A comprehensive SWOT audit of the role of the biomedical physicist in the education of healthcare professionals in Europe

Although biomedical physicists provide educational services to the healthcare professions in the majority of universities in Europe, their precise role with respect to the education of the healthcare professions has not been studied systematically. To address this issue we are conducting a research project to produce a strategic development model for the role using the well-established SWOT (Strengths, Weaknesses, Opportunities, Threats) methodology. SWOT based strategic planning is a two-step process: one first carries out a SWOT position audit and then uses the identified SWOT themes to construct the strategic development model. This paper reports the results of a SWOT audit for the role of the biomedical physicist in the education of the healthcare professions in Europe. Internal Strengths and Weaknesses of the role were identified through a qualitative survey of biomedical physics departments and biomedical physics curricula delivered to healthcare professionals across Europe. External environmental Opportunities and Threats were identified through a systematic survey of the healthcare, healthcare professional education and higher education literature and categorized under standard PEST (Political, Economic, Social-Psychological, Technological-Scientific) categories. The paper includes an appendix of terminology. Defined terms are marked with an asterisk in the text.

The debate on the use of linear no threshold for assessing the effects of low doses

From December 2004 to July 2005, three reports on the effects of low doses of ionising radiation were released: ICRP (2004), the joint report of the French Academies of Science and Medicine (Tubiana et al 2005), and a report from the American Academy of Sciences (BEIR VII 2005). These reports quote the same recent articles on the biological effects of low doses, yet their conclusions diverge. The French report concludes that recent biological data show that the efficacy of defense mechanisms is modulated by dose and dose rate and that linear no threshold (LNT) is no longer plausible. The ICRP and the BEIR VII reports recognise that there are biologic arguments against LNT but feel that there are not sufficient biological proofs against it to change risk assessment methodology and subsequent regulatory policy based on LNT. They point out the remaining uncertainties and the lack of mechanistic explanations of phenomena such as low dose hyperlethality or the adaptive response. In this context, a critical analysis of the available data is necessary. The epidemiological data and the experimental data challenge the validity of the LNT hypothesis for assessing the carcinogenic effect of low doses, but do not allow its exclusion. Therefore, the main criteria for selecting the most reliable dose-effect relationship from a scientific point of view should be based on biological data. Their analysis should help one to understand the current controversy.

Recent reports on the effect of low doses of ionizing radiation and its dose-effect relationship

Recently, the risk associated with low doses of ionizing radiation has gained new interest. Here, we analyze and discuss the major differences between two reports recently published on this issue; the report of the French Academy of Sciences and of the French Academy of Medicine published in March 2005, and the BEIR VII-Phase 2 Report of the American National Academy of Sciences published as a preliminary version in July 2005. The conclusion of the French Report is that the linear no-threshold relationship (LNT) may greatly overestimate the carcinogenic effect of low doses (<100 mSv) and even more that of very low doses (<10 mSv), such as those delivered during X-ray examinations. Conversely, the conclusion of the BEIR VII report is that LNT should be used for assessing the detrimental effects of these low and very low doses. The causes of these diverging conclusions should be carefully examined. They seem to be mostly associated with the interpretation of recent biological data. The point of view of the French Report is that these recent data are incompatible with the postulate on which LNT is implicitly based, namely the constancy of the carcinogenic effect per unit dose, irrespective of dose and dose rate.

Usefulness of fine needle aspiration cytology in the diagnosis of loco-regional recurrence of differentiated thyroid carcinoma

AIM

The aim of our study was to define the usefulness of fine needle aspiration cytology (FNAC) in the assessment of loco-regional recurrence of differentiated thyroid carcinoma (DTC).

METHODS

Among 1182 consecutive patients treated and followed for DTC from 1992 to 2001, we retrospectively analysed 65 FNAC results of patients presenting a suspicion of loco-regional recurrence. Recurrences were proved at histology in 35 cases and by cervical radioiodine uptake on post-therapeutic WBS (whole body scan) in nine cases.

RESULTS

Among the 44 recurrences, FNAC results were malignant, benign and unsatisfactory in 33, two and nine cases, respectively. For the diagnosis of malignancy, FNAC sensitivity was 94%, specificity 100%, positive predictive value 100% and negative predictive value 87%. In the 35 cases where divergent results between diagnostic WBS (37-111MBq (131)I) and Tg level were observed, FNAC assessed the final status in 22 cases (malignant and benign in 17 and five cases, respectively). Of the 12 non-functioning and non-secreting lesions, FNAC diagnosed malignancy in four of the five malignant cases and ruled out malignancy in all seven benign lesions.

CONCLUSION

These results outline the interest of FNAC in the assessment of loco-regional recurrences of DTC, especially when classical follow-up tools such as WBS and/or Tg level are unable to detect the recurrences.

[Analytical aspects of the semiquantitative determination of urinary iodine using ferroin: value of rapid screening for iodine deficiency or excess]

Iodine is an essential element for thyroid hormone synthesis. Iodine disorders induced biological and/to clinical expression of thyroid dysfunction. Inappropriate iodine intake (by default or by excess) is worrying in terms of public health in France regarding the iodine deficiency and the frequency of iatrogen iodine overloads. Urinary iodine determination which generally implicates the use of a cerimetric method, is an useful tool to evaluate iodine intakes. In this study, we described the analytical aspects of a semiquantitative method of urinary iodine using a redox indicator, ferroin. This method allows the screening of iodine excess or deficiency in a short time (< 3 hours) with a good specificity and sensitivity. Since this assay does not require specific apparatus, it could be easily developed in clinical chemistry laboratories for the detection of inappropriate iodine intakes, and could be useful for prevention programs of iodine deficiency.

