Computerized axial tomography in the detection of orbital space-occupying lesions.

Of 41 patients we examined for a suspected primary orbital tumor, 25 patients had evidence of a lesion either histologically, angiographically, or surgically. We examined nine of the 25 patients by means of an EMI-Scanner and 16 by a fine matrix addition (160 times 160 cells), and compared these results to those we received by axial tomography, orbital venography, and B-scan ultrasound. We also compared the absorption values of the recorded tumors. The EMI-Scanner had a diagnostic accuracy of 84%; orbital venography, 84%; axial hypocycloidal tomography, 71%; and ultrasound, 76%. The fine matrix scanner gave a preoperative diagnostic rate of 93% and defined optic nerve abnormalities accurately. However, EMI, scanning should complement existing noninvasive procedures and orbital venography.

Enhanced magnetic resonance imaging and subtraction techniques in postoperative evaluation of craniofacial resection for sinonasal malignancy.

The use of magnetic resonance imaging (MRI) enhanced with gadolinium. and diethylenetriamine pentaacetic acid (DTPA) in the preoperative evaluation of sinonasal malignancy is well established and has an accuracy of over 98%. Since 1979, 208 patients have undergone craniofacial resection at London's Institute of Laryngology & Otology, primarily for sinonasal neoplasia affecting the anterior skull base. Thirty-five "high-risk" patients had MRI at follow-up. The MRI scans were assessed before the patients were examined under anesthesia. MRI was assessed before examination under anesthesia and the results compared with histologic findings demonstrating a reasonable degree of positive correlation but one which is inferior to that found preoperatively (80%). An extension of this technique using the subtraction of T1-weighted MRI with Gd-DTPA highlights areas of increased vascularity, which significantly improves the ability to predict recurrence at the skull base and above the surgical repair in the anterior cranial fossa (94%).

Lacrimal gland tumours: the role of CT and conventional radiology.

The X-ray features of 66 lacrimal gland tumours, comprising 32 benign pleomorphic adenomas, 24 carcinomas and ten lymphomas, are reviewed. The role of radiology in the management of these patients is discussed. Although lacrimal gland tumours present no unique radiological appearances, the diagnosis and pathological type may be suggested by a combination of conventional radiography and CT scan. It is important to distinguish the pleomorphic adenoma clinically and radiologically from other lesions of the lacrimal gland, since this tumour must be excised in toto. Incisional biopsy or partial removal may result in a disastrous recurrence with seeding into bone and soft tissue. X-ray signs of malignancy in lacrimal gland tumours include invasion and sclerosis of the adjacent bone of the lacrimal fossa, calcification in the tumour and extension outside the lacrimal gland area shown on CT scan. The pre-operative diagnosis of malignancy was improved from 42% to 73% by CT. Indentation or enlargement of the lacrimal fossa was seen in 80% of benign pleomorphic adenomas. Although nonspecific, this sign in a patient with a painless lacrimal gland swelling of over 12 months' duration, without radiological evidence of malignancy, is strongly indicative of a benign tumour.

Axial hypocycloidal tomography of the orbits.

Axial hypocycloidal tomography has been applied to the investigation of 168 patients with suspected pathology in the orbit. Of these 75 had histological or angiographic confirmation of a space occupying lesion, and 55 patients showed positive evidence of abnormality. The X-ray changes observed include osteolysis and hyperostosis of the bony walls of the orbit, enlargement of the orbit-local and generalized, soft tissue abnormalities, and changes in the optic canal and superior orbital fissure. The most important evidence of the presence of a tumour or granuloma in the orbit was given by a positive "medial wall sign". This consists of a flattening or incurvation of the medial boundary of the orbit, best demonstrated by axial tomography. The sign was seen in 36.6 per cent of patients with proven intra-orbital space occupying lesions in the series. Axial hypocycloidal tomography is now an indispensable part of the diagnostic evaluation of patients with suspected orbital tumours and the procedure is complementary to other non-invasive investigations of the orbit, such as axial computerized tomography and ultrasonography.

Radiological changes associated with inverted papilloma of the nose and paranasal sinuses.

