Amniotic fluid volume: Rapid MR-based assessment at 28-32 weeks gestation.

OBJECTIVES: This work evaluates rapid magnetic resonance projection hydrography (PH) based amniotic fluid volume (AFV) estimates against established routine ultrasound single deepest vertical pocket (SDVP) and amniotic fluid index (AFI) measurements, in utero at 28-32 weeks gestation. Manual multi-section planimetry (MSP) based measurement of AFV is used as a proxy reference standard. METHODS: Thirty-five women with a healthy singleton pregnancy (20-41 years) attending routine antenatal ultrasound were recruited. SDVP and AFI were measured using ultrasound, with same day MRI assessing AFV with PH and MSP. The relationships between the respective techniques were assessed using linear regression analysis and Bland-Altman method comparison statistics. RESULTS: When comparing estimated AFV, a highly significant relationship was observed between PH and the reference standard MSP (R(2) = 0.802, p < 0.001). For the US measurements, SDVP measurement related most closely to amniotic fluid volume, (R(2) = 0.470, p < 0.001), with AFI demonstrating a weaker relationship (R(2) = 0.208, p = 0.007). CONCLUSION: This study shows that rapid MRI based PH measurement is a better predictor of AFV, relating more closely to our proxy standard than established US techniques. Although larger validation studies across a range of gestational ages are required this approach could form part of MR fetal assessment, particularly where poly- or oligohydramnios is suspected. KEY POINTS: • MR projection hydrography can be used to estimate amniotic fluid volume. • MR projection hydrography relies on the T2w signal from amniotic fluid. • Amniotic fluid volume (AFV) is more accurately assessed than with ultrasound.

Post-mortem skeletal surveys in suspected non-accidental injury.

AIM: To evaluate potential differences between live (LSS) and post-mortem skeletal surveys (PMSS) in cases of non-accidental injury (NAI). MATERIALS AND METHODS: All skeletal surveys (SS) performed for suspected NAI over a 5 year period were retrospectively reviewed. Demographic details, injuries obtained, artefacts, and radiographic difficulties encountered during LSS and PMSS were recorded. RESULTS: Of 195 surveys performed, there were significantly fewer positive PMSS (11/128; 8.6%) than LSS (16/67; 23.8%), but no difference between the actual injuries encountered. Of those who had a positive SS, dead children were significantly younger (mean age 2.6 ± 3.4 months old) than live children (7.8 ± 6.9 months old; p < 0.05). Thirty-six percent of all contemporary digital radiographs contained artefacts, particularly in PMSS (599/1504; 39.8%) compared to LSS (269/904: 29.7%; p < 0.001), which were mostly patient identification labels (55.1 versus 21.6%; p < 0.001). PMSS demonstrated death-related radiographic complications in 10.6% of cases. CONCLUSION: Radiographic imaging in deceased children is not easy, and yields significant artefacts, which may hamper image interpretation. A technique for obtaining multiple views of a limb in fixed flexion deformity to maximize the diagnostic potential is described. Careful consideration of these factors would maximize the diagnostic yield in this unique patient population.

Nutcracker and SMA syndromes: What is the normal SMA angle in children?

OBJECTIVE: The nutcracker and superior mesenteric artery (SMA) syndromes are rare conditions where the left renal vein or duodenum may be compressed by an unusually acute angle between the SMA and aorta, although the normal angle in children is unknown. We measured the SMA angle to define the normal range in children. METHODS: We retrospectively measured SMA angles, left renal vein (LRV) distance, and duodenal distance (DD) in 205 consecutive pediatric abdominal CT. Total and visceral intra-abdominal fat at the level of the umbilicus were also assessed. RESULTS: Mean SMA angle was 45.6±19.6° (range 10.6-112.9°), mean LRV distance was 8.6±3.9mm (range 2.0-28.6mm) and mean DD was 11.3±4.8mm (range 3.6-35.3mm). There was a significant but weak correlation between %visceral fat volume (%VF) and SMA angle (R=0.30; p<0.001), LRV distance (R=0.37, p<0.001) and DD (R=0.32; p<0.001). CONCLUSION: There is a wide range of SMA angle, LRV and DD in normal children, which correlated weakly with visceral fat volume. Using a definition of SMA angle <25° would diagnose 9.3% of asymptomatic children with nutcracker syndrome, and using a DD definition of <8mm would diagnose 20% with SMA compression. Our findings suggest exercising caution when attributing these rare syndromes to an absolute SMA angle.