Survival and therapeutic modalities in patients with bone metastases of differentiated thyroid carcinomas

Data for patients with bone metastases (BMs) of differentiated thyroid carcinoma (DTC) were retrospectively studied to identify factors associated with survival. We especially studied the impact of therapies. Among the 1977 patients followed for DTC in our department from 1958 to 1999, 109 (77 females and 32 males; age range, 20--87 yr) presented BMS: All patients except 1 underwent total thyroidectomy, followed by radioiodine therapy (> or =3.7 gigabecquerels) in 95 cases. Survival rates at 5 and 10 yr were 41% and 15%, respectively. Univariate analyses indicated that a young age at BM discovery (P < 0.005) and the discovery of BM as a revealing symptom of DTC (P < 0.05) were features significantly associated with improved survival as well as radioiodine therapy (P < 10(-4)) and BM complete surgery (P < 0.02). Using multivariate analysis, the detection of BMs as a revealing symptom of thyroid carcinoma (P < 0.0005), the absence of metastasis appearance in other organs than bones during the follow-up (P < 0.03), the cumulative dose of radioiodine therapy (P < 0.0001), and complete BM surgery in young patients (P < 0.04) appeared as independent prognostic features associated with an improved survival.

Iodine kinetics and effectiveness of stable iodine prophylaxis after intake of radioactive iodine: a review

Ingestion of potassium iodide (KI) offers effective protection against irradiation of the thyroid after accidental exposure to radioactive iodine. This prophylaxis aims at rapidly obtaining maximal thyroid protection without adverse effects. This article reviews studies on iodine kinetics in humans and on the efficacy of KI in protecting the thyroid. In adults with normal thyroid function, ingestion of 100 mg of iodide just before exposure to radioactive iodine blocks at least 95% of the thyroid dose. If exposure persists after iodide ingestion (100 mg), the percentage of averted dose may decrease significantly. Daily ingestion of a dose of 15 mg of KI would then maintain the thyroid blockade at a level above 90%. The efficacy of iodide and the occurrence of antithyroid effects also depend on external and individual factors such as dietary iodine intake, thyroid function, and age. The KI dosage regimen should be adjusted for age at exposure. For the fetus, the newborn, children, and adolescents, the risk of radiation-induced thyroid cancer in case of accidental exposure to radioactive iodine justifies KI prophylaxis, despite the risk of hypothyroidism, especially in newborns. For the elderly, the benefits of KI may be lower than the risk of iodine-induced hyperthyroidism.

Absolute activity quantitation in simultaneous 123I/99mTc brain SPECT

Dual-isotope imaging can allow simultaneous assessment of brain perfusion using a 99mTc-labeled tracer and neurotransmission using an 123I-labeled tracer. However, the images are affected by scatter, cross talk, attenuation, distance-dependent collimator response (DCR), and partial-volume effect. We determined the accuracy and precision of activity quantitation in simulated normal and pathologic studies of simultaneous 123I/99mTc brain SPECT when compensating for all degrading phenomena.

METHODS

Monte Carlo simulations were performed using the Zubal brain phantom. Contamination caused by high-energy 123I decay photons was incorporated. Twenty-four 99mTc and 123I activity distributions were simulated on the basis of normal and pathologic patient activity distributions. Cross talk and scatter were corrected using a new method based on a multilayer perceptron artificial neural network (ANN), as well as by the asymmetric window (AW) approach; for comparison, unscattered (U) photons of 99mTc and 123I were recorded. Nonuniform attenuation and DCR were modeled in an iterative ordered-subset expectation maximization (OSEM) algorithm. Mean percentage biases and SDs over the 12 normal and 12 pathologic simulated studies were computed for each structure with respect to the known activity distributions.

RESULTS

For 123I, AW + OSEM yielded a bias of 7% in the cerebellum, 21% in the frontal cortex, and 36% in the corpus callosum in the simulated normal population. The bias was increased significantly in the striata of simulated pathologic studies (P < 0.05). The bias associated with ANN was significantly lower (<9% in these brain structures, P < 0.05). For 99mTc with AW + OSEM, the bias was 60% in the corpus callosum, 36% in the striata, and 18%-22% in the cortical lobes in the simulated normal population. This bias was <11% in all brain structures with ANN. In the simulated pathologic population, the bias associated with AW increased significantly in the cortical lobes to 55% (P < 0.05), although it did not change significantly with ANN.

CONCLUSION

The accuracy and variability over simulated normal and pathologic studies of both 99mTc and 123I activity estimates were very close with ANN to those obtained with U + OSEM. ANN + OSEM is a promising approach for absolute activity quantitation in simultaneous 99mTc/123I SPECT.

Post-Chernobyl thyroid carcinoma in children

The dramatic increase in childhood thyroid carcinoma observed in Belarus and Ukraine as early as 4 years after the Chernobyl nuclear accident, is well recognized as being a consequence of exposure to radioactive iodine fallout. Uncertainties persist concerning the contamination and the dosimetric data. Thyroid nodule, cervical lymph nodes or systematic ultrasound thyroid screening in exposed children led to the diagnosis. The carcinomas affected younger subjects, were less influenced by gender, and were more aggressive at clinical and histological presentation than in the case with naturally occurring carcinoma. Total thyroidectomy and radioiodine treatment remain the treatment of choice. The prognosis is good but further studies are needed to evaluate the prognosis of children presenting with pulmonary metastasis. The project of the Newly Independent States Chernobyl Tissue Bank will facilitate molecular genetic research into this important public health issue. Nevertheless, clinicians must keep in mind the simplicity and the effectiveness of iodine prophylaxis.

