Endoscopic thyroidectomy using the EZ-VANS method

Purpose

Several video-assisted and robotic surgery techniques have been reported for resection of the thyroid and parathyroid glands. Our institute has started performing endoscopic thyroidectomy using the Lap-protector and E·Z-access system, referred to as E·Z-access using video-assisted neck surgery (EZ-VANS). In this report, we evaluate the safety and efficacy of this technique.

Methods

From January 2007 to September 2014, 110 patients underwent resection of a primary thyroid tumor, 73 who underwent a cervical collar incision (the Open group) and 37 underwent EZ-VANS (the EZ-VANS group).

Results

The average operating time was 159 and 172 min in the Open group and EZ-VANS group, respectively; the amount of blood loss was 46.5 and 54.7 ml, respectively; and the length of hospital stay after surgery was 4.3 and 5.2 days, respectively, with no significant differences observed between the two groups. The learning curve for the EZ-VANS technique was shorter than for open surgery.

Conclusions

We confirmed that the EZ-VANS technique is a safe and useful method for resection of benign and early malignant thyroid tumors.

     

Survey of volume CT dose index in Japan in 2014

Objective:

The aims of this study are to propose a new set of Japanese diagnostic reference levels (DRLs) for 2014 and to study the impact of tube voltage and the type of reconstruction algorithm on patient doses. The volume CT dose index (CTDI_vol) for adult and paediatric patients is assessed and compared with the results of a 2011 national survey and data from other countries.

Methods:

Scanning procedures for the head (non-helical and helical), chest and upper abdomen were examined for adults and 5-year-old children. A questionnaire concerning the following items was sent to 3000 facilities: tube voltage, use of reconstruction algorithms and displayed CTDI_vol.

Results:

The mean CTDI_vol values for paediatric examinations using voltages ranging from 80 to 100 kV were significantly lower than those for paediatric examinations using 120 kV. For adult examinations, the use of iterative reconstruction algorithms significantly reduced the mean CTDI_vol values compared with the use of filtered back projection. Paediatric chest and abdominal scans showed slightly higher mean CTDI_vol values in 2014 than in 2011. The proposed DRLs for adult head and abdominal scans were higher than those reported in other countries.

Conclusion:

The results imply that further optimization of CT examination protocols is required for adult head and abdominal scans as well as paediatric chest and abdominal scans.

Advances in knowledge:

Low-tube-voltage CT may be useful for reducing radiation doses in paediatric patients. The mean CTDI_vol values for paediatric scans showed little difference that could be attributed to the choice of reconstruction algorithm.Since the introduction of CT in the 1970s, it has been established worldwide as one of the most important imaging modalities in diagnostic radiology. In the past decade, various dose-reduction techniques, such as tube current modulation¹ and low tube voltage,² have been shown to reduce radiation exposure. In particular, the use of an iterative reconstruction (IR) algorithm, in contrast to a filtered back projection (FBP) algorithm, has provided diagnostically acceptable images using low-radiation-dose CT.^3,4Since estimates of the cancer risk attributable to the use of diagnostic X-rays have been reported,^5,6 radiological technologists should aim to optimize scan parameters in order to avoid excessive radiation exposure. One powerful tool in this optimization applies the concept of diagnostic reference levels (DRLs). The DRLs of CT examinations are generally expressed in terms of the volume CT dose index (CTDI_vol) or dose–length product. The DRL is used in medical imaging with ionizing radiation to indicate whether, in routine conditions, the patient dose from a specified procedure is unusually high or low; DRLs are usually reviewed at regular intervals and could be specific to a country or region.⁷ Surveys of DRLs for CT examination of adults^8–11 and children^12,13 have been reported in several countries.The current DRLs in Japan were established as target values by the Japan Association of Radiological Technologists in 2006. The DRLs refer to a set of medical exposure guidelines, although there are several issues with these guidelines.¹⁴ First, no more than two examinations (head and abdomen) are listed in DRLs, and they contain no information about the CT examination of children. Second, the DRL for abdomen examination employs a 30-cm phantom, whereas a 32-cm phantom is more commonly used worldwide. Therefore, a new set of Japanese DRLs has become an urgent necessity. In 2011, Asada et al¹⁵ reported mean CTDI_vol values for the head (non-helical and helical), chest and upper abdomen of both adults and children, which were obtained using a nationally distributed questionnaire. The aims of this study are to propose a new set of Japanese DRLs for 2014 and to study the impact of tube voltage and the type of reconstruction algorithm on patient doses. The CTDI_vol for both adults and children have been assessed and compared with both the results of the 2011 survey and data from other countries.     

