Free-running cardiac and respiratory motion-resolved 5D whole-heart coronary cardiovascular magnetic resonance angiography in pediatric cardiac patients using ferumoxytol

BACKGROUND

Coronary cardiovascular magnetic resonance angiography (CCMRA) of congenital heart disease (CHD) in pediatric patients requires accurate planning, adequate sequence parameter adjustments, lengthy scanning sessions, and significant involvement from highly trained personnel. Anesthesia and intubation are commonplace to minimize movements and control respiration in younger subjects. To address the above concerns and provide a single-click imaging solution, we applied our free-running framework for fully self-gated (SG) free-breathing 5D whole-heart CCMRA to CHD patients after ferumoxytol injection. We tested the hypothesis that spatial and motion resolution suffice to visualize coronary artery ostia in a cohort of CHD subjects, both for intubated and free-breathing acquisitions.

METHODS

In 18 pediatric CHD patients, non-electrocardiogram (ECG) triggered 5D free-running gradient echo CCMRA with whole-heart 1 mm3 isotropic spatial resolution was performed in seven minutes on a 1.5T CMR scanner. Eleven patients were anesthetized and intubated, while seven were breathing freely without anesthesia. All patients were slowly injected with ferumoxytol (4 mg/kg) over 15 minutes. Cardiac and respiratory motion-resolved 5D images were reconstructed with a fully SG approach. To evaluate the performance of motion resolution, visibility of coronary artery origins was assessed. Intubated and free-breathing patient sub-groups were compared for image quality using coronary artery length and conspicuity as well as lung-liver interface sharpness.

RESULTS

Data collection using the free-running framework was successful in all patients in less than 8 min; scan planning was very simple without the need for parameter adjustments, while no ECG lead placement and triggering was required. From the resulting SG 5D motion-resolved reconstructed images, coronary artery origins could be retrospectively extracted in 90% of the cases. These general findings applied to both intubated and free-breathing pediatric patients (no difference in terms of lung-liver interface sharpness), while image quality and coronary conspicuity between both cohorts was very similar.

CONCLUSIONS

A simple-to-use push-button framework for 5D whole-heart CCMRA was successfully employed in pediatric CHD patients with ferumoxytol injection. This approach, working without any external gating and for a wide range of heart rates and body sizes provided excellent definition of cardiac anatomy for both intubated and free-breathing patients.

Motion compensated whole-heart coronary cardiovascular magnetic resonance angiography using focused navigation (fNAV)

BACKGROUND

Radial self-navigated (RSN) whole-heart coronary cardiovascular magnetic resonance angiography (CCMRA) is a free-breathing technique that estimates and corrects for respiratory motion. However, RSN has been limited to a 1D rigid correction which is often insufficient for patients with complex respiratory patterns. The goal of this work is therefore to improve the robustness and quality of 3D radial CCMRA by incorporating both 3D motion information and nonrigid intra-acquisition correction of the data into a framework called focused navigation (fNAV).

METHODS

We applied fNAV to 500 data sets from a numerical simulation, 22 healthy subjects, and 549 cardiac patients. In each of these cohorts we compared fNAV to RSN and respiratory resolved extradimensional golden-angle radial sparse parallel (XD-GRASP) reconstructions of the same data. Reconstruction times for each method were recorded. Motion estimate accuracy was measured as the correlation between fNAV and ground truth for simulations, and fNAV and image registration for in vivo data. Percent vessel sharpness was measured in all simulated data sets and healthy subjects, and a subset of patients. Finally, subjective image quality analysis was performed by a blinded expert reviewer who chose the best image for each in vivo data set and scored on a Likert scale 0-4 in a subset of patients by two reviewers in consensus.