Pulmonary blood flow distribution in stage 1 chronic obstructive pulmonary disease

We investigated the hypothesis that lung blood flow distribution is modified in stage 1 chronic obstructive pulmonary disease (COPD). We compared patients with stage 1 COPD (n = 11) with restrictive patients with comparable blood gases (n = 7), to patients with low cardiac index with normal lungs (n = 11) and to control subjects (n = 11). Distribution of transit time (DTT) was computed by deconvolution from first pass radioactivity curves (albumin (99m)Tc) reconstructed from right and left ventricular regions of interest. Distribution descriptors, mean transit time (p < 0.05), standard deviation (p < 0.001), relative dispersion (p < 0.001), and kurtosis (p < 0.001) differed between groups (ANOVA). Cardiac index was the same in COPD and low CI groups but lower compared with normal subjects (p < 0.05). After normalization for cardiac output, the DTT of patients with COPD remained different from low CI and restrictive patients (p < 0.001). Therefore changes in DTT in patients with COPD compared with patients without COPD could not be explained on the basis of difference in cardiac output. Because P(O(2)), PC(O(2)), and pH were similar in COPD and restrictive groups, difference in distribution could not be explained either on the basis of blood gas data. We conclude that changes in DTT occurs in stage 1 COPD and cannot be explained by hypoxemia, hypercapnia, or acidosis alone but must relate to other structural or regulatory responses.

[Thyroid cancer in patients with hyperthyroidism]

OBJECTIVE

The prevalence of thyroid carcinoma in hyperthyroidism remains controversial. The aim of this retrospective study was to evaluate prevalence.

PATIENTS AND METHODS

The prevalence of thyroid carcinoma was studied in 861 patients operated for clinical or infraclinical hyperthyroidism between 1992 and 1999. One hundred and fifty patients had a hot nodule, 13 of them with an associated goiter. Four hundred five patients had Graves' disease and 306 had a multinodular goiter. Multiple sections were made in all surgical specimens for pathology study.

RESULTS

Prevalence in solitary nodules was 1.45%. For Graves' disease patients, it was 4.1%. Prevalence among patients with multinodular goiter was 4.9%. Among the cancers, 83% were microcarcinoma. Parathyroid morbidity after subtotal and total thyroidectomy was 0.56% and recurrent hyperthyroidism occurred in 1.6%.

CONCLUSIONS

These findings are grossly identical to those observed in simple, nontoxic diffuse multinodular goiter. It would therefore be difficult to incriminate hyperthyroidism as playing a causal role in the development of thyroid cancer. These results do however provide an argument favoring total or near total thyroidectomy when surgery is performed in patients with hyperthyroidism.

Fetal biometric parameters, twin type and birth weight difference. A longitudinal study

OBJECTIVE

To examine the relationship between twin type, divided by zygosity, chorionicity, and birth weight difference [more or less than 15% intertwin weight difference at delivery] on fetal biometric measurements, including biparietal diameter, transverse abdominal diameter, head and abdominal circumferences (AC) and head and abdominal areas, femur length (FL), transverse cerebellar diameter, cerebellar circumference and cerebellar area at 18, 23, 28 and 32 weeks of gestational age.

STUDY DESIGN

A prospective and longitudinal study was done on 75 twin pairs that did not present the twin-twin transfusion syndrome (150 fetuses) divided into birth weight difference group I (<15%) and group II (>/=15%). The twin pairs were divided into three groups: dizygotic, monochorionic, and dichorionic-monozygotic. In each group the differences in various ultrasound indices were evaluated in reference to discordant growth or concordant growth.

RESULTS

In our sample, there were no monozygotic twin pairs with dichorionic placentation with a birth weight difference of more than 15%. Significant associations of group and gestational age were found in dizygotic and monochorionic twins. Intrapair differences were significantly higher in group II (>/=15%) than in group I (<15%) for all fetal parameters studied except for AC, abdominal area and all cerebellar parameters. The value of these discrepancies increased according to gestational age except for FL. Significant interactions between group and zygosity type indicated that intrapair FL differences were more associated with group in monochorionic twins, whereas intrapair transverse cerebellar diameter differences were more associated with group in dizygotic twins.

CONCLUSION

Our data show that most fetal biometric parameters are associated with birth weight discordancy. Abdominal area could be a relevant marker for twins with obstetric complications. Note that this is the first research that has studied a twin sample divided by both twin type and birth weight group.

Secondary thyroidectomy in patients with prior thyroid surgery for benign disease: a study of 203 cases

BACKGROUND

The goal of this study was to evaluate the complication rate of secondary thyroidectomy in patients with prior thyroid surgery for benign disease.

METHODS

Over an 8-year period, 203 thyroid reoperations were performed on 202 patients. All information relating to operative procedures, pathology, and complications was recorded prospectively.

RESULTS

There were 24 men and 178 women with a mean age of 52 years. Prior surgery was unilateral in 136 cases (67%) and bilateral in 67 cases (33%), and 14 patients (6.9%) had more than 1 previous thyroid operation. For euthyroid or pretoxic recurrent nodular goiter, 190 reoperations were performed and 13 reoperations were performed for recurrent thyrotoxicosis. Twenty-three cancers were found in a specimen (11.4%). Completion thyroidectomy was done in 143 patients. Postoperative complications occurred in 21 patients (10.4%): recurrent laryngeal nerve palsy (7 patients), hypocalcemia (8 patients), hematoma requiring surgical evacuation (5 patients), and wound infection (1 patient). Complications remained permanent in 4 patients (2%).

CONCLUSIONS

The permanent complication rate is higher in thyroid reoperations than in primary thyroid operations. However, we believe that this 2% rate is low enough to allow reoperation whenever it is necessary, provided precise operative rules are respected.