Inverted papilloma is an uncommon benign tumour of the nose and paranasal sinuses which has a characteristic histological pattern, high recurrence rate after surgery and may undergo malignant change. The X-ray features are reviewed in 60 patients with histologically confirmed tumours. Plain X-ray appearances were negative or non-specific in nearly half the patients. The changes shown on hypocycloidal tomography and on CT scan are more specific. A mass in the middle meatus of the nasal cavity extending into the adjacent maxillary antrum is highly suggestive of the tumour. Other features not hitherto reported are the presence of calcified areas within the tumour mass demonstrated by CT, and sclerosis and deformity of the walls of the sinuses involved by tumour.

The radiology of carcinoma of the ear.

Carcinoma arising in external auditory meatus, middle ear cleft or mastoid cavity has a poor prognosis unless treated at an early stage. Biopsy of any suspicious tissue is the key to early diagnosis but there are radiological features which may suggest the presence of a malignant neoplasm. An important role of radiology is the demonstration of the extent of disease and of spread beyond the confines of the temporal bone. The optimum regime of surgery and radiotherapy cannot be planned without this information. The radiological features of 47 aural carcinomas were reviewed. Thirty-two of the cases were examined by multidirectional tomography and six by computed tomography. The modes of spread of the neoplasm are discussed as well as the differential diagnosis. It is concluded that high resolution CT is now the optimum method of demonstrating tumour spread in the axial plane and frequently also in the coronal section. Lateral tomograms are necessary to show erosion of the walls of the external auditory meatus. Erosion of the bony septum separating the middle ear cavity from the carotid canal can be shown on coronal sections and is an important sign of spread anteriorly. Soft tissue extension into the infratemporal fossa may be demonstrated by high resolution CT.

The investigation of petro-mastoid tumours by high resolution CT.

Fifty-three patients with proven tumours of the petro-mastoid have been investigated by high-resolution computerized tomography. They comprised benign and malignant epithelial tumours; primary and secondary cholesteatomata; neurogenic and glomus tumours; meningiomas and secondary neoplasms. High resolution CT has the advantage of showing both bone erosion and the soft tissue mass of the tumour. This is important both for diagnosis and to show the extent of malignant disease in the petro-mastoid. The technique has become an integral part of the X-ray examination of these patients and in many respects has superseded other methods of investigation such as pluri-directional tomography and angiography.

The demonstration of tumours of the parapharyngeal space by magnetic resonance imaging.

Seven patients with parapharyngeal neck masses have been investigated by magnetic resonance imaging (MRI). These presented a wide spectrum of the tumours commonly found in this location. Magnetic resonance imaging has been shown to be superior to computed tomography in the investigation of these patients. The advantages include: better delineation of the tumour in three planes and the extent of its involvement in the head and neck, the demonstration of neck vessels without intravenous contrast, the demonstration of the vascular nature of the mass, and better soft-tissue demonstration of skull base involvement. It is concluded that CT is no longer necessary as a routine procedure for the investigation of parapharyngeal tumours when MRI is available.

CT evaluation of paranasal sinus tumours for cranio-facial resection.

Twenty-two patients with tumours of the paranasal sinuses had computerised tomography performed prior to cranio-facial resection. The findings of CT, histology and operative appearances are compared and a 78% correlation found. The radical approach offered by cranio-facial resection allows more accurate confirmation of CT findings than hitherto possible. The particular importance of CT scanning in relation to tumours of paranasal sinuses is discussed.

High-resolution computerized tomography of the petrous bone.

High-resolution computerized tomography (CT) has been used to investigate abnormalities of the ear and petrous bone. Congenital, traumatic, infective and neoplastic lesions have been evaluated in 30 patients with proven pathology. Some bone changes including abnormalities of the auditory ossicles have been better demonstrated than by conventional tomographic technigues, and high-resolution CT has some advantages in demonstrating both soft tissue abnormality and bone changes in the middle ear in primary neoplastic disease and secondary cholesteatoma. The absence of any practical means of taking sagittal sections with the present scanner design limits the usefulness of high resolution CT of the petrous bone, but this study has shown that the technique may now take its place as an important complementary procedure to pluridirectional tomography.