Relative preservation of peripheral lung function in smoking-related pulmonary emphysema: assessment with 99mTc-MAA perfusion and dynamic 133Xe SPET

In this study the cross-sectional functional differences between the central and peripheral lung in smokers with pulmonary emphysema were evaluated by lung perfusion and dynamic xenon-133 single-photon emission tomography (SPET). The subjects were 81 patients with a long-term smoking history and relatively advanced emphysema, 17 non-smoker patients with non-obstructive lung diseases and six healthy non-smokers. Regional lung functional difference between the peripheral and central lung was assessed in the upper, middle and lower lung zones by technetium-99m macroaggregated albumin SPET and dynamic ¹³³Xe SPET. The distribution of emphysematous changes was assessed by density-mask computed tomography (CT) images which depicted abnormally low attenuation areas (LAAs) of less than –960 Hounsfield units. Two hundred and eighty-eight (59.2%) lung zones of 63 (77.7%) patients with pulmonary emphysema showed relative preservation of lung function in the peripheral lung, with a curvilinear band of normal perfusion (a stripe sign) and a significantly faster ¹³³Xe half-clearance time (T _1/2) than in central lung (P<0.0001). Of these lung zones, 256 (88.8%) showed central-dominant LAA distributions on density-mask CT images, but the remaining 32 zones did not show any regional preference in LAA distribution. Conversely, 117 (24.0%) lung zones of 19 (23.4%) patients showed periphery-dominant perfusion defects and LAA distributions, with significantly prolonged T _1/2 in the peripheral lung area (P<0.0001). The remaining 81 lung zones of the patients with pulmonary emphysema and all the lung zones of the healthy subjects and patients with non-obstructive lung diseases did not show a stripe sign, and no differences were observed in T _1/2 values and LAA distributions between the central and peripheral lung. Relative preservation of peripheral lung function seems to be a characteristic feature in smoking-related pulmonary emphysema, and may indicate a lower susceptibility of peripheral parenchyma to the development of this disease. Received 8 January and in revised form 13 March 2000     

Relative preservation of peripheral lung function in smoking-related pulmonary emphysema: assessment with 99mTc-MAA perfusion and dynamic 133Xe SPET

In this study the cross-sectional functional differences between the central and peripheral lung in smokers with pulmonary emphysema were evaluated by lung perfusion and dynamic xenon-133 single-photon emission tomography (SPET). The subjects were 81 patients with a long-term smoking history and relatively advanced emphysema, 17 non-smoker patients with non-obstructive lung diseases and six healthy non-smokers. Regional lung functional difference between the peripheral and central lung was assessed in the upper, middle and lower lung zones by technetium-99m macroaggregated albumin SPET and dynamic 133Xe SPET. The distribution of emphysematous changes was assessed by density-mask computed tomography (CT) images which depicted abnormally low attenuation areas (LAAs) of less than -960 Hounsfield units. Two hundred and eighty-eight (59.2%) lung zones of 63 (77.7%) patients with pulmonary emphysema showed relative preservation of lung function in the peripheral lung, with a curvilinear band of normal perfusion (a stripe sign) and a significantly faster 133Xe half-clearance time (T(1/2)) than in central lung (P<0.0001). Of these lung zones, 256 (88.8%) showed central-dominant LAA distributions on density-mask CT images, but the remaining 32 zones did not show any regional preference in LAA distribution. Conversely, 117 (24.0%) lung zones of 19 (23.4%) patients showed periphery-dominant perfusion defects and LAA distributions, with significantly prolonged T(1/2) in the peripheral lung area (P<0.0001). The remaining 81 lung zones of the patients with pulmonary emphysema and all the lung zones of the healthy subjects and patients with non-obstructive lung diseases did not show a stripe sign, and no differences were observed in T(1/2) values and LAA distributions between the central and peripheral lung. Relative preservation of peripheral lung function seems to be a characteristic feature in smoking-related pulmonary emphysema, and may indicate a lower susceptibility of peripheral parenchyma to the development of this disease.     