Twin differences and similarities of birthweight and term in the French Romulus population

This study was performed to examine the main characteristics of the French Romulus twin population: zygosity, chorionicity, sex, term and birthweight. A sample of 104 pairs of twins was distinguished by zygosity, chorionicity and sex, and divided into concordant and discordant birthweight groups. Fifty-three % (n = 55) of the fetus pairs studied were born at "ideal term" (35-38 weeks), and 25% (n = 26) were delivered at "preterm" (28-34 weeks). The very preterm (< 28 weeks), and "postterm" (> 38 weeks) represented altogether 22% (n = 23) of the sample. Of the 104 twin pairs, 68% (n = 71) differ by less than 15% in birthweight, and 32% (n = 33) have a birthweight difference higher than 15%. In dizygotic (DZ) pairs females had more tendency to be in the discordant group (p = 0.01) while in monochorionic-monozygotic (MC-MZ) pairs males were more discordant (p = 0.07). We found a significant interaction between sex and zygosity type (p = 0.02). Males had a birthweight difference significantly weaker than that of females in dichorionic-monozygotic (DC-MZ) and DZ twins whereas it was higher than that of females in MC-MZ twins. There were no MZ twin pairs with DC placentation over than 15% birthweight difference. Log linear analysis demonstrated a three-way interaction (p < 0.05) between term type, zygosity type and hypotrophy. Our data indicate that in the group of twins born between 35 and 38 weeks' gestation the crucial question still remains unsettled on how term and birthweight are related to zygotism and/or chorionicity.

[What is the contribution of imaging?]

Thyroid imaging has an essentially diagnostic value, but is also plays a role in definition of indications and operative techniques. Ultrasound is the most useful examination. Scintigraphy has become less useful, but remains indicated in hyperthyroidism and in certain retrosternal goitres inaccessible to ultrasound. The other examinations only have a limited value.

Indications and limits of ultrasound-guided cytology in the management of nonpalpable thyroid nodules

Although ultrasound (US)-guided fine needle aspiration biopsy (FNAB) is widely prescribed in nonpalpable thyroid nodules, the goal of this study was to define precisely the indications and limits of US-FNAB in a series of 450 nonpalpable nodules. Among 94 surgically controlled cases, 20 (8 infracentimetric and 12 centimetric or supracentimetric) carcinomas were diagnosed. The diagnosis of malignancy was successfully made by US-FNAB in 16 of 20 carcinomas, 3 were missed because of insufficient cytological material, and 1 was misdiagnosed. US-FNAB sensitivity and specificity were 94% and 63%, respectively. A logistic model indicated that nodule size (P < 0.6) was not associated with histological diagnosis, but that solid hypoechoic features were more likely to be malignant (P < 0.0003), with US sensitivity and specificity for malignancy of 80% and 70%, respectively. Logistic regression indicated that adequate cytological material significantly increased with nodule size (P < 0.0001). This result outlined the limits of US-FNAB in small nodules. Hence, indication of US-FNAB appears judicious in centimetric or supracentimetric nodules or in solid and hypoechoic ones. Such a management would allow the discovery of 15 of 20 carcinomas and would avoid 16% of unnecessary biopsies.

Differential transferrin receptor density in human colorectal cancer: A potential probe for diagnosis and therapy

Transferrin receptor density was investigated in human colorectal surgical specimens. Crude membranes were prepared from 23 cancer tumors (adenocarcinoma or malignant villous tumor) and 3 non-cancer tumors (polyadenoma or villous tumor) and 26 adjacent control mucosa. Contrary to non-cancer tumors, Scatchard analysis of 125I-transferrin binding data evidenced higher maximal transferrin binding capacity and lower dissociation constant in cancer tissues (Bmax cancer 1.828+/-0.320 nmol/g, Kd 24.1+/-4.7 nM), as compared to paired control colonic mucosa (Bmax contol 0.851+/-0.182 nmol/g, Kd 30.7+/-7.3 nM), paired t-tests: Bmax p<0.001, Kd p<0.05). As the cancer/control Bmax ratio was 2.6+/-0.4,transferrin carrier constructs should be proposed for cancer imaging or therapy.

[Management of 29 children with thyroid cancer following the Chernobyl accident]

As a consequence of the Chernobyl nuclear power plant accident, a considerable increase of thyroid cancer among contaminated children has been reported in Ukraine, Belarus and Russia. A group of 29 children aged from 5 months to 10 years (mean 4.7 years) at the time of the accident, with a papillary thyroid cancer, have been examined at the Pitié-Salpêtrière hospital in Paris. The cancer was discovered by systematic ultrasonography in only 25% of cases. No reliable dosimetric estimation was achieved. The initial surgical treatment was performed in Ukraine. Cervical lymph node and pulmonary metastases were present in 24 and 11 cases respectively. A complementary surgical treatment was necessary for 9 children and one to four radioiodine treatments were given to 24 children. With a mean delay of 7 years after the cancer discovery, an apparent cure or a remission was obtained for 20 children, 6 children have cervical lymph node metastases requiring a surgical treatment and 3 have evolving lung metastases. The management of the great number of foreseeable cases of thyroid cancer requires an improved systematic screening, a large number of rooms dedicated to high activity radioiodine treatments, funds for disposable material and training missions.

Artificial neural network as a tool to compensate for scatter and attenuation in radionuclide imaging

This study investigates the ability of artificial neural networks (ANN) to simultaneously correct for attenuation and Compton scattering in scintigraphic imaging.

METHODS

Three sets of experiments are conducted using images of radioactive sources with various shapes and distributions in a homogeneous medium. Numerical Monte Carlo simulations and physical phantom acquisitions of radioactive geometric sources provide the basic material for correction. Our method is based on the following assumptions: information needed to correct for scattering can be extracted from the energy spectrum at each pixel without any assumption concerning the source distribution, and two diametrically opposed energy spectrum acquisitions yield enough information on the source location in the diffusing medium for simultaneous correction for attenuation and scattering.

RESULTS

Qualitative and quantitative evaluations of scatter correction by ANN demonstrate its ability to perform scatter correction from the energy spectra observed in each pixel. By using the energy spectra of incident photons detected in two diametrically opposed images, multilayer neural networks are able to perform a proper restitution of projection images without any assumption on geometry or position of radioactive sources in simple geometric cases. ANN corrections compare favorably to those provided by five of the most popular methods. A satisfying correction of both scatter and attenuation is observed for a human pelvis scan obtained during routine clinical practice.

