering the emergency room, stops by and scratches his

• What Is Your Diagnosis?

Pulmonary embolism: Pulmonary embolism is a frequent disease and also frequently overlooked—in excess of 50%; the CXR tends to be normal.

f Most pulmonary embolisms are not diagnosed because i the entity is not considered at all.

Only in extensive lung embolism are platelike atelectases (Fig. 6.52), lung infarctions (Fig. 6.53a), and associated pleural effusions seen on the standard CXR. Owing to the lack of perfusion, the pulmonary vessels may constrict ("Westermark" sign), a phenomenon best appreciated in

I The Case of Undira Candi I

I The Case of Undira Candi I

Cxr Pulmonary Embolism
Fig. 6.51 Observe the CXR of Mrs. Candi. Do you agree with Giufeng and Ajay?

CT (Fig. 6.53a). The ventilation-perfusion scan shows a discrepancy between intact ventilation and missing perfusion to the affected segment of lung, also called "mismatch" (Fig. 6.54a).

f A comprehensive CT protocol for pulmonary embolism ¿ nowadays encompasses a CT angiography of the pulmonary arteries (Fig. 6.53b) and a CT venography (performed immediately afterwards and without the need for additional contrast medium administration) starting at the level of the knee joint and proceeding to the confluence of the common iliac veins at the bottom of the vena cava (Fig. 6.53c). Above that level, thrombosis is very rare. Patients with venous thrombosis below knee level do not require treatment with anticoagulation, therefore detection would not alter management significantly.

Aortic dissection: An aortic dissection starts with an inti-mal tear, frequently in the ascending aorta just above the valvular level, through which blood enters the aortic wall and separates the aortic wall layers. Aortic dissection occurs frequently in patients with arterial hypertension and those with Marfan syndrome. Excruciating pain and dyspnea occur as often as in pulmonary embolism. If the dissection blocks the origin of a coronary artery, myocardial infarction may ensue. CT angiography of the pulmonary vessels also depicts the aorta in a contrast medium phase that will also demonstrate aortic dissection. In order to exclude both entities in one scan session on a fast multidetector-row CT scanner, the scan delay after beginning of the contrast injection in the CT scanner may need to be increased compared to the exclusion of pulmonary embolus alone, or you need to scan twice in rapid succession in order to ensure that there is sufficient contrast in the aorta. It is very important to determine the involvement of the ascending aorta in aortic dissection (type A), because of the risk of myocardial infarction (Fig. 6.55a, b). A type A dissection thus requires immediate surgery. Fortunately, the cervical vessels exiting the arch often prevent the retrograde extension of dissections originating in the descending aortic arch into the ascending aorta (type B, Fig. 6.55c). Type B dissection is less dangerous and is most often managed conservatively unless relevant organ arteries are occluded. If this happens, the vascular surgeon or the interventional radiologist swings into action: The occluding dissection membrane is perforated with a special technique and/or a stent is applied to restore perfusion (Fig. 6.56).

I Pulmonary Embolism: Chest Radiograph

Fig. 6.52 Note the typical basilar platelike atelectasis that is seen in patients with pulmonary embolism but is certainly also a frequent finding in all patients unable to take a deep breath in (for example, after abdominal surgery). The most common finding in patients with pulmonary embolism is a normal CXR.

I Pulmonary Embolism: Diagnosis by CT

a Chest CT

a Chest CT

Plate Like Opacities Cxr

Fig. 6.53 a The opacity in the lower lobe shows the typical triangular shape of a vascular territory. This is a classic pulmonary infarction due to pulmonary embolism (left). The reduced perfusion of the right lung is also suggested by the loss of vascular markings (right). b The fresh embolic material is appreciated in both pulmonary arteries as central filling defects in the vessel and outlined by the administered intravenous contrast (arrows). An older embolus tends to cling to the vascular wall molded along its circumference. c CT venography shows the presumptive cause of the embolism—a thrombus in the left femoral vein (left) that extends up into the inferior vena cava (right). Only the more expensive and cumbersome MR venography rivals the reliability of CT for thrombus detection.

b CT angiography b CT angiography

Angiography Pulmonary Embolism

Fig. 6.53 a The opacity in the lower lobe shows the typical triangular shape of a vascular territory. This is a classic pulmonary infarction due to pulmonary embolism (left). The reduced perfusion of the right lung is also suggested by the loss of vascular markings (right). b The fresh embolic material is appreciated in both pulmonary arteries as central filling defects in the vessel and outlined by the administered intravenous contrast (arrows). An older embolus tends to cling to the vascular wall molded along its circumference. c CT venography shows the presumptive cause of the embolism—a thrombus in the left femoral vein (left) that extends up into the inferior vena cava (right). Only the more expensive and cumbersome MR venography rivals the reliability of CT for thrombus detection.