Minimally-invasive fetal autopsy using magnetic resonance imaging and percutaneous organ biopsies: clinical value and comparison to conventional autopsy.

OBJECTIVES: Autopsy is an important investigation following fetal death or termination for fetal abnormality. Postmortem magnetic resonance imaging (MRI) can provide macroscopic information of comparable quality to that of conventional autopsy in the event of perinatal death. It does not provide tissue for histological examination, which may limit the quality of counseling for recurrence risks and elucidation of the cause of death. We sought to examine the comparability and clinical value of a combination of postmortem MRI and percutaneous fetal organ biopsies (minimally invasive autopsy (MIA)) with conventional fetal autopsy. METHODS: Forty-four fetuses underwent postmortem MRI and attempted percutaneous biopsy (using surface landmarks) of major fetal organs (liver, lung, heart, spleen, kidney, adrenal and thymus) following fetal death or termination for abnormality, prior to conventional autopsy, which was considered the 'gold standard'. We compared significant findings of the two examinations for both diagnostic information and clinical significance. Ancillary investigations (such as radiographs and placental histology) were regarded as common to the two forms of autopsy. RESULTS: In 21 cases conventional autopsy provided superior diagnostic information to that of MIA. In two cases the MIA provided superior diagnostic information to that of conventional autopsy, when autolysis prevented detailed examination of the fetal brain. In the remaining 21 cases, conventional autopsy and MIA provided equivalent diagnostic information. With regard to clinical significance, however, in 32 (72.7%) cases, the MIA provided information of at least equivalent clinical significance to that of conventional autopsy. In no case did the addition of percutaneous biopsies reveal information of additional clinical significance. CONCLUSIONS: Although in some cases MRI may provide additional information, conventional perinatal autopsy remains the gold standard for the investigation of fetal death. The utility of adding percutaneous organ biopsies, without imaging guidance, to an MRI-based fetal autopsy remains unproven. Postmortem MRI, combined with ancillary investigations such as placental histology, external examination by a pathologist, cytogenetics and plain radiography provided information of equivalent clinical significance in the majority of cases.

The toddler refusing to weight-bear: a revised imaging guide from a case series.

BACKGROUND: The previously mobile child who refuses to walk or weight-bear is a common presentation to the accident and emergency department, for which there are a number of causes. One uncommon cause is discitis, an inflammatory process of the intervertebral disc, which is easily diagnosed with spinal magnetic resonance imaging (MRI). A case series of three patients is presented of non-weight-bearing children in whom there was a delay in making the diagnosis of lumbosacral discitis. None presented with back pain, spinal symptoms or abnormal neurological findings, and a full range of movement of both hips was found. METHODS: All patients underwent conventional radiography and ultrasound, but diagnoses were made on spinal MRI, with two patients undergoing bone scintigraphy before this. RESULTS: The mean delay was 15.6 days (range 13-20) from presentation at the hospital to MRI. All three patients made a good clinical recovery with intravenous antibiotics. CONCLUSION: These cases are presented in order to heighten the awareness of this disease entity and its imaging findings, and suggest new guidelines for the appropriate radiological investigations in this clinical setting.

Evaluation of image quality and radiation dose in adolescent thoracic imaging: 64-slice is preferable to 16-slice multislice CT.