CONCLUSION

An ANN is an efficient tool for attenuation and Compton scattering in simple model cases. The results obtained for routine scintigrams in a much more complex situation are strong incentives for performing further studies.

[Repeated thyroid surgery. Indications and results]

OBJECTIVES

To analyze the histology results and to assess operative risk of iterative operations for thyroid surgery.

PATIENTS AND METHODS

A total of 249 re-operations were performed in 248 patients over a 6.5 year period. Two groups of patients were defined according to the indications for re-operation. Group 1: 80 patients; pathology examination of the surgical specimen discovered thyroid cancer. Group 2: 169 patients; recurrent nodular goitre after an initially benign disease.

RESULTS

In group 1, 14 cancers were bilateral (17.5%) and 7 patients had cervical node metastases (8.8%). In group 2, 19 cancers were discovered (11.1%), including 5 cases with cervical node invasion (26.3%) and 4 with visceral metastases (21.1%). Twenty complications occurred in 20 patients (8%): compressive cervical hematomas (n = 3, 1.2%), recurrent nerve palsy (n = 7, 2.8%), hypoparathyroidism (n = 9, 3.6%; including 3 definitive cases, 1.2%) and mediastinitis (n = 1). These complications were significantly more frequent in patients re-operated for hyperthyroidism or those who had a past history of more than one cervicotomy.

CONCLUSION

The frequency of bilateral cancer justifies completing thyroidectomy after partial thyroidectomy. The rate of definitive complications after re-operations is greater than first line cervicotomy but is low enough to allow iterative surgery using rigorous procedure in selected patients.

Biparietal diameter in twins at gestational weeks 18-32. Differences and similarities. Le Groupe Romulus

OBJECTIVE

To examine twin similarities on biparietal diameter (BPD) measurements by zygosity (monozygotic [MZ] and dizygotic [DZ]) and chorionicity (monochorionic [MC] and dichorionic [DC]) and their evolution during pregnancy.

METHOD

A sample of 54 pairs of twins (43 DZ sets, 11 MZ sets [7 MC and 4 DC]) was constructed using retrospective data. Despite the small sample size, our data were complete, and, for the first time we measured different fetal parameters on digital ultrasound images outside routine examination. The intraexaminer and interexaminer reliability of BPD measurement was significant (r = .95, P < .001).

RESULTS

In this study, developmental results indicate significant linear regression coefficient (R) through the whole period of gestation (r = .96, P < .001), though product moment correlations comparing the periods of gestation two by two are weaker. The distribution of BPD values was slightly wider at the 28th week and markedly wider at the 32nd week than that at the 18th and 23rd weeks. The intraclass correlations of DZ and MZ (MC and DC) twins were examined at the 18th, 23rd, 28th and 32nd weeks of amenorhea. The intraclass correlations of DZ twins were significant through the whole period of gestation (r = .45, P = .001; r = .27, P = .04; r = .36, P = .008; and r = .42, P = .002, respectively), whereas the intraclass correlations of MZ twins were significant only at the 18th, 23rd and 28th weeks (r = .73, P = .002; r = .69, P = .005; r = .49, P = .047, respectively). We found significant within-variance differences not only between DZ and DC-MZ but also between DC-MZ and MC-MZ in late gestation.

CONCLUSION

Our analysis of twin BPD development demonstrated that zygosity and chorionicity type are both important determinants of twin fetal development.

Non-invasive assessment of technetium-99m albumin transit time distribution in the pulmonary circulation by first-pass angiocardiography

This study describes a non-invasive method for assessment of the lung transit time distribution of a tracer, using first-pass technetium-99m albumin angiocardiography and a model-free method of deconvolution. Ten patients received a first injection of 1 MBq kg-1 in the external jugular vein to position a gamma camera in the left anterior oblique position and two additional injections (5 MBq kg-1) to record first-pass angiocardiographic data. Right and left ventricular time-activity curves were derived from regions of interest every 0.5 s over a 1-min period. The left ventricular curve was deconvoluted by the right ventricular curve to obtain the lung transport function. The deconvolution procedure was based on a modified version of the Kalman filtering technique. The procedure was repeated at an interval of 30 min in eight patients. Two patients were re-examined up to 2 years later. Skewness, kurtosis and relative dispersion of the distributions did not change over time. We also found that the distribution, once normalized by its first moment, was independent of isolated changes in heart rate or cardiac output. Comparison of curve shapes at an interval of 30 min by point by point analysis demonstrated the reproducibility of the technique. We conclude that computation of the pulmonary transit time distribution of 99mTc-albumin from a standard angiocardiography procedure by model-free deconvolution is reliable and reproducible over time. We suggest that it may be a valuable tool for the non-invasive follow-up of the pulmonary circulation.

[Struma ovarii or malignant ovarian goiter. A case]

BACKGROUND

We report a case of follicular struma ovarii observed in an ovary teratoma without metastatic dissemination.

CASE REPORT

A right ovarian tumor was discovered at ultrasound examination in a 31-year-old woman complaining of low abdominal pain. The patient underwent laparoscopic exploration and a 4-cm cystic mass of the right ovary was removed. Microscopic examination showed a malignant struma ovarii of the follicular type with vascular space invasion; other teratomous elements were identified. Immunohistochemical staining for thyroglobulin confirmed the nature of the tumor. The patient was treated by complete right ovariectomy followed by total thyroidectomy and administration of radioactive iodine (99 mCi I-131). Repeat I-131 body scan performed at 6 months was normal.

DISCUSSION

Struma ovarii is a rare type of ovarian teratoma, consisting mainly of thyroid tissue. The incidence of malignant struma ovarii is below 1% and fewer than two dozen cases with distant metastases have been reported. The major problem associated with struma ovarii has been the establishment of criteria for malignancy.

