Книги по МРТ КТ на английском языке / Thomas R., Connelly J., Burke C. - 100 cases in radiology - 2012

ANSWER 11

This is a diagnostically adequate posterior–anterior (PA) chest radiograph of an adult male patient. There is a 2.3 cm rounded mass lesion within the left mid zone adjacent to the left hilum that appears to cavitate in its inferior aspect. No other pulmonary parenchymal nodularity is seen. There is blunting of the costophrenic angles bilaterally which may represent either small pleural effusions or be longstanding related to pleural thickening. There is a background of emphysematous change as evidenced by lung hyperinflation and flattening of the hemidiaphragms. Bilateral gynaecomastia is also noted. The rounded lesion may represent a malignancy in the form of a lung primary in view of the clinical history, however a focus of infection or metastasis cannot be excluded. Correlation with old films is advised.

The suspicious nature of this pulmonary mass lesion warrants a computed tomography (CT) scan, which ideally should be performed with intravenous contrast. Although the chest X-ray only demonstrates a solitary lesion, a CT scan of the chest and abdomen is recommended. This allows characterization of both the lungs and mediastinum, and also assesses the solid abdominal viscera (e.g. liver and adrenals), which are sites of common involvement in disseminated lung cancer. Extending the CT to involve the abdomen allows for accurate staging of primary lung cancer, and the patient can be referred to the lung multidisciplinary meeting (MDM) for further discussion.

The CT scan confirms a background of centrilobular emphysema and a left lower lobe pulmonary nodule measuring 2.6 × 1.6 cm (Figure 11.2). This tethers the oblique fissure and demonstrates an adjacent airspace opacification with cavitation. No disease was seen in the contralateral lung, mediastinum or below the diaphragm. Findings are compatible with a primary bronchial malignancy.

Figure 11.2 Sagittal CT scan.

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The patient was then referred to the MDM. Time is an important factor to limit the spread of disease, and efficient transfer of patient care through the relevant specialities is of utmost importance to expedite definitive treatment.

A tissue diagnosis is important to obtain histological characterization of the lesion. Although cavitation and a history of smoking infers a likely squamous cell aetiology, histological confirmation is essential to tailor further chemotherapy or surgical treatment. The location of this lung primary would necessitate a CT-guided biopsy under the auspices of the interventional radiologists. A coaxial needle system is passed under CT guidance and local anaesthetic cover into the lesion, and a core biopsy sample taken (Figure 11.3). Patients should be consented for the risk of lung contusion and pneumothorax.

Figure 11.3 Biopsy under CT guidance.

A positron emission tomography (PET) scan is indicated in potentially operable tumours to assess nodal status and occult metastatic disease. This is required for complete disease staging and will dictate further treatment. If the PET scan confirms that this lesion is solitary and there is no evidence of nodal or metastatic spread, then the patient may be eligible for definitive surgery in the form of lobectomy if medically fit, although careful assessment will be needed in view of his significant COPD. Should the PET scan suggest inoperable or disseminated disease, then a chemotherapeutic treatment may be more appropriate.

A PET scan is a nuclear medicine scan, usually performed in combination with a CT scan. PET uses a radioactive isotope with a short half-life (e.g. fluorine-18 (F18)), which is biochemically incorporated into the functionally active glucose molecule fluorodeoxyglucose (FDG). It is used extensively in oncology imaging because the FDG–F18 is concentrated in metabolically active tissues, radiolabelling those tissues with high amounts of glucose uptake. Although there is physiological uptake in organs such as the brain, heart and liver, primary cancers and their metastases can also be detected by the PET scanner, as the F18 undergoes positron emission decay. The images obtained are fused with unenhanced, attenuation corrected CT images taken concurrently for anatomical correlation.

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Although not its primary function, CT can also allow further detection and assessment of both related and unrelated pathology. As well as primary staging, PET scanning can be used to assess response to treatment. Despite being an effective tool, its major limitations are related to cost (both of the scanner and in generating the isotope) and lesion size: small metastases (<1 cm) may not accumulate detectable levels of FDG–F18.

KEY POINTS

•A patient with a chest radiograph suspicious for lung cancer should be referred for a chest CT scan to characterize the lesion further.

•Lung biopsy can be performed under CT guidance for histological characterization.

•A PET scan is often used to assess suitability when planning the treatment for a patient with lung cancer.

