Developments in imaging. An historical review.

Following the discovery of X-rays by Roentgen in 1895, it was 70 years later that the specialty of imaging really took off, with ultrasound, CT, Nuclear medicine, and MRI now an integral part of all large departments. The recent progress has been accelerated by advances in computer technology which aided the development of imaging techniques that do not use ionising radiation. Some imaging techniques are replacing other more hazardous diagnostic procedures, (e.g. MRCP v ERCP, and MRA v catheter angiography) while some are able to provide almost perfect anatomical detail e.g. brain MRI. Techniques using radioisotopes provide more functional information which can be used to complement the morphological studies. We have witnessed the birth and maturation of Interventional Radiology. This is a highly skilled subspecialty enabling some surgical procedures to be replaced by minimally invasive methods using image guidance. These range from simple drainage procedures and guided biopsies to complex aortic bifurcation stent graft insertions. The potential for digital storage of all images is already established and the filmless radiology department in the more developed countries could be the norm by 2020.

Comparison of ultrasound with fluoroscopy in the assessment of suspected hemidiaphragmatic movement abnormality.

A comparative study of quantitative hemidiaphragmatic ultrasound with fluoroscopy was undertaken in 30 patients referred for investigation of suspected hemidiaphragmatic movement abnormality. The aim of this study was to determine whether assessment with ultrasound or fluoroscopy differed, and which technique appeared more suitable in the investigation of hemidiaphragmatic movement disorder. There were four technical failures using fluoroscopy (13%), compared with none using ultrasound. Using the normal ranges of right to left ratio of maximal excursion (0.5-2.0 for fluoroscopy and 0.5-1.6 for ultrasound) there was concordance in 21 out of 26 (81%) patients. All cases of abnormality on fluoroscopy were seen on ultrasound. Four of the discordant cases had excursions on the lesser side in the normal range on ultrasound suggesting a milder movement abnormality detected by ultrasound than by fluoroscopy. Sniff testing conferred no advantage over quantitative testing. Ultrasound has technical, qualitative and quantitative advantages over fluoroscopy and should be the method of choice in the investigation of suspected hemidiaphragmatic movement abnormality.

Ultrasound assessment of normal hemidiaphragmatic movement: relation to inspiratory volume.

BACKGROUND: Traditionally the radiological assessment of diaphragmatic movement has relied on fluoroscopy. Ultrasound scanning has recently been shown to be a sensitive and reproducible method of assessing hemidiaphragmatic movement in normal subjects. A study was undertaken to examine how movement of the diaphragm measured by ultrasound scanning relates to inspired lung volumes measured by spirometric testing. METHODS: Ultrasound examinations were performed on 14 normal volunteers using a 3.5 MHz sector transducer (Acuson 128). A fixed skin position on each lateral chest wall between the anterior clavicular and midaxillary line was selected symmetrically to obtain a longitudinal plane of each hemidiaphragm including the maximal renal bipolar length, allowing identification of the adjacent posterior aspect of the diaphragm. Craniocaudal excursions of the posterior part of each hemidiaphragm on successive respiratory cycles were recorded on videotape and compared with spirometric measurements recorded simultaneously on a water bath spirometer. Measurements were made in the sitting and supine position and were repeated on a separate occasion (at least two weeks apart) in 10 subjects by the same operator to assess reproducibility. RESULTS: The relation between inspired volume and hemidiaphragmatic movement was found to be linear. The gradient of these observed linear relations (hemidiaphragmatic excursion (mm)/inspired volume (1)) was calculated and their distribution for each hemidiaphragm followed a normal distribution irrespective of position. The 95% confidence limits of the right to left ratio of these gradients in the supine position were 0.53 and 1.7. Change of posture from the supine to the sitting position reduced the gradient. The technique had acceptable reproducibility with coefficients of variation for the supine position of 7.5% and 11.7% for right and left hemidiaphragm respectively. CONCLUSION: Ultrasound scanning is a simple, non-invasive and reproducible means of assessing hemidiaphragmatic movement, yielding quantitative information which relates to inspired lung volumes.

Overnight clonidine suppression test in the diagnosis and exclusion of pheochromocytoma.

In a prospective study designed to differentiate pheochromocytoma from other forms of hypertension, urinary catecholamines were measured after sleep and clonidine administration in 12 patients with pheochromocytoma, 19 hypertensive patients in whom pheochromocytoma was suspected but later excluded, and 31 hypertensive patients in whom pheochromocytoma was never suspected. The test correctly identified all 12 patients in whom pheochromocytoma was present. Four of these had equivocal plasma levels of both norepinephrine and epinephrine, suggesting that overnight clonidine suppression may be of particular value when tumor secretion is intermittent or low. When pheochromocytoma was not present, urinary norepinephrine and epinephrine levels were suppressed below 60 and 20 nmol/mmol creatinine, respectively, after sleep and clonidine, the two in combination giving better suppression than sleep alone. Since urinary catecholamines can be determined relatively easily by high-pressure liquid chromatography with electrochemical detection, this test may be more widely applicable than suppression tests based on plasma measurements.

Simultaneous computed tomography and sialography of the parotid and submandibular glands.

A technique of simultaneous computed tomography and sialography of the parotid and submandibular glands is described and the examination of 14 patients reported. Tumours were diagnosed in six cases and in the remaining eight cases inflammatory lesions were found. Sialographic enhancement offered definite advantages in localisation of lesions and examination of the tumour-normal tissue interface compared with either C.T. or sialography alone.

Bilateral parotid gland aplasia.

Bilateral parotid gland aplasia is a cause of xerostomia. A case is presented in which the clinical diagnosis was confirmed with the use of 99mTcO-4 salivary gland scintiscanning and computerised tomography. The literature of this rare condition is reviewed and significance to the patient discussed.

The localisation of parathyroid tumours--a comparison of computed tomography with cervical vein hormone assay.

Computed tomography has been employed for the localisation of parathyroid tissue in 26 patients with primary hyperparathyroidism. In 14 of these selective venous catheter studies with parathyroid hormone assay were also undertaken. Computed tomography proved unreliable, identifying only 39 per cent whereas the cervical venous hormone assay studies localised 69 per cent of lesions correctly--a figure which is in agreement with several other groups. On balance our results suggest that neither technique should be routinely employed pre-operatively but that, following unsuccessful parathyroid surgery, the most useful localisation technique remains venous hormone assay.