Advantages of SPECT in technetium-99m-sestamibi parathyroid scintigraphy

We demonstrate several advantages of SPECT in parathyroid scintigraphy.

METHODS

Forty-four parathyroid 99mTc-MIBI scintigrams were obtained before surgery in 43 patients suffering from hyperparathyroidism. For each patient, we obtained dynamic views and planar and SPECT images of the neck and thorax. For 15 patients, we also acquired a delayed static view of the neck 2 hr after tracer injection. Abnormal thyroid-area glands were detected with factor analysis of dynamic structure (FADS) of the initial dynamic acquisition. In the 15 patients with delayed views of the neck, we compared FADS and the double-phase study results to detect glands in the thyroid uptake area. Glands outside the thyroid area were demonstrated on planar views. The location of enlarged glands was more precisely defined on the tomographic slices. The anatomic and histologic findings and the evolution of hypercalcemia after surgery were taken as reference.

RESULTS

Sixty-four abnormal glands were found during surgery, including 39 observed in patients who underwent reoperation for persistent or recurrent hyperparathyroidism. Twenty-two of these glands were in an abnormal location, including 10 in the mediastinum. SPECT allowed the detection of three glands not demonstrated on planar views or FADS. Fifty-eight glands were correctly localized scintigraphically, including 34 in patients who underwent reoperation. Therefore, SPECT raised the sensitivity from 86% to 90.5% and from 79.5% to 87% in the reoperated patients. Tracer uptake in the low mediastinal area was better analyzed on tomographic slices than on planar views. Only seven false-positive results were depicted by planar views or FADS; none were depicted on SPECT.

CONCLUSION

A combination of FADS and SPECT permits detection of small glands, even in a posterior location, inside or outside the thyroid area. This scintigraphic method enables the surgeon to define more precisely details about the location of the enlarged gland and contributes to improved parathyroid surgery.

The effects of triiodothyronine on hemodynamic status and cardiac function in potential heart donors

Brain death is associated with altered cardiac function and low concentrations of circulating triiodothryronine (T3). However, the effects of T3 administration on hemodynamic status and cardiac function in potential heart donors remain controversial. Thirty-seven brain-dead patients were randomly and blindly allocated to receive an intravenous bolus of either 0.2 microgram/kg T3 (n = 19) or saline placebo (n = 18). Measurements included conventional hemodynamic and echocardiographic variables of cardiac volume conditions and systolic function of the left ventricle (fractional area change [FAC], velocity of myocardial fiber shortening) using a transesophageal probe, arterial and mixed venous blood gas parameters, and serum thyroid hormone concentrations. The mean concentration of T3 was 1.86 +/- 1.55 pmol/L, and only six patients (16%) had normal values of T3 in control conditions. There was no significant correlation between T3 concentration and FAC (R = 0.17, not significant). All patients receiving T3 had normalized serum T3 concentration (7.55 +/- 2.56 pmol/L) in contrast to patients receiving saline (1.48 +/- 1.26 pmol/L). No significant differences in hemodynamic and echocardiographic parameters were observed between the placebo and T3 groups. Indeed, FAC remained unchanged after T3 (44% +/- 17% vs 46% +/- 22%) or placebo (47% +/- 18% vs 50% +/- 14%) administration. In 20 patients with impaired left ventricular function (FAC < 50%), FAC remained unchanged after T3 (n = 10; 34% +/- 12% vs 30% +/- 10%) or placebo (n = 10; 38% +/- 12% vs 35% +/- 13%) administration. In 17 patients in whom organ harvesting was delayed, transesophageal echocardiography was performed 6 h later and no significant changes in FAC were noted in the T3 group (n = 8; 49% +/- 17% vs 44% +/- 17%) and the placebo group (n = 9; 51% +/- 18% vs 47% +/- 18%). In conclusion, T3 administration did not improve hemodynamic status and myocardial function in brain-dead patients, suggesting that the euthyroid sick syndrome is not the main determinant of myocardial dysfunction in these patients.

Factor analysis in successive hepatobiliary imaging of native and transplant livers

A young male suffering from fulminant hepatic failure of unknown origin had an auxiliary partial orthotopic liver transplantation performed. The aim of the present study was to test the performance of factor analysis of medical image sequences (FAMIS) in the post-transplantation monitoring of the graft and native liver functions.

METHODS

Four successive hepatobiliary studies within 63 days following transplantation using 99mTc-mebrofenin were performed (on days 13,20,34,63). The 60 one-minute dynamic series were subjected to two successive FAMIS procedures.

RESULTS

For all studies, except the first, FAMIS was able to extract three factor couples (factor images and factors or curves) those of the native liver, the graft liver and the biliary region. The factors time evolution in uptake and excretion components showed the correlations between clinical status and scintigraphic results and helped interpretation of biochemical tests.

CONCLUSION

The possible utility of systematic liver transplant monitoring by radionuclide hepatobiliary imaging in identification of complications requiring medical or surgical intervention in graft livers was demonstrated. Furthermore, our study showed the functional recovery potential of the native liver in patients suffering from fulminant hepatitis.