Congenital deformities of the middle and external ear.

Congenital deformities of the external and middle ears were shown by tomography in 246 patients. Surgical exploration has been undertaken at some time in many of these ears. The appearance of the tomograms and their significance were reviewed in the light of the operative findings and the authors' experience of congenital ear lesions. In nearly every case a middle ear cavity could be demonstrated although this varied from a normally aerated middle ear and mastoid in association with an isolated unilateral atresia of the external auditory meatus to a small slit-like hypotympanum in patients with craniofacial abnormalities. The ossicles were nearly always present but deformed. The typical appearances of the ossicles and the frequently aberrant pathways of the facial nerve are described.

Deformity of the labyrinth and internal auditory meatus in congenital deafness.

In congenital deafness it is important that the radiological examination should exclude any deformities of the bony labyrinth or internal auditory meatus as well as demonstrating lesions of the middle and external ears. Radiological assessment of inner ear abnormalities should be used as a guide both to the feasibility of reconstructive surgery to the middle and external ears and for the future training of the child. Inner ear abnormalities demonstrated by tomography in 56 patients are discussed in relation to the cochlea function. The importance of demonstrating the central bony spiral of the cochlea and of assessing the size and shape the internal auditory meatus is stressed.

Subtraction gadolinium enhanced magnetic resonance for head and neck imaging.

The subtraction method of Des Plantes has been applied to gadolinium enhanced magnetic resonance imaging (GdMR). Using short acquisition times, T1 weighted spin echo pulse sequences are made immediately before and after the intravenous administration of gadolinium DTPA. To avoid moving the patient from the scanning tunnel the venipuncture is made into the dorsum of the foot. The needle is placed in the vein prior to putting the patient into the scanner and is irrigated with saline while the control series is obtained. 42 patients with naso-sinus or skull base tumours have been successfully investigated by this technique and satisfactory subtraction studies are now obtained on all patients other than the claustrophobic. Subtraction GdMR provides the best demonstration of the effects of gadolinium DTPA on the magnetic resonance signal for both normal and abnormal tissues. The signal recorded on the subtraction image is dependent on tissue blood supply and provides a more accurate record of tumour extent than that shown by unsubtracted GdMR scans.

Magnetic resonance imaging in the evaluation of nose and paranasal sinus disease.

Fifty patients with a wide range of sinus disease have been examined by magnetic resonance. These included congenital conditions, inflammatory and allergic sinus disease, fungus infection, and both necrotising and non-necrotising granulomas. A variety of benign and malignant tumours have been investigated, including eight examples of juvenile angiofibroma and 19 malignant sinus tumours. This experience of magnetic resonance scanning has shown that it is superior to computed tomography in showing the extent of malignant disease and, provided the correct pulse sequences are employed, it is always possible to distinguish tumour from retained secretion or inflamed mucosa. The extent of intracranial invasion can also be optimally demonstrated. One of the advantages of the method is the direct three-plane imaging and multislice technique, which gives total coverage of the head and neck for the assessment of malignant disease. Tissue diagnosis in the paranasal sinuses is less important than the demonstration of tumour extent and distribution. Only one tumour (juvenile angiofibroma) showed diagnostic spin-sequence characteristics, and no differentiation was observed between malignant tumours of epithelial and mesenchymal origin. The major drawback of magnetic resonance is the poor demonstration of bone and calcification in the sinuses, so that in some patients the scans need to be augmented by computed tomography studies.

The role of intubation macro-dacryocystography in management of problems of the lacrimal system.

The Lloyd technique of dacryocystography has been described incorporating intubation, distension, macrographic and subtraction techniques. Excellent anatomic localization is possible. With this method, logical surgery may be planned.

CT of the paranasal sinuses: study of a control series in relation to endoscopic sinus surgery.

