Ultrasound in the investigation of the right iliac fossa mass .sx By F. C. Millard , FRCS , M. C. Collins , FRCR and R. J. Peck , FRCR .sx Abstract .sx Patients presenting with a right iliac fossa ( RIF ) mass are a diagnostic problem .sx The objective of this study was to assess the role of ultrasound ( US ) in their investigation .sx A prospective series of 50 patients presenting with a clinically suspected RIF mass was examined by US and the findings correlated with the final diagnosis .sx There was a positive finding in 34 patients ( 68%) .sx Ultrasound correctly identified the organ of origin in 33 ( 97% ) and was able to guide the patients' further management .sx In 12 cases no abnormality was found in the RIF , of which 11 had no positive findings at follow-up and one was shown to have an unrelated abnormality at laparotomy .sx In four cases the findings were due to normal variants .sx Ultrasound is the imaging modality of first choice in patients presenting with a RIF mass .sx Patients presenting with a right iliac fossa ( RIF ) mass are a clinical diagnostic puzzle .sx Frequently , these patients have a series of investigations including barium enema and intravenous urography , which are often inconclusive .sx When an RIF mass is palpable it should be demonstrable by ultrasound ( US ) and therefore it should be possible to assess its organ of origin , and give some idea of its nature .sx Conversely , a normal US may exclude a lesion and prevent further unnecessary imaging , particularly if involving ionizing radiation .sx It was decided to perform a prospective study to assess the role of US in the investigation of these patients , and to determine any US features of RIF masses which may help establish their nature .sx Method A prospective study of 50 consecutive patients , presenting with the clinical diagnosis of an RIF mass and referred for US at the Royal Hallamshire Hospital , was carried out between January and August 1989 .sx Their ages ranged from 18 to 94 years ( mean 61 years) .sx Thirty-six were female and 14 male .sx The US was performed by a consultant radiologist using an ATL Ultramark 4 scanner with 3 MHz and 5 MHz sector transducers .sx A full abdominal scan was also performed routinely .sx The findings were confirmed by further imaging , laparotomy or in a few cases clinical follow-up .sx Results Thirty-four patients ( 68% ) were shown to have a lesion corresponding to the palpable RIF mass .sx In four patients the mass was due to a normal variant ( two - low lying kidney , two - Riedel's lobe ) , and in 12 no mass was visualized in the RIF .sx Of the 34 masses , US correctly identified the organ of origin in 33 .sx Eighteen of these were gastro-intestinal and the pathology was correctly suggested in 14 ( Table I) .sx Seven masses were arising from the genito-urinary tract , and US was correct in all seven ( Table II) .sx In a further nine patients , the mass arose from another organ system , and US made the correct diagnosis in seven ( Table III) .sx tables&captions .sx Of all the cases studied , the site of origin was wrongly suggested by US in only one .sx This was a 71-year-old female patient on anti-coagulant therapy , who presented sic !sx with lower abdominal pain , constipation , and a tender RIF mass .sx Clinical assessment suggested a complicated ovarian cyst .sx Ultrasound showed a complex mixed-echo mass anterior to the bladder .sx The appearances were difficult to interpret , and bowel malignancy was suggested .sx At laparotomy , however , an extensive rectus sheath haematoma was found .sx In the 12 patients in whom no mass was found at US , six underwent no further imaging .sx Of the remainder , five had a barium enema , of whom two also had a small bowl enema .sx No further pathology was demonstrated .sx One patient had the clinical picture of large bowel obstruction , and at laparotomy was found to have a carcinoma of the transverse colon and no actual mass in the RIF .sx Of the four patients in whom US found an anatomically normal variant of kidney or liver , two had no further imaging and two had a barium enema .sx table&caption .sx As far as can be determined , therefore , of the 12 patients with 'negative' US there were no false negatives ( excluding the one patient who later was found to have a carcinoma of the transverse colon) .sx Discussion In any patient with a palpable RIF mass , we felt US should be the primary investigation .sx This suggestion was also made in a recently published retrospective study of US in the palpable abdominal mass ( Barker & Lindsell , 1990) .sx A normal US may exclude a lesion and prevent further unnecessary imaging .sx Our study confirmed this , US being highly specific ( 100% ) in excluding the presence of an RIF mass ( Table IV) .sx Equally , our study found US to be highly sensitive ( 100% ) in correctly identifying patients with an RIF mass ( Table IV) .sx We have found US to be highly accurate in identifying the organ of origin of the mass ( 97% ) as compared with clinical assessment ( 76%) .sx Ultrasound has always been thought to be of limited value in evaluating bowel problems , but gradually it is being shown to have much value in this area ( Gholkar & Khan , 1989) .sx The US features of appendicitis ( Puylaert , 1986 ; Jeffrey et al , 1988 ) , Crohn's disease ( Sonnenburg et al. 1983 ) and Campylobacter enteritis ( Puylaert et al , 1988 ) have all recently been described .sx Some ultrasonologists feel that a general review of the abdomen during an ultrasound examination can provide significant useful information , particularly in the detection of occult neoplasms ( Price & Metreweli , 1988) .sx table&caption .sx The correct pathological diagnosis was made by US in 82% of cases .sx Although we were able to determine bowel as the cause of the mass in all the 19 cases in which this proved so , it was more difficult to differentiate neoplastic from inflammatory lesions .sx In conclusion , this prospective study found US , in experienced hands , to be accurate in assessing RIF masses , with the advantage that it is non-invasive and does not involve the use of ionizing radiation .sx It should be the first investigation of choice in these patients .sx A new phantom for mammography .sx By J. Law , PhD .sx Abstract .sx A new mammography phantom from Du Pont is described .sx It has a wider range of types of detail than in previous phantoms , including some which closely simulate breast tissues .sx Experience of its use , and comparisons with an earlier ( 'Barts' ) phantom , are reported .sx The Du Pont phantom appears to have greater sensitivity to changes in tube kV and focal spot size , and better discrimination between different film-screen combinations and between films from different breast screening centres .sx The importance of a suitable phantom , or test object , in monitoring and maintaining image quality in mammography is well known ( see for example Pritchard , 1988) .sx Such a phantom should contain details which mimic those which a radiologist looks for in clinical mammograms , and may also contain means for assessing limiting contrast and resolution .sx These two approaches are quite distinct , since many clinical details depend on a combination of both contrast discrimination and resolution .sx If the latter are assessed separately , it is not always a simple matter to combine the results to give a single measurement with an obvious relationship to the radiologist's needs .sx It is even more important that films of a phantom show clear differences if tube kV , focal spot size , or film/screen/processing characteristics change , especially since these may drift gradually .sx In screening mammography in particular , a useful phantom should be able to demonstrate such drifts before they become apparent in clinical mammograms .sx ( Even if a phantom does not do this , it may still have a role in identifying the origins of such drifts .sx ) .sx One phantom which adopts the first approach is that described by White and Tucker ( 1980 ) and sometimes called the 'Barts' phantom .sx This has been extensively used in a limited number of UK centres and found very valuable in at least some .sx However , it was difficult to construct , was never available commercially , and is no longer obtainable .sx It is also only moderately sensitive to changes in kV ( Law et al , 1989 ) and , at least for contact films , shows little sensitivity to changes in focal spot size .sx A more sensitive replacement has been needed for some time , but until very recently only one other phantom has shown any clearly demonstrable improvement , and some have failed to match it .sx That exception was the Wisconsin randomized phantom , which is too time consuming for routine use .sx This paper describes results obtained from a new phantom with a variety of types of detail , marketed by Du Pont .sx It appears to have most of the features outlined above .sx Description of phantom details .sx The details are contained within a 'black box' measuring approximately 10cm x 8cm x 2cm .sx This can be placed in various ways within an assembly of different sized pieces of Perspex , which all together simulate a compressed breast of average size .sx The details are shown in Fig. 1 .sx They include various objects with a range of contrasts , which mimic clinical mammographic features and which lend themselves to quantitative scoring , plus seven line bar patterns in two directions at right angles , from 8 to 20 lp/mm at low contrast , in steps of 2 lp/mm , which can also be counted to give a resolution score .sx In addition , there is a range of simulated tissues and structures , much more like breast tissue than any of the other features , but which are difficult to score except qualitatively or on a scale of ( say ) 1 to 3 .sx Lastly , over small areas the line bar patterns at right angles to each other overlap to give an indication of point resolution .sx The objects having a range of contrasts are of four kinds , and each is provided in five decreasing sizes and contrasts .sx These are :sx ( a ) Al 2 O 3 specks from 320 to 83 mu m which mimic microcalcifications ; .sx ( b ) plastic wires from 0.8 to 0.3 mm which mimic fibrous structures ; .sx ( c ) carbohydrate or amino-acid spheres from 1.2 to 0.35 mm ; .sx ( d ) discs containing 0.8 mm diameter holes , arranged to form the single digits 7 , 5 , 4 , 3 and 2 , where each digit indicates the depth of the holes .sx The simulated breast tissues are provided in three clusters of four each , which have very low , low , and normal absorption .sx Many also contain random micro - calcifications .sx There is also a single sample about 2cm in diameter representing the appearance of 'dense breast' , and some small fine structures said to represent lymph nodes .sx Methods of use of phantom .sx The arrangement recommended by the manufacturers has been used to obtain the results which follow ( Fig. 2) .sx One piece of Perspex , 12cm x 12cm and 3cm thick , is placed directly on the grid cover at the patient side , and with the 10cm x 8cm 'black box' on top of this .sx The 4cm space to one side of the box is partly filled by another Perspex piece , 12cm x 3cm x 1cm , and a further Perspex piece 12cm x 12cm x 1cm is placed above this and the black box .sx Thus the total attenuation is about 5cm Perspex .sx Behind this assembly , i.e. away from the patient , a Perspex step wedge can be placed , transverse to the anode cathode direction now normal in mammographic tubes .sx This wedge has eight steps from 5 to 40mm , and may be placed on top of another Perspex piece , 12cm x 3cm x 1cm , if desired .sx Lastly , the compression plate is lowered onto the whole assembly .sx figure&caption .sx To 'score' the films , i.e. to obtain a numerical figure of merit with some relationship to imagine quality , the manufacturers make no recommendations and numerous methods might be derived .sx To obtain the results reported here , the following method was adopted .sx For the four types of feature ( a ) to ( d ) above , each of the five sizes was given one point if it could be seen quite clearly , with edges appearing sharp to the eye , and half a point if some features of the type concerned were unambiguously visible but less clear .sx Doubtful appearances were given no score .sx This scoring was helped initially by a radiograph of the 'black box' with no Perspex or other scattering material adjacent .sx Radiologists' binocular viewers were always used to cut out surrounding glare .sx