RESULTS

The reconstruction time for fNAV images was significantly higher than RSN (6.1 ± 2.1 min vs 1.4 ± 0.3, min, p < 0.025) but significantly lower than XD-GRASP (25.6 ± 7.1, min, p < 0.025). Overall, there is high correlation between the fNAV and reference displacement estimates across all data sets (0.73 ± 0.29). For simulated data, healthy subjects, and patients, fNAV lead to significantly sharper coronary arteries than all other reconstruction methods (p < 0.01). Finally, in a blinded evaluation by an expert reviewer fNAV was chosen as the best image in 444 out of 571 data sets (78%; p < 0.001) and consensus grades of fNAV images (2.6 ± 0.6) were significantly higher (p < 0.05) than uncorrected (1.7 ± 0.7), RSN (1.9 ± 0.6), and XD-GRASP (1.8 ± 0.8).

CONCLUSION

fNAV is a promising technique for improving the quality of RSN free-breathing 3D whole-heart CCMRA. This novel approach to respiratory self-navigation can derive 3D nonrigid motion estimations from an acquired 1D signal yielding statistically significant improvement in image sharpness relative to 1D translational correction as well as XD-GRASP reconstructions. Further study of the diagnostic impact of this technique is therefore warranted to evaluate its full clinical utility.

Similarity-driven multi-dimensional binning algorithm (SIMBA) for free-running motion-suppressed whole-heart MRA

PURPOSE

Whole-heart MRA techniques typically target predetermined motion states, address cardiac and respiratory dynamics independently, and require either complex planning or computationally demanding reconstructions. In contrast, we developed a fast data-driven reconstruction algorithm with minimal physiological assumptions and compatibility with ungated free-running sequences.

THEORY AND METHODS

We propose a similarity-driven multi-dimensional binning algorithm (SIMBA) that clusters continuously acquired k-space data to find a motion-consistent subset for whole-heart MRA reconstruction. Free-running 3D radial data sets from 12 non-contrast-enhanced scans of healthy volunteers and six ferumoxytol-enhanced scans of pediatric cardiac patients were reconstructed with non-motion-suppressed regridding of all the acquired data ("All Data"), with SIMBA, and with a previously published free-running framework (FRF) that uses cardiac and respiratory self-gating and compressed sensing. Images were compared for blood-myocardium sharpness and contrast ratio, visibility of coronary artery ostia, and right coronary artery sharpness.

RESULTS

Both the 20-second SIMBA reconstruction and FRF provided significantly higher blood-myocardium sharpness than All Data in both patients and volunteers (P < .05). The SIMBA reconstruction provided significantly sharper blood-myocardium interfaces than FRF in volunteers (P < .001) and higher blood-myocardium contrast ratio than All Data and FRF, both in volunteers and patients (P < .05). Significantly more ostia could be visualized with both SIMBA (31 of 36) and FRF (34 of 36) than with All Data (4 of 36) (P < .001). Inferior right coronary artery sharpness using SIMBA versus FRF was observed (volunteers: SIMBA 36.1 ± 8.1%, FRF 40.4 ± 8.9%; patients: SIMBA 35.9 ± 7.7%, FRF 40.3 ± 6.1%, P = not significant).

CONCLUSION

The SIMBA technique enabled a fast, data-driven reconstruction of free-running whole-heart MRA with image quality superior to All Data and similar to the more time-consuming FRF reconstruction.

Measurement accuracy of prototype non-contrast, compressed sensing-based, respiratory motion-resolved whole heart cardiovascular magnetic resonance angiography for the assessment of thoracic aortic dilatation: comparison with computed tomography angiography

BACKGROUND

Patients with thoracic aortic dilatation who undergo annual computed tomography angiography (CTA) are subject to repeated radiation and contrast exposure. The purpose of this study was to evaluate the feasibility of a non-contrast, respiratory motion-resolved whole-heart cardiovascular magnetic resonance angiography (CMRA) technique against reference standard CTA, for the quantitative assessment of cardiovascular anatomy and monitoring of disease progression in patients with thoracic aortic dilatation.  METHODS: Twenty-four patients (68.6 ± 9.8 years) with thoracic aortic dilatation prospectively underwent clinical CTA and research 1.5T CMRA between July 2017 and November 2018. Scans were repeated in 15 patients 1 year later. A prototype free-breathing 3D radial balanced steady-state free-precession whole-heart CMRA sequence was used in combination with compressed sensing-based reconstruction. Area, circumference, and diameter measurements were obtained at seven aortic levels by two experienced and two inexperienced readers. In addition, area and diameter measurements of the cardiac chambers, pulmonary arteries and pulmonary veins were also obtained. Agreement between the two modalities was assessed with intraclass correlation coefficient (ICC) analysis, Bland-Altman plots and scatter plots.