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CASE 12: A SCHOOLMASTER WITH PROGRESSIVE

BREATHLESSNESS

History

A 64-year-old man is referred to the respiratory outpatient clinic for assessment. He gives a history of a shortness of breath which has been insidious in onset over the last 4 years. Over the last year, this has been associated with a dry cough which he cannot seem to clear despite several courses of antibiotics. He feels fatigued and had found it more difficult to complete a round of golf, which he used to do twice a week. His weight has remained steady and he denies orthopnoea. There is no relevant past medical history. He is a non-smoker and admits to social drinking only. He takes 75 mg aspirin daily on advice of his general practitioner (GP) but is not on any other regular medication. Occupationally, he is nearing retirement as a school headmaster and denies any history of occupational dust exposure. He lives at home with his wife and keeps no pets.

Examination

On examination, he is well perfused and not cyanosed, but has evidence of nail clubbing bilaterally. Lung expansion is reduced and auscultation demonstrates fine inspiratory crackles, more marked at the bases.

Prearranged lung function studies demonstrate a restrictive lung defect and a chest radiograph was taken for assessment (Figure 12.1).

Figure 12.1 Chest radiograph.

Questions

•How would you describe the chest radiograph appearances?

•What would be the differential for these appearances?

•How is the idiopathic cause of this condition subclassified?

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ANSWER 12

This is a posterior–anterior (PA) chest radiograph of an adult male patient. There is good alignment, inspiration and penetration. The heart and hila are of normal size with an illdefined ‘shaggy’ heart boarder. The lungs demonstrate volume loss, most marked at the bases with depression of the horizontal fissure on the right. There is reticular shadowing to the lung parenchyma in a subpleural distribution with relative sparing of the apices. There is no evidence of calcified lymph nodes or air–fluid levels within the oesophagus. Correlation with old radiographs is recommended, but the appearances are suggestive of pulmonary fibrosis.

Many people have difficulty with the descriptive terms of ‘reticular’ and ‘nodular’ shadowing. They are commonly used in chest radiograph reporting, implying clear differentials and distinction between infective and interstitial causes of lung disease. Reticulation describes lines that branch and interlace as a result of thickened interstitial septa between secondary pulmonary lobules. Nodularity, however, describes well-defined ‘dots’, which can vary in size and are predominantly caused by airspace opacification and imply an infective focus. Just to confuse matters, some conditions (e.g. sarcoidosis) can be both reticular and nodular in appearance.

In this scenario, the reticular pattern implies an underlying diagnosis of interstitial lung disease, with volume loss suggesting a fibrotic component. The causes of these appearances are numerous, and it is important to scrutinize the distribution of disease to help narrow the differential. The causes of lung fibrosis, divided between an apical and basal distribution, are listed in Table 12.1.

Table 12.1 Causes of lung fibrosis

By history alone and in the absence of ancillary features associated with connective tissue disease, a diagnosis of idiopathic pulmonary fibrosis is made in this patient. To confirm and subclassify the diagnosis, the patient should be referred for a high-resolution computed tomography (HRCT) chest scan. This is different from a normal ‘volume’ computed tomography (CT) scan of the chest and is an unenhanced study, providing high-resolution thin (1 mm) cuts of the lung parenchyma at 1 cm intervals (Figure 12.2).

This single image of the patient’s HRCT obtained within the lower zones of the chest demonstrates areas of disruption to the normal lung parenchyma with thickening of the interlobular septa causing a ‘honeycomb’ like appearance. These changes are predominantly confined to a subpleural distribution with preservation of the normal lung parenchyma centrally. This is characteristic of usual interstitial pneumonitis (UIP), a subtype of idiopathic pulmonary fibrosis. There is clinical importance in determining the likely

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subtype, as UIP is relatively insensitive to steroid therapy with a 45 per cent 5-year mortality.1 The other broad subtypes are:

•Non-specific interstitial pneumonitis (NSIP): Despite an often normal chest radiograph, appearances on HRCT are of patchy ground glass opacification with no clear zonal distribution. There is no evidence of honeycomb fibrosis and this subtype is more likely to respond to steroid therapy with an overall 5-year mortality of 11 per cent.1

•Desquamative interstitial pneumonitis (DIP): Seen predominantly in patients who smoke, appearances on chest radiograph and HRCT are of both subpleural ground glass opacification and honeycomb fibrosis. This is confined to the lower zones but is not associated with significant volume loss. DIP has a variable steroid response with a 50 per cent 5-year survival.1

Figure 12.2 High resolution chest CT scan.

KEY POINTS

•Reticular shadowing with parenchymal volume loss is the characteristic feature of pulmonary fibrosis on chest radiograph.

•It is important to scrutinise the distribution of disease within the lungs to help make the causative diagnosis.

•HRCT is integral in characterizing the type and extent of pulmonary fibrosis.