There is a constant drive for radiology departments to acquire newer and improved CT machines in order to facilitate faster procedures and a greater repertoire of examinations. However, it is unclear whether the newer technology provides significantly improved image quality, or carries radiation dose implications for patients during everyday clinical practice. We assessed image quality and radiation dose in 15 children and young adults aged 9.3-19.5 years who underwent thoracic imaging on both 16-slice (16CT) and 64-slice (64CT) CT machines. Images were assessed for image quality on a visual analogue scale (1 = unacceptable; 5 = perfect) and preferred image set. All datasets were diagnostically acceptable (scores of 3 or more). The scores for 64CT datasets were significantly better than for 16CT datasets (mean scores of 4.5 and 4.0, respectively; p<0.05). The mean dose-length product (DLP) given was significantly higher during 16CT examinations at 152 mGy cm (effective dose, 2.1 mSv) than for 64CT examinations at 136 mGy cm (1.9 mSv; p<0.05). On average, 64CT examination DLPs were 16 mGy cm (or 9%) lower than the equivalent 16CT examination DLPs. In the context of childhood and adolescent thoracic CT imaging, and using the same software from the same manufacturers, 64CT examinations provide better image quality and give a lower effective dose than do 16CT examinations. If the choice were available, it would be pertinent to use 64CT for this patient group.

Feasibility of percutaneous organ biopsy as part of a minimally invasive perinatal autopsy.

To determine the feasibility of percutaneous fetal organ biopsies in the context of a 'minimally invasive' perinatal autopsy after stillbirth and termination for abnormality is the aim of this study. We assessed successful biopsy rate and the proportion adequate for histological examination in 30 fetuses undergoing organ sampling before autopsy. The relationship between gestational age, body weight, death-biopsy interval, operator experience and successful biopsy rate was investigated. Significant findings from conventional block histology were compared with corresponding percutaneous biopsies. Of 210 organ biopsies attempted from seven target organs, 107 were obtained, of which 94 were adequate for pathological comment. The median delivery-autopsy interval was 4 (range 2-11) days. Adequate samples were obtained from the lung in 86% cases (95% CI 68, 96%), liver 76% (95% CI 56, 90%) and less frequently for the myocardium, kidney, adrenal, thymus and spleen. There was no relationship between biopsy success and time to biopsy, gestational age, body weight and user experience. No histological abnormalities found at autopsy were diagnosed from needle biopsies. Although targeted percutaneous biopsies appear feasible for some organs, fewer than 50% of all biopsies are adequate for histological examination. This technique cannot be considered to provide useful clinical information as part of a 'minimally invasive' perinatal autopsy.

Use of a confidence scale in reporting postmortem fetal magnetic resonance imaging.

OBJECTIVES: Postmortem magnetic resonance imaging (MRI) may be an alternative to conventional autopsy. However, it is unclear how confident radiologists are in reporting such studies. We sought to determine the confidence with which radiologists report on various fetal organs by developing a scale to express their confidence of normality and abnormality, and to place this in the context of a pathological diagnosis of whether the organ was in fact normal or abnormal. METHODS: Thirty fetuses, aged 16-39 gestational weeks and weighing 61-3270 g, underwent postmortem MRI prior to conventional autopsy. MRI studies were reported by two radiologists with access to the clinical and sonographic history: a neuroradiologist, reporting head and neck, and a pediatric radiologist, reporting thorax, abdomen and pelvis. Radiologists used a scale (0 = definitely abnormal, 100 = definitely normal, 50 = unable to comment) to indicate their confidence of anatomical structures being normal or abnormal, using a checklist. Conventional autopsies were performed by pediatric pathologists blinded to the MRI findings, and these were considered the reference standard. RESULTS: Most normal fetal organs had high scores on postmortem MRI, with median confidence scores above 80. However, the atrioventricular valves, duodenum, bowel rotation and pancreas proved more difficult to assess, with median scores of 50, 60, 60 and 62.5, respectively. Abnormal cardiac atria and ventricles, kidneys, cerebral hemispheres and corpus callosum were always detected with high or moderate degrees of confidence (median scores of 2.5, 5, 0, 0 and 30 respectively). However, in two cases with abnormal cardiac outflow tracts, both cases scored 50. Kappa values, assessing agreement between MRI diagnoses of abnormality and autopsy, were high for the brain (0.83), moderate for the lungs (0.56) and fair for the heart (0.33). CONCLUSIONS: This scoring system represents an attempt to define the confidence of radiologists to report varying degrees of normality and abnormality following z ex-utero fetal MRI. While most fetal anatomy is clearly visualized on postmortem MRI, radiologists may lack confidence reporting such studies and there are particular problems with assessment of some cardiac and gastrointestinal structures, both normal and abnormal.