RESULTS

Area, circumference and diameter measurements on a per-level analysis showed good or excellent agreement between CTA and CMRA (ICCs > 0.84). Means of differences on Bland-Altman plots were: area 0.0 cm2 [- 1.7; 1.6]; circumference 1.0 mm [- 10.0; 12.0], and diameter 0.6 mm [- 2.6; 3.6]. Area and diameter measurements of the left cardiac chambers showed good agreement (ICCs > 0.80), while moderate to good agreement was observed for the right chambers (all ICCs > 0.56). Similar good to excellent inter-modality agreement was shown for the pulmonary arteries and veins (ICC range 0.79-0.93), with the exception of the left lower pulmonary vein (ICC < 0.51). Inter-reader assessment demonstrated mostly good or excellent agreement for both CTA and CMRA measurements on a per-level analysis (ICCs > 0.64). Difference in maximum aortic diameter measurements at baseline vs follow up showed excellent agreement between CMRA and CTA (ICC = 0.91).

CONCLUSIONS

The radial whole-heart CMRA technique combined with respiratory motion-resolved reconstruction provides comparable anatomical measurements of the thoracic aorta and cardiac structures as the reference standard CTA. It could potentially be used to diagnose and monitor patients with thoracic aortic dilatation without exposing them to radiation or contrast media.

Deep Learning to Automate Reference-Free Image Quality Assessment of Whole-Heart MR Images

Purpose

To develop and characterize an algorithm that mimics human expert visual assessment to quantitatively determine the quality of three-dimensional (3D) whole-heart MR images.

Materials and Methods

In this study, 3D whole-heart cardiac MRI scans from 424 participants (average age, 57 years ± 18 [standard deviation]; 66.5% men) were used to generate an image quality assessment algorithm. A deep convolutional neural network for image quality assessment (IQ-DCNN) was designed, trained, optimized, and cross-validated on a clinical database of 324 (training set) scans. On a separate test set (100 scans), two hypotheses were tested: (a) that the algorithm can assess image quality in concordance with human expert assessment as assessed by human-machine correlation and intra- and interobserver agreement and (b) that the IQ-DCNN algorithm may be used to monitor a compressed sensing reconstruction process where image quality progressively improves. Weighted κ values, agreement and disagreement counts, and Krippendorff α reliability coefficients were reported.

Results

Regression performance of the IQ-DCNN was within the range of human intra- and interobserver agreement and in very good agreement with the human expert (R ² = 0.78, κ = 0.67). The image quality assessment during compressed sensing reconstruction correlated with the cost function at each iteration and was successfully applied to rank the results in very good agreement with the human expert.

Conclusion

The proposed IQ-DCNN was trained to mimic expert visual image quality assessment of 3D whole-heart MR images. The results from the IQ-DCNN were in good agreement with human expert reading, and the network was capable of automatically comparing different reconstructed volumes.Supplemental material is available for this article.© RSNA, 2020.

A quantitative comparison between a navigated Cartesian and a self-navigated radial protocol from clinical studies for free-breathing 3D whole-heart bSSFP coronary MRA

PURPOSE

Navigator-gated 3D bSSFP whole-heart coronary MRA has been evaluated in several large studies including a multi-center trial. Patient studies have also been performed with more recent self-navigated techniques. In this study, these two approaches are compared side-by-side using a Cartesian navigator-gated and corrected (CNG) and a 3D radial self-navigated (RSN) protocol from published patient studies.