[Echography of thyroid nodules. The echography specialist facing the clinician's requirements]

The risk of malignancy in cases of unique non-functional thyroid nodules ranges from 5 to 20% and since definitive diagnosis can only be provided by the pathology examination, surgical removal could be planned in all cases. The clinician however also has the objective of proposing surgery to as few patients with benign nodules as possible and thus calls upon the echographist to help distinguish between malignant and benign nodules. Thus orders for echography carry an intrinsic request for diagnostic arguments, a precise analysis of the characteristics of the nodule and a description of possible multinodular dystrophy as well as an estimation of the probability of malignancy. The echographist's report must include a precise description of each thyroid lobe, the localization of the nodule, its size, contour, echostructure, echogenicity and calcifications. The cervical lymph node chains must also be explored. An analysis of the surrounding parenchyma can frequently confirm multinodular dystrophy. The size of the nodule is the determining factor in predicting malignancy. While for very small nodules, less than 1 cm in diameter, the malignant nature cannot be reasonably predicted, and inversely for very large nodules, invading an entire lobe, it is usually evident, for intermediate sized nodules, echography is a strategic diagnostic tool. No sign is pathognomonic but an association of arguments can favour malignancy: an unique isolated nodule, irregular contours, lymph node enlargement greater than 1 cm. Hypoechogenicity is another important characteristic with a positive predictive value of 50% to 63%. Overall, the sensitivity of echography is good at 75% with specificity of 61 to 83%.(ABSTRACT TRUNCATED AT 250 WORDS)

Identifying abnormal parathyroid glands in the thyroid uptake area using technetium-99m-sestamibi and factor analysis of dynamic structures

A rapid (25 min) single tracer scintigraphic method to localize parathyroid gland abnormalities was evaluated in 24 patients with hyperparathyroidism.

METHODS

Scintigraphy was performed with 99mTc-sestamibi prior to surgery. A 25-min dynamic series centered on the neck was acquired immediately after injection of 99mTc-MIBI. Two planar static views were obtained after 1 and 2 hr. To identify abnormal parathyroid tissue in the thyroid uptake area, a factor analysis of dynamic structure (FADS) was applied to the dynamic acquisition. The results were compared to the analysis of the two planar static views.

RESULTS

FADS demonstrated abnormal uptake of the tracer in the thyroid area for 26 of the 31 parathyroid glands found to be abnormal at surgery (5/6 adenomas, 21/25 hyperplastic glands). In three cases, FADS demonstrated parathyroid uptake despite the absence of parathyroid tissue at surgery. FADS revealed as specific and more sensitive than the visual analysis of the two static views, since only 13/30 glands were still visible after 1 hr, and 5/26 after 2 hr. Furthermore, a study with two static views was found to be less sensitive for the detection of hyperplastic glands.

CONCLUSION

FADS99mTc-MIBI is performed in less time than existing scintigraphic protocols. It is a promising method to detect abnormal parathyroid glands in the cervical area with a single tracer.

[Flow cytometry of thyroid tumors. Study of fresh tissue in 50 patients]

OBJECTIVES

A measurement of cell DNA content would be highly useful in determining the malignant nature of thyroid tumours in cases without distinctive features such as metastases, capsule invasion or emboli. Abnormal cell ploidy can be recognized with flow cytometry, but it is not known whether such results have diagnostic value. We therefore compared--in a double blind prospective study--the results of flow cytometry and pathologic diagnosis in fresh tumoural and non-tumoural thyroid cells.

METHODS

Fifty unselected cold thyroid nodules were obtained from 50 consecutive patients (40 women, 10 men; age 18-80 years; mean 46) who underwent surgery within a 6 month period. Surrounding non-tumoural tissue was also obtained in 46 of them. Cell ploidy and the percentage of cells in each cell phase was determined with flow cytometry for both tumoural and nontumoural tissues. Two pathologists, unaware of the flow cytometric results, independently established the histologic diagnosis according to the WHO classification.

RESULTS

The pathologic diagnosis was carcinoma in 7 cases (papillary carcinoma 6, vesicular carcinoma 1) and benign adenomas in 43 (29 macrovesicular, 11 microvesicular, 3 oncocytal). All the non-tumoural tissue samples were diploid. All 7 carcinomas were diploid and 10 of the 43 benign adenomas were aneuploid (4 near-diploid, 3 hyperploid, 1 near-tetraploid, 2 multiploid). The mean proliferation index was increased in 5 diploid tumours.

CONCLUSION

These findings confirm that cell ploidy measured by flow cytometry is of no diagnostic value in the thyroid gland. It was also revealed that aneuploidy in adenomas may be related to tissue rearrangements of undetermined prognostic significance.

Automated interpretation of disk diffusion antibiotic susceptibility tests with the radial profile analysis algorithm

An original algorithm referred to as the radial profile analysis algorithm was implemented on a Macintosh Quadra 700 computer to provide an automatic determination of the inhibition zone diameters of antibiotic susceptibility tests performed with the disk diffusion method. After digitization of the petri plate image, each antibiotic disk is recognized and labeled. Pixels of the local zone around each disk are then used for generating a profile pattern that is subjected to decision rules. The resulting estimate of the inhibition zone diameter is then automatically compared with conventional breakpoints for classifying the tested strain in one of the clinical categories of antibiotic susceptibility. The program is also able to request a human reading for some rare plates difficult to interpret. The algorithm accuracy was tested by comparing the results with a combination of independent human measurements performed on the tested plates. The test sample was composed of 98 strains, and 2,552 tests of 40 distinct antibiotics were subjected to the analysis. The difference between the automatic and human diameter estimates was less than 4 mm in 90% of the tests. The agreement between the automatic and human clinical categorizations amounted to 95.5%, and severe (major and very major) disagreements were found in 5.6% of the tests performed with staphylococci but only 0.3% of the tests with gram-negative rods. We conclude that the radial profile analysis algorithm is a solid backbone for an automatic system dedicated to the clinical interpretation of disk diffusion antibiotic susceptibility tests.

Computer-assisted individual estimation of radioiodine thyroid uptake in Grave's disease

A computer-assisted Bayesian individual estimation of radioiodine thyroid uptake kinetics for patients suffering from Grave's disease is proposed. The program provides a fast computation of the activity to be administered to a given patient to achieve a target thyroid absorbed dose. This determination relies upon the patient biological covariates and upon a small number of measurements performed during a preliminar kinetic study of radioiodine thyroid uptake. Our results indicate that a two-sample Bayesian approach is reliable when external thyroid counts are performed at 2 h and 168 h after a test dose and has advantages over conventional kinetic experiments in terms of patient acceptability. This method is implemented on widespread computers and interfaced with a patient database. An interactive user interface with in-line data checking is provided. The program could be also a tool to better study the relationship between the absorbed dose and the clinical effect.