Ultrasound, CT and colonoscopy of colonic cancer.

Barium enema and colonoscopy are commonly used for the investigation of suspected colonic cancer. These techniques are relatively invasive and both the investigation and the preceding bowel preparation are demanding, particularly in the elderly. A prospective, blinded trial was conducted to compare ultrasound (US) and CT with colonoscopy. CT and colonoscopy were performed on 50 patients with symptoms suggesting colonic cancer. Both radiological investigations were performed prior to the bowel preparation for colonoscopy. US was performed without any preparation and oral contrast medium was the only preparation used for CT. Colonoscopy detected six cancers, all of which were diagnosed by both US and CT. In addition, US and CT diagnosed a further cancer not seen on colonoscopy due to an incomplete study. US had a sensitivity and specificity of 100% and CT a sensitivity of 100% and a specificity of 84%. US and CT were poor at diagnosing polyps. If the detection of polyps greater than 2 cm is included then US sensitivity falls to 67% and CT sensitivity falls to 89% and specificity rises to 88%. In conclusion, both US and CT are possible alternatives to colonoscopy in the investigation of symptomatic patients with suspected colonic cancer. The use of these techniques could markedly reduce the need for colonoscopy in this patient population with attendant cost savings. Non-invasive imaging has particular advantages in the elderly who cope poorly with both the bowel preparation and the procedure.

Clinical prediction of post-extubation radiological changes of the chest in newborn infants.

OBJECTIVE: Whether a chest radiograph should be performed routinely in all infants after extubation, or selectively only in those with clinical deterioration, is a controversy in neonatal unit practice. This study tested the hypothesis that most cases of post-extubation radiological deterioration in the lungs could be detected by clinical assessment. METHODS: A chest radiograph was performed at 8 h post-extubation in 100 episodes of extubation in 85 newborn infants ventilated for a variety of lung diseases. Each infant was assessed at the same time by a neonatologist blinded to the radiological findings, to determine whether a chest radiograph would have been requested based on clinical judgement. The infants were continuously monitored for their respiratory and oxygenation status before and after extubation. RESULTS: Compared to the pre-extubation chest radiographs, 23 of the 100 post-extubation chest radiographs showed either deterioration of the pre-existing lung pathologies or appearance of significant new pathologies. The clinicians' assessment failed to detect most of the deterioration, with a sensitivity of only 21.7%. Systematic analysis of the infants' clinical parameters showed that the development of significant intercostal/subcostal retraction, and an increase in inspired oxygen concentration by > or = 7% after extubation, were the best predictors of post-extubation radiological deterioration (sensitivity 82.6%, specificity 62.3%, positive predictive value 39.6%, and negative predictive value 92.3%). Serial blood gas in contrast had little predictive value. CONCLUSION: We conclude that most cases of radiological deterioration of the lungs after extubation are clinically predictable, provided the correct clinical criteria are used.

Sonographic features of Hashimoto thyroiditis in childhood.

Fifty-seven sonograms of 18 children with Hashimoto thyroiditis were retrospectively assessed. Thirty-three examinations (in 12 patients) showed thyroid glands which were more reflective than adjacent strap muscles, 22 studies (in eight patients) demonstrated glands of equal reflectivity and two examinations (in one child) depicted thyroid glands of lower reflectivity than muscle. The most frequent ultrasound appearance consisted of 2-5 mm echopenic lesions generally distributed throughout large poorly-defined hyperreflective glands. In serial examinations no correlation was found between laboratory indexes of thyroid status and sonographic findings.

Abdominal sonography in the evaluation of heterotaxy in children.

Heterotaxy is a rare congenital disorder characterised by abnormal viscero-vascular situs with either left or right isomerism that usually coincides with complex cardiac malformation. A precise diagnosis must be made for the selection of the most appropriate treatment. The diagnosis and evaluation of these conditions have been dependent on invasive studies such as angiocardiography, although more recently magnetic resonance imaging (MRI) has been advocated. In paediatric patients MRI is far from ideal because of the need for sedation and monitoring during the examination. The authors reviewed the modalities used in the evaluation of heterotaxy with emphasis on the use of ultrasonography, including pulse and colour flow Doppler imaging. A series of 14 children with heterotaxy is presented; ten with left abdominal isomerism (polysplenia) and four with right isomerism (asplenia). Results of abdominal sonography were compared with those of echo- and angiocardiography, surgery and autopsy. Of the ten children with left abdominal isomerism, two had no cardiac abnormalities. All those with right isomerism had a complex vitium. One patient with left abdominal isomerism proved to have right atrial isomerism. Some new reproducible patterns in viscero-vascular derangement are reported. The predictable patterns of left and right isomerism are outlined and atypical features discussed.