METHODS

Sixteen healthy subjects were examined with both sequences on a 1.5T scanner. Assessment of the visibility of coronary ostia and quantitative comparisons of acquisition times, blood pool homogeneity, and visible length and sharpness of the right coronary artery (RCA) and the combined left main (LM)+left anterior descending (LAD) coronary arteries were performed. Paired sample t-tests with P < .05 considered statistically significant were used for all comparisons.

RESULTS

The acquisition time was 5:40 ± 0:28 min (mean ± SD) for RSN, being significantly shorter than the 16:59 ± 5:05 min of CNG (P < .001). RSN images showed higher blood pool homogeneity (P < .001). All coronary ostia were visible with both techniques. CNG provided significantly higher vessel sharpness in the RCA (CNG: 50.0 ± 8.6%, RSN: 34.2 ± 6.9%, P < .001) and the LM+LAD (CNG: 48.7 ± 6.7%, RSN: 32.3 ± 7.1%, P < .001). The visible vessel length was significantly longer in the LM+LAD using CNG (CNG: 9.8 ± 2.7 cm, RSN: 8.5 ± 2.6 cm, P < .05) but not in the RCA (CNG: 9.7 ± 2.3 cm, RSN: 9.3 ± 2.9 cm, P = .29).

CONCLUSION

CNG provided superior vessel sharpness and might hence be the better option for examining coronary lumina. However, its blood pool inhomogeneity and prolonged and unpredictable acquisition times compared to RSN may make clinical adoption more challenging.

Natively fat-suppressed 5D whole-heart MRI with a radial free-running fast-interrupted steady-state (FISS) sequence at 1.5T and 3T

PURPOSE

To implement, optimize, and test fast interrupted steady-state (FISS) for natively fat-suppressed free-running 5D whole-heart MRI at 1.5 tesla (T) and 3T.

METHODS

FISS was implemented for fully self-gated free-running cardiac- and respiratory-motion-resolved radial imaging of the heart at 1.5T and 3T. Numerical simulations and phantom scans were performed to compare fat suppression characteristics and to determine parameter ranges (number of readouts [NR] per FISS module and TR) for effective fat suppression. Subsequently, free-running FISS data were collected in 10 healthy volunteers and images were reconstructed with compressed sensing. All acquisitions were compared with a continuous balanced steady-state free precession version of the same sequence, and both fat suppression and scan times were analyzed.

RESULTS

Simulations demonstrate a variable width and location of suppression bands in FISS that were dependent on TR and NR. For a fat suppression bandwidth of 100 Hz and NR ≤ 8, simulations demonstrated that a TR between 2.2 ms and 3.0 ms is required at 1.5T, whereas a range of 3.0 ms to 3.5 ms applies at 3T. Fat signal increases with NR. These findings were corroborated in phantom experiments. In volunteers, fat SNR was significantly decreased using FISS compared with balanced steady-state free precession (P < 0.05) at both field strengths. After protocol optimization, high-resolution (1.1 mm³ ) 5D whole-heart free-running FISS can be performed with effective fat suppression in under 8 min at 1.5T and 3T at a modest scan time increase compared to balanced steady-state free precession.

CONCLUSION

An optimal FISS parameter range was determined enabling natively fat-suppressed 5D whole-heart free-running MRI with a single continuous scan at 1.5T and 3T, demonstrating potential for cardiac imaging and noncontrast angiography.

Correcting versus resolving respiratory motion in free-breathing whole-heart MRA: a comparison in patients with thoracic aortic disease

Background

Whole-heart magnetic resonance angiography (MRA) requires sophisticated methods accounting for respiratory motion. Our purpose was to evaluate the image quality of compressed sensing-based respiratory motion-resolved three-dimensional (3D) whole-heart MRA compared with self-navigated motion-corrected whole-heart MRA in patients with known thoracic aorta dilation.

