MRI and CT assessment of paranasal sinus involvement in nasopharyngeal carcinoma (NPC)

MRI and CT assessment of paranasal sinus involvement in nasopharyngeal carcinoma (NPC)

ABSTRACTS Assessment of lymph node status is critical for prognostic factors as involvement of the lymph node chain worsens prognosis significantly. A...

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ABSTRACTS Assessment of lymph node status is critical for prognostic factors as involvement of the lymph node chain worsens prognosis significantly. At present size criteria are used to establish whether the lymph nodes are involved or not. We compared the findings at C T with lymph node microdissection by the pathologist. Forty patients undergoing surgery for extra-cranial head and neck tumours underwent C T scanning, utilizing 5 m m contiguous slices, and 150 ml of iodinated contrast medium (300 mg/ml). All patients underwent surgery and several lymph nodes were removed, including obviously involved and macroscopically appearing normal nodes. All nodes were sectional and examined in their entirety for microscopic deposits. C T failed to detect lymph node involvement in all non-enlarged lymph nodes which were shown to harbour deposits pathologically. CT accurately predicts lymph node involvement when the nodes are enlarged but fails to predict involvement in pathologically involved but not enlarged nodes.

M R I AND CT A S S E S S M E N T OF P A R A N A S A L SINUS I N V O L V E M E N T IN N A S O P H A R Y N G E A L C A R C I N O M A (NPC) V. F. H. C H O N G and Y. F. F A N

Department of Diagnostic Radiology, Singapore General Hospital, Singapore Accurate assessment of t u m o u r extent is crucial in disease m a n a g e m e n t and prognosis. In a prospective study of 71 patients comparing the accuracy o f M R I and CT in the staging of NPC, 19 (27%) patients showed t u m o u r infiltration of the paranasal sinuses. Sphenoidal sinus involvement could be demonstrated in 18 (25%), maxillary sinus in four (6%) and ethmoidal sinus in three (4%) patients. A total of 25 sinuses were involved in these 19 patients. Tl, T2-weighted and G d - D T P A enhanced images were obtained in the axial, coronal and sagittal planes. Contrast-enhanced CT scans were performed in the axial and coronal planes. T u m o u r infiltration can be diagnosed with confidence in G d - D T P A enhanced images in all patients. T2-weighted images can reliably separate t u m o u r from inflammatory changes except in two patients. The accuracy is therefore 92% as compared with Gd-DTPA-enhanced M RI. As expected, CT scans are very helpful in demonstrating bony erosions. It is less helpful in differentiating t u m o u r from secondary inflammatory changes. However, in two patients with MRI positive findings, CT scan findings were negative for bony erosions giving rise to a false negative rate of 8%. This study shows Gd-DTPA-enhanced M R I to be more accurate than T2-weighted images and CT scanning in demonstrating t u m o u r involvement of the paranasal sinuses. However, C T scans are still valuable, especially with added coronal sections.

DAISY C H A I N L Y M P H NODES: EVIDENCE O F AGE D I F F E R E N C E S IN EASE OF V I S U A L I Z A T I O N A N D T H E CLINICAL IMPLICATIONS S. C. W A R D and C. M E T R E W E L I

Department of Radiology and Organ Imaging, Prince of Wales Hospital, Shatin, New Territories, Hong Kong Daisy chain lymph nodes in the hepatoduodenal ligament can be visualized by ultrasound in the majority of normal subjects. Nodes which are considerably smaller than the accepted lower limit of the normal range by computed tomographic criteria are identified, and an assessment of their internal structure can be made. Hepatoduodenal lymph nodes have been assessed in 100 patients with no clinical reason for lymphadenopathy. The percentage of patients in which nodes can be imaged decreases with age. Age related factors, such as increased a m o u n t of extra- and intra-abdominal fat, interposed gasfilled bowel and previous surgery contribute to poor visualization. Visualization of nodes of such small size has important implications for [he accepted range of 'normal' as previously defined by computed tomography, which is too high when compared with ultrasound. Furthermore, the criteria for abnormal nodes need to be improved in order to identify the presence of pathology more accurately.