c CT venography c CT venography

Ventilation Perfusion Scan For

I Pulmonary Embolism: Ventilation/Perfusion Scintigraphy a m

Fig. 6.54a There is notable absence of radiotracer activity in the right upper lobe on perfusion imaging. b On ventilation images, aerosolized radiotracer is normally distributed to the right upper lobe. This mismatch of ventilation and perfusion images points to a pulmonary embolism. With the advent of advanced spiral CT protocols, the importance of this method

Venogram Protocols

Fig. 6.55a On this scan the dissection membrane is clearly visible within the dilated ascending aorta: It is the detached intima. Along its margins, the intimal flap is still partially connected to the supporting adventitia by arclike fibers (arrow), a phenomenon that helps to decide which is the false lumen. In this case the false lumen is the outer lumen. b The large vessels tend to exit from the false lumen. Vessels may also be

Fig. 6.55a On this scan the dissection membrane is clearly visible within the dilated ascending aorta: It is the detached intima. Along its margins, the intimal flap is still partially connected to the supporting adventitia by arclike fibers (arrow), a phenomenon that helps to decide which is the false lumen. In this case the false lumen is the outer lumen. b The large vessels tend to exit from the false lumen. Vessels may also be

Dilated Ascending Aorta Symptoms

in the diagnosis of pulmonary embolism is decreasing continuously. As opposed to CT, the sensitivity of scintigraphy is also hampered by any coexisting pulmonary parenchymal abnormalities such as pneumonia or atelectasis, which are common findings in many patients at increased risk for pulmonary embolus.

Fr obstructed, however. In this patient the outflow of the coronary arteries is still detectable (arrow), but an immediate surgical intervention was necessary. By the way, the aortic dissection is also visible—as in a—in the descending aorta. c Lastly, the dissection may also extend into larger branch vessels, such as the superior mesenteric artery (arrow).

Spiral Dissection Coronary Artery

Fig. 6.54a There is notable absence of radiotracer activity in the right upper lobe on perfusion imaging. b On ventilation images, aerosolized radiotracer is normally distributed to the right upper lobe. This mismatch of ventilation and perfusion images points to a pulmonary embolism. With the advent of advanced spiral CT protocols, the importance of this method

Angiogram Pulmonary Embolism Mesenteric Artery Angiogram

I Therapy of Aortic Dissection

Aorta Fenestration

Fig. 6.56 You see an abdominal aortic angiogram of a patient with an iatrogenic type B dissection complicated by extensive claudication. a The contrast-filled true lumen is compressed by the unopacified false lumen. The renal arteries are also not opacified. b After fenestration of the dissection membrane

Fig. 6.56 You see an abdominal aortic angiogram of a patient with an iatrogenic type B dissection complicated by extensive claudication. a The contrast-filled true lumen is compressed by the unopacified false lumen. The renal arteries are also not opacified. b After fenestration of the dissection membrane

Fig. 6.57 a This patient also reached the emergency room with the preliminary diagnosis of pulmonary embolism. The documented tumor masses around the right main bronchus proved to be non-Hodgkin lymphoma. b It could, of course, also have been an extensive bronchial carcinoma (arrow) such as in this patient.

Fig. 6.57 a This patient also reached the emergency room with the preliminary diagnosis of pulmonary embolism. The documented tumor masses around the right main bronchus proved to be non-Hodgkin lymphoma. b It could, of course, also have been an extensive bronchial carcinoma (arrow) such as in this patient.

Pneumonia: Pneumonia can demonstrate similar symptoms and may be all but invisible on plain CXRs—for example, if it is located in the dense retrocardiac area or if the patient is grossly overweight and difficult to image (see Fig. 6.11a). Again, CT will also diagnose this entity without problems.

Mediastinal/pulmonary tumor: A mediastinal or pulmonary tumor may also cause clinical symptoms that resemble pulmonary embolism (Fig. 6.57).

(arrow) with a balloon, the renal arteries are reperfused. c Because the patient remained symptomatic, the dissection membrane was reapproximated to the vessel wall by deploying a stent (a small expandable wire-mesh tube) distal to the fenestration. This procedure finally provided symptomatic relief.

Surgical Mesh Tubing

• Diagnosis: Giufeng has persuaded Doc Reginald. The immediate CT examination reveals the true problem in this case (Fig. 6.58). A type A aortic dissection is present that needs surgical attention "stante pede" (that is: while standing on this foot, immediately, on the double). Reginald is relieved to have the diagnosis and contacts the thoracic surgeon on call. The senior medical consultant, who has also been alerted, inquires who this bright young lady in the chest imaging unit might be.

I Non-Hodgkin Lymphoma

I The Case of Undira Candi II

I The Case of Undira Candi II

Lady Aorta
Fig. 6.58a A dissection membrane is well appreciated in the ascending as well as the descending aorta. The coronary arteries are in acute jeopardy. b In the abdomen, another problems becomes evident: The left kidney is no longer perfused.
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