Methods

Twenty-five patients were prospectively enrolled in this ethically approved study. Whole-heart 1.5-T MRA was acquired using a prototype 3D radial steady-state free-precession free-breathing sequence. The same data were reconstructed with a one-dimensional motion-correction algorithm (1D-MCA) and an extradimensional golden-angle radial sparse parallel reconstruction (XD-GRASP). Subjective image quality was scored and objective image quality was quantified (signal intensity ratio, SIR; vessel sharpness). Wilcoxon, McNemar, and paired t tests were used.

Results

Subjective image quality was significantly higher using XD-GRASP compared to 1D-MCA (median 4.5, interquartile range 4.5–5.0 versus 4.0 [2.25–4.75]; p < 0.001), as well as signal homogeneity (3.0 [3.0–3.0] versus 2.0 [2.0–3.0]; p = 0.003), and image sharpness (3.0 [2.0–3.0] vs 2.0 [1.25–3.0]; p < 0.001). SIR with the 1D-MCA and XD-GRASP was 6.1 ± 3.9 versus 7.4 ± 2.5, respectively (p < 0.001); while signal homogeneity was 274.2 ± 265.0 versus 199.8 ± 67.2 (p = 0.129). XD-GRASP provided a higher vessel sharpness (45.3 ± 10.7 versus 40.6 ± 101, p = 0.025).

Conclusions

XD-GRASP-based motion-resolved reconstruction of free-breathing 3D whole-heart MRA datasets provides improved image contrast, sharpness, and signal homogeneity and seems to be a promising technique that overcomes some of the limitations of motion correction or respiratory navigator gating.

[Computer tomography in Greenland--a basis for establishment of the service]

The purpose of this study is to evaluate the consequences of referral of patients for medical reasons from Greenland to Denmark for computed tomography (CT) scans. Twenty-eight of 35 evaluable patients could have been treated following the information from the CT scans without the use of the resources of a university hospital (for instance rehabilitation of patients with cerebral infarction). The establishment of a CT scanning service in Greenland may reduce costs without a deterioration in medical care. Accordingly, the alternative seems attractive.

Numerical assessment of asymmetry at scintigraphy of normal joint pairs with (99)Tcm polyphosphate

Numerical analysis of (99)Tcm polyphosphate distribution in 1 348 selected, non-pathologic joint pairs revealed a significantly higher right-sided accumulation in 37 per cent, a left-sided dominance in 21 per cent and no significant side difference in the remaining 42 per cent. The most common level of asymmetry was the shoulder joint.

Intraosseous phlebography, intraosseous pressure measurements and 99mTC-polyphosphate scintigraphy in patients with various painful conditions in the hip and knee

Twenty-five patients with pain in the knee or hip were examined by means of bilateral intraosseous phlebography, intraosseous pressure measurements and 99mTechnetium polyphosphate scintigraphy. All patients with typical rest pain--either due to osteoarthritis or to the intraosseous engorgement-pain syndrome--showed venous stasis and increased pressure in the bone marrow near the painful joint and abnormally high uptake of the radiotracer. In patients with other types of pain this correlation was absent. The results indicate that 99mTechnetium polyphosphate scintigraphy can be used as a screening method in the diagnosis of the intraosseous engorgement-pain syndrome in patients with a typical history. However, increased isotope uptake in a joint region may be due to a variety of other causes. The identical findings with all three methods of investigation in patients with the intraosseous engorgement-pain syndrome and osteoarthritis suggest a common pathomechanism.

Scintigraphic skeletal changes in non-dialyzed patients with advanced renal failure

Technetium-99m-polyphosphate (Tc-PP) bone scintigraphy was performed in 51 patients with advanced renal failure in order to evaluate the applicability of this method in detection of metabolic bone changes in these patients. The creatinine clearance varied from 2 to 40 ml/min and none of the patients had previously been on dialysis treatment. The scintigrams were graded according to the focal and the generalized abnormal uptake of the tracer in the skeleton. 34 patients showed generalized scintigraphic changes and among these the changes in 18 patients were classified as severe. An inverse correlation was found between the kidney function and the generalized scintigraphic classification. Focal bone changes were found in 11 patients. In order to evaluate the influence of the lack of kidney function on the scintigraphic results, 3 patients with acute oliguric renal failure were examined. All had normal scintigrams. It is concluded that Tc-PP bone scintigraphy is a sensitive method in revealing renal osteodystrophy in non-dialyzed patients with advanced renal failure in agreement with previous reports on patients on chronic hemodialysis and after kidney transplantation.