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M A G N E T I C R E S O N A N C E I M A G I N G OF T H E L U N G IN CHRONIC PURULENT SPUTUM PRODUCTION: A COMPARISON WITH THIN SECTION COMPUTED TOMOGRAPHY B. T R O T M A N - D I C K E N S O N , A. U. WELLS, J. K E E G A N , R. H. M O H I A D D I N , P. J. C O L E and D. M. H A N S E L L

Host Defence Unit and Department of Radiology, Royal Brompton National Heart and Lung Hospital, London Magnetic resonance imaging (MRI) has not been used for the evaluation of patients with chronic purulent sputum production. A reliable radiation-free method o f diagnosing and/or monitoring bronchiectasis would have obvious advantages in clinical practice. We performed MRI scans and concurrent thin section computed tomography on 15 patients with chronic purulent sputum production. CT scans were performed on an Imatron Ultrafast scanner: 3 m m sections obtained at 10 m m intervals. M R I scans on a 1.5 T Picker machine: acquiring multi-slice cardiac gated fast spin-echo (7 ms) axial sections. Comparison was made between abnormal signal on M R I and the presence of bronchiectasis on CT. In 14/15 patients, bronchiectasis was evident on CT; in all but one patient, abnormal signal was seen on MRI. In the one patient with no bronchiectasis on CT, the M R I appearance was normal. Abnormal M R I signal was seen in 36/90 lobes; in 16 lobes, ring and/or tramline structures were evident but in the remaining 20 lobes, the abnormal signal was amorphous. Bronchiectasis was present in 63/90 lobes on CT; abnormal signal was seen on M RI in 34 of these 63 lobes (sensitivity of MR1 = 54%). In 27 lobes with normal appearance on CT, abnormal M R I signal was seen in two lobes (specificity of M R I = 93%). We conclude that abnormal lobar signal on M R I is strongly predictive of the presence of lobar bronchiectasis on C T (positive predictive value = 94%).

IS T H E A D M I S S I O N C H E S T R A D I O G R A P H A SENSITIVE I N D I C A T O R OF A I R W A Y AND P A R E N C H Y M A L L U N G D A M A G E F O L L O W I N G A C U T E I N H A L A T I O N I N J U R Y AND BURNS? C. W I T T R A M and J. B. K E N N Y

Department of Radiology and The Mersey Regional Plastic Surgery and Burns Intensive Care Unit, Whiston Hospital Trust, Whiston, Merseyside Inhalation injury is the principal cause of death in burns patients. Schatzki described the major radiological signs on a chest radiograph following acute inhalation injury and burns. The most recently published paper on the subject concludes that the initial chest radiograph is an important predictor o f significant smoke inhalation injuries enabling selection of patients likely to require ventilatory support. The medical records and admission chest radiographs of all patients requiring ventilatory support for respiratory failure following acute inhalation injury and burns over 3 years (total of 29) were retrospectively analysed for signs of inhalation injury. Four were excluded because o f a history of chronic bronchitis or cardiac failure. Thirteen had abnormal radiological signs of inhalation injury, which included oedema of a consolidatory or interstitial pattern, and linear opacities due to atelectasis. Twelve chest radiographs were normal. Inhalation injury in burns cases requires clinical, and often bronchoscopic and blood gas assessment. Although changes were noted on 13/25 chest radiographs, the admission chest radiograph is an insensitive indicator of airway and parenchymal lung damage following acute inhalation injury and burns. We recommend abandoning its routine use following admission unless the patient is symptomatic.

F U N C T I O N A L D I F F E R E N C E S IN F I B R O T I C A N D C E L L U L A R FIBROSING ALVEOLITIS: T H E R E L A T I O N S H I P B E T W E E N LUNG F U N C T I O N AND C O M P U T E D T O M O G R A P H Y A. D. K I N G , A. U. WELLS, R. M. D U BOIS, M. B. R U B E N S and D. M. H A N S E L L

Department of Radiology and Thoracic Medicine, Royal Brompton National Heart and Lung Hospital, London There are conflicting reports about the relationship between extent of fibrosis and/or inflammation and impairment of lung function tests (LFT).. Thin section CT provides a method to assess extent of disease and likely histological appearance. The aim of this retrospective study