Yutaka Naoi

Achilles Tendon After Percutaneous Surgical Repair: Serial MRI Observation of Uncomplicated Healing

OBJECTIVE The purpose of this study was to prospectively explore the MRI features of normal healing of the expected residual tendon gap in the Achilles tendon after percutaneous surgical repair. SUBJECTS AND METHODS MR images of the Achilles tendon were obtained approximately 4, 8, and 12 weeks after surgery. Assessment of MR images was focused on the presence of residual tendon gap and gap length, Achilles tendon contour, and contrast enhancement in the ruptured area. Cases of open surgical repair were used for comparison. We attempted to statistically compare the timing of tendon gap disappearance within the percutaneous surgical repair group and between the percutaneous and open surgical repair groups. RESULTS A total of 30 tendons repaired with percutaneous surgical technique and 10 repaired with open surgical technique were evaluated. At the first, second, and third MRI sessions of the percutaneous surgical repair group, a residual gap was found in 100%, 80%, and none of the tendons on T1-weighted images and in 87%, 63%, and none of the tendons on T2-weighted images. Achilles tendon contour was visualized in 30%, 90%, and 100% of the tendons on T1-weighted images and 90%, 100%, and 100% of the tendons on T2-weighted images. Intratendinous enhancement was present in 100%, 73%, and 7% of the tendons in the percutaneous surgical repair group. Ring-shaped peritendinous enhancement was recognized at the third session in all subjects. A significantly longer time was required for tendon gap disappearance after percutaneous than after open surgical repair. CONCLUSION The time course of the MR findings in the ruptured Achilles tendon after percutaneous surgical repair appears to reflect regular healing.

Pseudomesotheliomatous lung cancer mimicking mesothelioma on 18F-FDG PET/CT images: report of 2 cases

The authors report two cases of pseudomesotheliomatous lung cancer (PLC) detected by 18F-FDG PET/CT scan. 18F-FDG PET/CT clearly revealed the extent of the disease in both cases, a case of adenocarcinoma of the lung and a case of squamous cell carcinoma of the lung. Intense 18F-FDG uptake by the diffusely thickened pleurae and primary lesion was observed in both cases, and increased 18F-FDG uptake by a pelvic bone metastasis was observed in the case of squamous cell carcinoma. Although PLC is indistinguishable from malignant pleural mesothelioma on 18F-FDG PET/CT scans, 18F-FDG PET/CT was helpful in identifying the primary focus of the PLCs and in staging the disease. Diagnostic image interpreters should be familiar with the 18F-FDG PET/CT findings in PLC.

Comparing size evaluation methods for acoustic neuroma after stereotactic radiosurgery

PurposeAcoustic neuroma tumor size may be evaluated using several methods. Here we investigate the variations among measuring techniques.Materials and methodsA retrospective analysis of pre- and posttreatment magnetic resonance (MR) scans was performed on 15 acoustic neuroma patients with a history of stereotactic radiosurgery who had been followed for more than 2 years. Tumor size was measured on each MR scan using three methods, where the extracanalicular (EX) and intracanalicular (IN) portions were measured separately. We collected data on the largest diameter (M1), the square root of the product of the maximum anteroposterior and mediolateral diameter (M2), and the average for the maximum anteroposterior, mediolateral, and superoinferior diameters (M3). Size differences between follow-up MR scans separated by more than 2 years were calculated for each method, and we evaluated whether the tumors progressed, remained stable, or regressed.ResultsA total of 154 follow-up pairs of EX and 115 follow-up pairs of IN showed a statistically significant difference for the number of each category among the three methods (P = 0.03, P < 0.01, respectively). The greatest category agreement was observed between the M2 and M3 methods.ConclusionA significant difference between the tumor size measuring methods was observed. To strengthen specificity when evaluating tumor size difference, a measuring method using two or more parameters is recommended.

Comparison of99mTc-tetrofosmin uptakes on planar images with those in excised rats organs with those in excised rats organs

The radioactivity in the organs adjacent to the heart causes interference with the quantitative assessment of myocardial uptake of tracer on scintigraphy. In order to investigate how much the functions of these organs affect myocardial uptake seen in imaging, we compared the myocardial uptake measured by means of a gamma camera with the actual activity in the excised organs.Methods: Thirty-three rats were imaged at 5, 10, 15, 30, 45, 60, 90 and 120 min after the administration of99mTc-tetrofosmin, and % injected dose per pixel (%ID/pixel) for each organ was assessed on planar images (PI measurement). Percent injected dose per gram of tissue (%ID/g) in the heart as well as lungs, liver, gastrointestines and blood was measured by means of a well scintillation counter (WC measurement). Comparison between PI and WC measurements was performed with % uptake, the PI-to-WC ratio and heart-to-organ ratios.Results: Our WC measurement showed an increase in cardiac uptake until 30 min (1.67±0.31%) postinjection and subsequent gradual decrease, whereas PI measurement showed maximum activity of 1.81±0.52% at 15 min postinjection. There was a prominent difference between the two measurements, particularly at 10 min, with a PI/WC ratio of about 1.6 times. Our WC measurement showed maximum pulmonary uptake at 15 min (0.87±0.31%) and a gradual decrease over 15 min, whereas PI measurement showed maximum uptake at 10 min (1.14±0.38%). There was hardly any variation in activity observed later than at 10 min. Our WC measurement showed hardly any variance in hepatic activity from 5 min (0.77±0.19%) to 30 min (0.69±0.27%) with a subsequent gradual decrease. The percent uptake in PI measurement was generally greater than that in WC measurement, and high values were found at 10 min and 15 min with PI/WC ratios of about 3.3 times and 2.3 times, respectively.Conclusion: Percent uptakes in PI measurement were greater than those in WC measurement. The difference between the two measurements was prominent in the early phases. The cardiac uptake in PI measurement was significantly greater than that in WC measurement at 10 min. It was considered that this discrepancy between the two measurements was caused by the Compton scatter from the organs adjacent to the heart.

Effects of radiation on serum proteins in rabbit

Time sequential changes of various serum protein fractions of rabbits irradiated in a single dose of 800R of 60Co γ-ray, were evaluated by electrophoresis, immunoelectrophoresis and single radial immunodiffusion. The results are as follows;(1) The increase of serum albumin level was observed immediately after irradiation. However, serum albumin level decreased significantly afterwards. On the statistical analysis, significant correlation between serum albumin level and other protein fractions was recognized.(2) The significant decrease of α1-globulin level was encountered immediately following irradiation.(3) Time sequential changes of serum α2-globulin were opposite to those of serum albumin level.(4) The significant increase of β-globulin was recognized for certain period following irradiation.(5) The day of irradiation significant decrease of serum γ-globulin level was obtained in immediate and first day after irradiation.This phenomenon was thought to be related to IgG value.