Numerical assessment of bone scintigraphy in primary bone tumors and tumor-like conditions

Fifty-four tumors or tumor-like conditions in bone were studied by numerically assessed 99m-technetium polyphosphate scintigraphy. The uptake was expressed as a ratio of the uptake in the tumor region to the uptake in a corresponding region in the contralateral part of the body. In the malignant tumors there was marked variation in the uptake within each individual tumor group, a variation that rendered a differential diagnosis impossible. In general, the uptake was fairly high in malignant tumors and lower in benign ones. A ratio below 1.5 suggested the likelihood that the lesion was benign. The ratios also varied considerably with the site of the tumor and the patients' ages. Relatively low ratios were found for tumors of the trunk and for juxta-articular tumors in children, whereas higher and more varied ratios were observed in tumors of the peripheral skeleton in adults. It is concluded that numerically assessed scintigraphy is not a useful supplement to other methods used for diagnosing bone tumors.

Osteosarcoma of the metatarsal bones. Review of the literature and report of a case

A case of osteosarcoma affecting the third metatarsal bone is submitted. Below-knee amputation was performed, but the patient developed pulmonary metastases and died 1 year after the operation. The six cases of osteosarcoma in the metarsal bones published so far are reviewed. The prognosis for cases with this localization does not appear to differ from that for osteosarcoma in general.

Hemipelvectomy. Postoperative rehabilitation assessed on the basis of 41 cases

Rehabilitation was evaluated on the basis of 41 consecutive hemipelvectomies for malignant tumours. Owing to early metastasization and death, 11 patients were not supplied with prostheses, while prosthetic fitting was attempted in the remaining 30. Of this number 27 completed prosthetic training, with the result that 15 used their prosthesis, while 12 discarded it after some time, six because of poor general health owing to recurrence of the tumours and six because they felt that the prosthesis was too heavy and difficult to wear. Twenty-three returned to work. After elimination of the most severely tumour-affected patients, there were 19 one-year survivors without recurrence. Thirteen of them were using their prosthesis every day, and thirteen had gone back to work. Serious mental sequelae were found in five patients, including four with long-lasting exogenous depressions and one with anxiety neurosis.

Spontaneous regression of a malignant primary bone tumour

A histologically confirmed malignant, primary bone tumour in the pelvis, presumably an osteosarcoma, underwent spontaneous regression. The large tumour was inoperable and gave rise to severe pain as well as difficulty in walking. After 2 years of progression, with increasing desition improved spontaneously, and at present the patient is alive, almost symptom-free, after 6 years follow-up.

Autoradiography and histology in a case of idiopathic femoral head necrosis

The necrotic femoral head in a patient with a transplanted kidney was examined autoradiographically (with fluorine--18 and Technitium--99 m--Polyphosphate) and histologically (i.e. with long interval Tetracycline labellings). A well circumscribed area of necrotic bone was demonstrated in the weight bearing part of the caput giving evidence of a solitary infarction. The demarcation zone showed revascularization, and appositional bone formation accounted for the increased density. Foci of necrotic bone were observed further away from the necrotic area indicating an originally more extensive vascular insufficiency. In the subchondral bone a fissure had arisen probably due to rarefaction of bone during the process of revascularization. It is suggested that the vascular insufficiency was a result of a reduced resistance of the bone tissue altered by steroid therapy.