Demonstration of popliteal artery entrapment on leg muscle scintigraphy with 99mTc MIBI and single photon emission tomography.

Popliteal artery entrapment is difficult to diagnose even at surgery. Early diagnosis is important as the prognosis is better if detected before the onset of complications. There is no sensitive method for the evaluation of this condition. We describe three cases detected by a new technique using 99mTc methoxy isobutyl isonitrile (MIBI) with single photon emission tomography. The scintigraphic features of entrapment and the advantage of MIBI leg scintigraphy over other methods are discussed.

Hemoptysis: comparative study of the role of CT and fiberoptic bronchoscopy.

PURPOSE: A prospective study was performed to compare results of computed tomography (CT) and fiberoptic bronchoscopy in diagnosis of cancer in patients with hemoptysis. MATERIALS AND METHODS: Ninety-one patients (64 men, 27 women) with hemoptysis underwent thin-section CT and fiberoptic bronchoscopy. RESULTS: CT scans demonstrated all 27 tumors seen at bronchoscopy and an additional seven, five of which were beyond bronchoscopic range. In patients with normal chest radiographs, bronchial carcinoma was detected in 5% at both bronchoscopy and CT. In patients with abnormal findings on radiographs, bronchoscopy allowed both location and histologic diagnosis in 78% of carcinomas but was unreliable in locating peripheral tumors demonstrated at CT. CT was insensitive in demonstrating early mucosal abnormalities, bronchitis, squamous metaplasia, and a benign papilloma, all detected at bronchoscopy. CONCLUSION: The initial examination should be bronchoscopy when there is high clinical suspicion of carcinoma and relevant radiographic abnormality, and CT when strong clinical suspicion of carcinoma is not substantiated at bronchoscopy in patients with normal findings on chest radiographs.

Pictorial review: benign and malignant enlargement of the pterygo-masseteric muscle complex.

Seven cases of unilateral enlargement of the pterygoid and/or masseter muscles due to haemangioma (1), benign masseteric hypertrophy (2), rhabdomyosarcoma (2), leukaemic infiltration (1) and non-Hodgkin's lymphoma (1) are presented. The differential diagnosis of pterygo-masseteric muscle enlargement is outlined and the usefulness of computed tomography (CT) discussed.

Artifacts in the ascending aorta on computed tomography: another measure of aortic distensibility?

The appearance of the ascending aorta was studied in 53 patients undergoing computed tomography on a modern system capable of routine 1 second data acquisition times. Motion artifact caused a blurred aortic outline in 48 patients; the extent was objectively and subjectively assessed. The maximum and minimum cross-sectional aortic areas were measured at the margins of the blur. The area of the blur, expressed as a fraction of the minimum aortic cross-sectional area, decreased with age (P < 0.001) and was significantly smaller in the 13 patients with known cardiovascular problems (P < 0.05). These findings were substantiated by the subjective gradings which showed less marked artifacts amongst elderly patients (although this observation did not reach statistical significance). Artifacts were less prominent in 16 patients with evidence of aortic wall calcification, both on subjective grading (P < 0.05) and formal area measurements (P < 0.05). These observations lead us to believe our postulation that this artifact is an indicator of aortic distensibility and thus, indirectly, of cardiovascular status.

Delayed presentation of oesophageal perforation simulating intrathoracic malignancy.

We report two patients with silent oesophageal perforation. In neither patient was the diagnosis made preoperatively by the referring physicians and a history of swallowing difficulty was elicited in only one patient. The appearances on computed tomography were very similar in both patients: there was a soft tissue mass in the upper retro-oesophageal region with destruction of the underlying vertebral body.