A control series of biplane CT scans of the paranasal sinuses, derived from patients examined for orbital tumours, is described. The scans were assessed for the presence of anatomical variants in the middle meatus, said to contribute to meatal stenosis, and for signs of asymptomatic infection revealed by the presence of clouding or mucosal thickening in the sinuses. Of the anatomical variants, only concha bullosa (pneumatisation of the middle turbinate) was associated with a high incidence of infection in the sinuses (85 per cent). Evidence of asymptomatic sinus infection was as high as 39 per cent overall, the highest incidence occurring in the ethmoid cells (28 per cent). Isolated ethmoid clouding on CT was observed in 15 per cent and is likely to be found in as many as one in seven of the adult population in the UK. It is concluded that in the majority of patients clouding confined to a few ethmoid cells shown on CT is without clinical significance. The evidence from the control series did not support the concept that most sinus infection starts in the middle meatus. The presence of a large reservoir of quiescent or chronic sinus infection in the control group suggests that in most instances sinusitis derives from a recrudescence of this pre-existing infection.

Diagnostic imaging of the nose and paranasal sinuses.

There are four principal modalities now used by the Radiologist to investigate the nose and paranasal sinuses. These are: plain X-ray, conventional tomography, computerised tomography (CT), and magnetic resonance (MR). Plain X-ray is the initial examination, and is used as a screening procedure before employing one of the tomographic techniques. Conventional pluridirectional tomography has now been superseded by CT scanning, which has the advantage of providing both good bone detail and soft tissue imaging. Since the introduction of magnetic resonance (MR), this technique has replaced CT as the optimum method of showing the extent of soft tissue tumour in the sinuses. The introduction of the paramagnetic contrast agent Gadolinium (Gd DTPA) has improved its accuracy. In the anterior fossa discrimination between cerebral oedema and tumour invasion is better shown, and in the sinuses tumour is more easily identified from retained secretion and inflamed mucosa. The best method currently available to show pathology in the nose and sinuses is a combination of GdMR and CT: the former to identify the soft tissues and the latter to show bone changes.

Subtraction magnetic resonance for tumours of the skull base and sinuses: a new imaging technique.

A new imaging technique is described, in which photographic subtraction as practised in angiography, is combined with Gadolinium enhanced Magnetic Resonance (GdMR) imaging and applied to the investigation of the paranasal sinuses and skull base. The densities on the subtraction image are dependent upon the blood supply of the tissues examined, thus producing a record of their vascularity: in effect a vasculogram. The method has proved to be technically feasible, and is advantageous in certain situations, particularly those in which the anatomy is complex as in the skull base or where normal structures have been distorted by previous surgery. The technique provides a more accurate record of tumour extent than that shown on unsubtracted GdMR scans.

CT of the paranasal sinuses and functional endoscopic surgery: a critical analysis of 100 symptomatic patients.

CT scans of 100 patients from the Rhinology Clinic at the Royal National Throat, Nose and Ear Hospital were reviewed in order to test the precepts forming the basis of functional endoscopic sinus surgery, especially as they relate to the radiological investigation. These were: (a) the site of origin of sinus infection, (b) The relevance of certain anatomical variants in the middle meatus to sinus infection and (c) The use of CT as the radiological method of diagnosis in all cases. Obstruction in the middle meatus and ostiomeatal complex was associated with an increased incidence of opacity in the sinuses but the primary site of disease was not established: the concept that sinus disease takes origin in the middle meatus was not proven. Anatomical variants in the middle meatus were not associated with an increase in sinus opacity and there was no evidence that these anomalies have any effect on sinus disease by causing middle meatal stenosis. The radiological assessment of patients with inflammatory naso-sinus disease should start with plain X-ray. CT is unnecessary as a routine examination. It should be reserved for the pre-operative assessment of patients for endoscopic surgery, its main function being to show important anatomical landmarks.

Radiological study of primary spontaneous CSF rhinorrhoea.

A radiological study of skull base anatomy was performed in patients presenting with primary spontaneous CSF rhinorrhoea. Radiology correctly identified the fistula site in 90 per cent of cases. Contrast CT imaging was found to be the most suitable technique for identifying the presence and site of CSF fistulae. However, pre-contrast bony dehiscences were identified in all patients leaking from the cribriform plate region. More significantly, all of these patients showed deviation of their crista galli, a radiological sign hitherto unreported. These findings support the theory that congenital bony dehiscence is the aetiological basis for this condition. The importance of radiology in the management of this condition is emphasized.