Comparison of 18F and 99mTc-polyphosphate in orthopedic bone scintigraphy

To compare 99mTc-polyphosphate and 18F for use in orthopedics, 79 patients were examined with both. Fifty cases were suitable for analysis. While the extraskeletal uptake of 18F was found to be negligible, 99mTc-polyphosphate may accumulate considerably in pathologic soft tissue, e.g., in soft-tissue tumors and in inflamed synovial tissue. This soft-tissue Tc accumulation may obscure the osseus uptake, notably in the examination of joint regions, commonly the regions of interest in orthopedics. After simultaneous administration of both agents, quantitative measurements were performed on specimens of bone and synovial tissue from diseased joints in human patients and in rabbits. The uptake of 99mTc-polyphosphate in synovial tissue was shown to be about seven times that of 18F, while their uptakes in bone were equal. In short, 99mTc-polyphosphate, a valuable tracer in general, is hardly the agent of choice in orthopedics.

Scintigraphic skeletal changes in uremic patients on regular hemodialysis

99Tcm-polyphosphate (Tc-PP) bone scintigraphy was performed in 30 consecutive uremic patients on regular hemodialysis and compared with a normal control group. 27 of the patients (90%) had pathological accumulation on the scintigrams, while roentgenographic abnormalities were present in only 10 patients (33%), indicating that scintigraphy is superior to X-ray in the early detection of skeletal changes in uremic patients. In the group with the most pronounced uptake on the scintigrams there was a preponderance of previously kidney-transplanted patients, while no correlation could be demonstrated between the severity of the scintigraphic findings and the duration of the hemodialysis period, the anephric state of the patients, the underlying kidney disease or the sex. It is suggested that intensive glucocorticoid treatment, even of short duration in the previously kidney-transplanted patients, may aggravate uremic osteodystrophy.

150 open fractures of the tibial shaft--the relation between necrosis of the skin and delayed union

In 150 open fractures of the tibial shaft a close relationship between the presence of skin necrosis and delayed union was found. The incidence of skin necrosis rose with the severity of trauma. It was high (22 per cent) among the fractures that were treated conservatively, but even higher (41 per cent) among those treated with primary osteosynthesis. Neither conventional conservative treatment nor osteosynthesis seems to be satisfactory as a primary treatment of the most severe cases. It is instead suggested that external fixation by the Hoffmann-Vidal technique should be combined with transposition of viable muscle tissue across denuded fractured bone areas according to the method of Ger.

Tumours of the thymic region. Symptomatology, diagnosis, treatment, and prognosis

Fifty-three patients operated on between 1952 and 1971 were originally diagnosed as having thymoma. Re-examination of the material shows that only half of these tumours were true thymomas. The rest were classified as malignant lymphomas, primary and secondary carcinomas, and a few haemangiomas. Half of the patients had symptoms at the time of diagnosis. However, in half of the asymptomatic cases the tumours had penetrated the capsule. Decisive in prognosis are the macroscopic findings around the capsule. Of 33 patients with infiltration of the capsule, 30 had died at the time of investigation. Twenty-five patients died within two years of operation, Twenty-five patients had thymomas, of which 14 were well defined. Twelve patients with thymomas suffered from myasthenia gravis. The treatment of choice of thymoma is total excision, if necessary enbloc, and if there is penetration of the capsule, radiotherapy should be given. None of the patients with a well-defined thymoma had died from their tumour while only two patients with infiltrating thymomas are still alive, Of eight patients with Hodgkin's disease located in the thymus, six had penetration of the capsule, and of these only one patient is still alive. Two patients with well-defined tumours are both alive. The treatment of localized Hodgkin's disease is excision and irradiation. The prognosis for patients with other malignant tumours was bad, the mean time of survival being less than six months.

Femoral head necrosis in renal transplanted patients. Evidence of a haemodynamic etiological factor

In a material of 197 consecutive renal allotransplanted patients, 15 patients developed femoral head necrosis on X-ray examination. Eleven of these patients developed the femoral head necrosis ipsilateral to the renal allograft. It is therefore suggested that the altered haemodynamics caused by the transplantation may be of pathogenic importance in the development of the femoral head necrosis.