New method of three-dimensional analysis of bipedal locomotion for the study of displacements of the body and body-parts centers of mass in man and non-human primates: evolutionary framework

The current biomechanical interpretation of the chimpanzee's bipedal walking argues that larger lateral and vertical displacements of the body center of mass occur in the chimpanzee's "side-to-side" gait than in the human striding gait. The evolutionary hypothesis underlying this study is the following: during the evolution of human bipedalism one of the necessary changes could have been the progressive reduction of these displacements of the body center of mass. In order to quantitatively test this hypothesis, it is necessary to obtain simultaneously the trajectories of the centers of mass of the whole body and of the different body parts. To solve this problem, a new method of three-dimensional analysis of walking, associated with a volumetric modelling of the body, has been developed based on finite-element modeling. An orthogonal synchrophotographic device yielding four synchronous pictures of the walking subject allows a qualitative analysis of the photographic sequences together with the results of their quantitative analysis. This method was applied to an adult man, a 3-year-old girl and a 9-year-old male chimpanzee. Our results suggest that the trajectory of the body center of mass of the human is distinguished from that of the chimpanzee not by a lower movement amplitude but by the synchronization of the transverse and vertical displacements into two periodic curves in phase with one another. The non-human primate uses its repertoire of arboreal movements in its bipedal terrestrial gait, provisionally referred to as a "rope-walker" gait. We show that the interpretation of a "side-to-side" gait is not applicable to the chimpanzee. We argue that similarly this interpretation and the initial hypothesis presuppose a basic symmetric structure of the gait, in relation to the sagittal plane of progression, similar to the human one. This lateral symmetry of the right and left displacements of the center of gravity, in phase with the right and left single supports of walking, is probably a very derived feature of the human gait. We suggest that low lateral and vertical displacements of the body center of mass are not indicative of a progressive bipedal gait and we discuss the new evolutionary implications of our results.

Tissue distribution of 131I radiolabeled transferrin in the athymic nude mouse: localization of a human colon adenocarcinoma HT-29 xenograft

The tissue distribution of 131I-transferrin (131I-Tf) was studied in athymic nude mice having s.c. human colonic adenocarcinoma HT-29 xenografts. Four days after 131I-Tf injection, the 131I-specific activity measured in the HT-29 tumor, i.e. amount of radioactivity per gram of fresh tissue, represented 0.31 +/- 0.09% of the injected radioactivity and was 1.90 fold more than that measured in the murine colon (P less than 0.05). After correction for intravascular 131I-Tf as estimated by means of 99mTc-Sn in vivo labeling of red blood cells, the 131I specific activity observed in the HT-29 tumor was 7.21 fold more than that observed in the murine colon. This subtracting method enabled us to localize a HT-29 tumor xenograft by gamma scintigraphy of the entire animal and demonstrated that 131I-Tf could be a non-specific but potent marker for human colon cancer.

Complete iodide trapping defect in two cases with congenital hypothyroidism: adaptation of thyroid to huge iodide supplementation

Two cases of congenital defect in iodide trapping mechanism are related. The absence of thyroid and gastric concentration of 99mTcO4 led to the diagnosis. The study of saliva and gastric:serum concentration ratios confirmed the complete defect. The kinetics of radioiodine studied by external detection showed an early simultaneous decay in the thyroid, the stomach and the left ventricle. Thyroid accumulation of 131I, demonstrated by camera imaging, was estimated to be 0.1% at 48 h. It probably originated from simple diffusion. Iodide supplementation was progressively increased to 4.5 g and 10 g day-1 respectively. It resulted in a normalization of all parameters. Huge doses of iodide did not result in any evidence of hyperthyroidism as TSH rose normally after TRH. Intermittent iodide supplementation in one case could not maintain euthyroidism longer than a few weeks. Daily treatment, therefore, seems necessary.

Quantitative characterization of blood rheological behavior in transient flow with a model including a structure parameter

Transient rheological behavior of blood which involves non newtonian viscosity, elasticity and thixotropy can be modelized with a Maxwell rheological state equation which depends on a structure parameter having dimension of a shear rate. Identification of the model parameters leads to use an exponential apparent shear rate step and to use recursive filters for taking into account the impulse response of the viscometer servo-control device. Typical results for a normal blood sample are given.

Would I-123 di-iodotyrosine provide a harmless deiodination test? Concise communication

Defective iodotyrosine deiodinase activity may benefit from a specific treatment, thus requiring an unequivocal diagnosis. In reported cases this diagnosis has been obtained from an in vivo deiodination test making use of di-iodotyrosine (DIT) labeled either with I-131 or I-125. Dosimetric calculation indicates that such tests may result in unacceptable irradiation of the thyroid of a child wrongly suspected of having defective iodotyrosine deiodinase activity; therefore other methods are needed. The use of I-123 DIT is shown to be feasible, but even a 1:30 reduction in the thyroid dose still remains too high. Suppression of thyroid I- uptake by ClO4-, together with I-125 DIT, eliminates almost all thyroid irradiation and provides a sensitive, harmless, and rapid test.

Optimization of ultrathin-film nonresonant Raman spectra provided by combining a light-trapping device, a high N.A. objective, and a spectrometer

The association of a four-media stratified illumination device and a high N.A. objective allowed us to obtain nonresonant Raman spectra of ultrathin films. The signal-to-noise ratio provided by this combination was computed. From this ratio we derived the optimization of the illumination conditions and optical coupling of the objective with the sample and with the spectrometer.