Clin. Radiol. (1978) 29,501-511 COMPUTED TOMOGRAPHY IN THE DIAGNOSIS OF DISEASES OF THE PARANASAL SINUSES W. ST. C. FORBES*, R. A. FAWCITT, I. ISHERWOOD, R. W,EBB and T. FARRINGTON

From the Department of Diagnostic Radiology, Stopford Building, Oxford Road, Manchester University, and Department of Otolaryngology, Manchester Royal Infirmary, Manchester The authors investigated 31 patients suffering from benign and malignant lesions of the paranasal sinuses. Clinical, conventional radiological methods and computed tomography were used. In benign lesions CT added little significant information to that obtained by conventional radiological methods. In malignant lesions, however, CT provides additional valuable information. It gives a clear picture of the pbsterior, superior and orbital extent of paranasal turnouts. It also shows the extent of the tumour into the infratemporal fossa.

Cranial computed tomography, introduced in 1973, had an early and profound effect on neurological diagnosis (Ambrose, 1973; Paxton and Ambrose, 1974). The earlier head scanner units, employing the water reference bag and small aperture were unsuitable for scanning the base of the skull and facial region. The introduction of the EMI Whole Body Scanner (CT5000, updated to CT5005) with its variable patient ring size, faster scanning time and higher resolution on the 320 x 320 matrix, has enabled examination of the orbits, sinuses, petrous bones, pharynx and neck to be made. It has also provided the opportunity for examining the head in other anatomical planes e.g. coronal section (Hammerschlag et al., 1977; Robertson, Taveras et al., 1977 ; Rothman et al., 1977; Tadmor et al., 1977). This study investigates the value of computed tomography in the diagnosis of disease of the nasal cavity, paranasal sinuses and post-nasal space. The potential advantages of computed tomography over conventional radiology are the ability of the former to permit better soft tissue discrimination and quantitative analysis of X-ray attenuation in tissue. This paper reports on the results of CT in a series of 31 patients with benign and malignant conditions of the paranasal sinuses.

Table 1

Diagnosis Oedematous polyp Acute sinusitis Chronic sinusitis Mucocoele External angular dermoid Osteoma Neurilemmoma Transitional cell papilloma Melanoma Carcinoma Antrum Ethmmds Palate Septum Post Nasal Space Lymphosarcoma Malignancy Unspecified

1 1 3 2 1 1 1 2 2 8 2 2 1 2 1 1

plain views of the region and where indicated, hypocyclodial polytomography. The CT examination was performed in the University Department of Diagnostic Radiology at the University of Manchester, Medical School. The clinical material included a range of benign and malignant tumours, as well as acute and chronic sinusitis, mucocoeles, oedematous polyps and a dermoid cyst (see Table 1). Some of the non-neoplastic cases were included as controls to determine whether CT could differentiate benign and maligMATERIALS AND METHODS nant soft tissue. Thirty-one patients were assessed clinically by the All patients were examined on the EMI Whole Department of Otolaryngology at the Manchester Body Scanner, CT5000 (updated to CT5005 during Royal Infirmary. This included a full clinical exami- the trial). The 10 in ring size and the slow scanning nation, examination under anaesthetic and biopsy. mode (70 s) were selected in each case. The image Routine radiological investigation included standard was viewed on the higher resolution 320 x 320 matrix, but magnified computed reconstructed * Research Fellow funded by EMI Medical.

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