Reference

1.Dahnert, W. (2007) Radiology Review Manual, 6th edn. Philadelphia: Lippincott Williams and Wilkins.

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CASE 13: NUMB RIGHT ARM

History

A 50-year-old man presents with a history of an intermittently numb right arm that has become more of a problem recently after some heavy lifting. There is no history of trauma or surgery and there is no clear history of onset although the problem has been present for some months. He notices it most after sleeping, with forearm and hand numbness that wears off with movement. He also has an intermittent dull ache and impression of reduced strength, for example when trying to open jars. There is no history of Raynaud’s phenomenon, swelling or cold hand. There is no other significant medical history.

Examination

The arms are symmetrical. There are normal peripheral pulses. There is a subjective mild weakness on the right to flexion at the elbow with a slightly reduced biceps reflex. Reflexes and sensation are otherwise normal. No pulse changes are noted in hyperabduction or on deep inspiration with the head turned to the right side (Adson’s manoeuvre). In the right supraclavicular fossa a small hard lesion is palpable. The chest and abdomen are normal.

You arrange a chest radiograph (Figure 13.1a,b).

Figure 13.1 (a) Chest and (b) anterior–posterior (AP) cervical spine radiographs.

Questions

•What differential diagnoses are you considering?

•What does the radiograph show?

•What imaging or investigation would you do next?

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ANSWER 13

The differential diagnosis for this presentation is quite broad and can be narrowed down in broad classes. The symptoms are predominantly neurological and primary neurological causes such as spinal stenosis, tumour, cerebral infarct or multiple sclerosis or secondary causes including thoracic outlet syndrome affecting the brachial plexus, ulnar nerve compression and carpal tunnel syndrome should be considered. The possible weakness of elbow flexion and biceps reflex suggests a C5/C6 level lesion. There is less evidence for a vascular cause such as Raynaud’s disease, vasculitis or vascular compression. Other causes include trauma and soft tissue lesions such as a Pancoast tumour.

The radiograph shows bilateral cervical ribs. The mediastinum and lungs appear normal. The right cervical rib has a pseudoarthrosis (false joint) in the mid portion that corresponds with the hard palpable lesion in the supraclavicular fossa.

Although a vascular cause seems unlikely, an angiogram – selective imaging of vessels – may be helpful to check for compression of the subclavian vessels. Arteries or veins can be selectively studied by injection of contrast either by direct catheterization in combination with fluoroscopy, or intravenous injection and selective timing of the computed tomography (CT) scan. A catheter angiogram rather than a CT angiogram allows the patient to be put in different positions to try to induce the intermittent symptoms. The angiogram in Figure 13.2a proved to be normal. Given the predominantly neurological symptoms, further imaging should concentrate on identifying the position of the underlying lesion best done with magnetic resonance (MR) to examine soft tissue and nerve roots at the cervical spine and brachial plexus (Figure 13.2b). MR is less sensitive for cortical bone and a cervical spine radiograph for comparison is also helpful.

The patient’s symptoms are caused by the disc prolapse (demonstrated on MR) rather than thoracic outlet syndrome due to the cervical ribs.

Figure 13.2 (a) Fluoroscopic arteriogram. The arrow shows displacement but no compression of the right subclavian artery. (b) T2-weighted sagittal MR image showing degenerative changes at C5/6 with disc protrusion into the canal (arrow) also resulting in nerve root compression.

KEY POINTS

•Thoracic outlet syndrome can be subdivided into neurological, arterial and venous causes. The symptoms may help decide the most likely cause.

•Cervical ribs are a fairly common finding and often asymptomatic.

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CASE 14: JAUNDICE FOLLOWING CHOLECYSTECTOMY

History

A 41-year-old woman attended hospital for an ultrasound appointment requested by her general practitioner (GP). She had undergone a laparoscopic cholecystectomy 4 months previously and had recovered well, but over the last 3 weeks she had been complaining of increasing pain in the right upper quadrant and occasional itching. She denied any weight loss or jaundice, and reported normal appearances to her stool and urine. She is a non-drinker with no other notable medical history.

Examination

On examination she had slightly icteric sclera. She was comfortable at rest but had scratch marks on her upper arms from recent itching. The cardiovascular and respiratory examinations were normal, and her

abdomen was soft with slight tenderness of the right upper quadrant on deep palpation. There was no organomegaly.

Investigations showed a normal full blood count and renal function, but liver function showed an elevated bilirubin and alkaline phosphatase with normal transaminases and albumin levels. Her amylase was normal.

Figure 14.2

Questions

•What does the ultrasound demonstrate?

•What procedure is performed in Figure 14.2?

•What is interventional radiology?

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