An aggressive course of Xp11 translocation renal cell carcinoma in a 28-year-old man

Abstract:   Cases of renal cell carcinoma (RCC) associated with Xp11 translocations are rare and are reported predominantly in children. We report a case of a young man who developed an aggressive Xp11 translocation RCC. A 28-year-old man presented with back pain, fever and macroscopic hematuria. Computed tomography of the abdomen showed a heterogeneous mass in the left kidney. Left radical nephrectomy was performed. Hematoxylin–eosin staining revealed nested and papillary architecture, clear and eosinophilic cytoplasm and vesicles with prominent nucleoli. Immunohistochemical evaluation revealed that the tumor cells showed nuclear labeling for TFE3 protein. On the basis of these findings, the case was diagnosed as Xp11 translocation RCC. This tumor massively recurred and led to the patient's death 2 years after the initial diagnosis. The utility of immunohistochemistry using antibodies against TFE3 in RCC occurring in young adults may be necessary for accurate diagnosis.     

Motion artifact reduction of diffusion‐weighted MRI of the liver: Use of velocity‐compensated diffusion gradients combined with tetrahedral gradients

Purpose:

To assess the effect of motion artifact reduction on the diffusion‐weighted magnetic resonance imaging (DWI‐MRI) of the liver, we compared velocity‐compensated DWI (VC‐DWI) and VC‐DWI combined with tetrahedral gradients (t‐VC‐DWI) to conventional DWI (c‐DWI) in the assessment of apparent diffusion coefficients (ADCs) of the liver.

Materials and Methods:

In 12 healthy volunteers, the liver was scanned with c‐DWI, VC‐DWI, and t‐VC‐DWI sequences. The signal‐to‐noise ratio (SNR) and ADC of the liver parenchyma were measured and compared among sequences.

Results:

The image quality was visually better for t‐VC‐DWI than for the others. The SNR for t‐VC‐DWI was significantly higher than that for VC‐DWI (P < 0.05) and comparable to that for c‐DWI. ADCs in both hepatic lobes were significantly lower for t‐VC‐DWI than for c‐DWI (P < 0.01). ADC in the left lobe was significantly lower for VC‐DWI than for c‐DWI (P < 0.01). Although ADC in the left lobe was significantly higher for c‐DWI (P < 0.01), no significant differences in ADCs were found between the right and left lobes for VC‐DWI and t‐VC‐DWI.

Conclusion:

The use of a t‐VC‐DWI sequence enables us to correct ADCs of the liver for artificial elevation due to cardiac motion, with preserved SNR. J. Magn. Reson. Imaging 2013;37:172–178. © 2012 Wiley Periodicals, Inc.     

Improved reproducibility of simple quantitative indices from 99mTc-GSA liver functional imaging

Objective

We evaluated intra- and interoperator reproducibilities in calculating the conventional indices HH15 and LHL15 from ^99mTc-diethylenetriamine pentaacetic acid galactosyl human serum albumin (^99mTc-GSA) scintigraphy, and proposed new, simple methods for the calculation of quantitative indices.

Methods

The results of ^99mTc-GSA scintigraphy in 33 patients were retrospectively analyzed. Heart and liver ROIs were drawn manually to cover cardiac blood pool and entire liver, respectively, and HH15 and LHL15 were calculated. In addition, square regions of interest (ROIs) of fixed sizes were placed at the highest activity in blood pool and the liver. Using the square heart ROI, sHH15, an equivalent of HH15, was computed. Fractional liver uptake at 15 min (FLU15) was calculated using the square heart and liver ROIs. Intra- and interoperator reproducibilities, as well as correlation with Indocyanine green retention rate at 15 min (ICG R15), were assessed for these four indices by linear regression analysis.

Results

Substantial intra- and interoperator variabilities were found for HH15 and LHL15. The correlation coefficients for intra- and interoperator comparisons were 0.884 and 0.869 for HH15, respectively, and 0.919 and 0.917 for LHL15, respectively. The use of square ROIs instead of hand-drawn ROIs improved reproducibility. The correlation coefficients for intra- and interoperator comparisons were 0.988 and 0.973 for sHH15, respectively, and 0.989 and 0.975 for FLU15, respectively. Correlation with ICG R15 was better for sHH15 (r = 0.619) and FLU15 (r = ?0.656) than for HH15 (r = 0.439) and LHL15 (r = ?0.490).

Conclusions

HH15 and LHL15 showed substantial intra- and interoperator variabilities, and the use of square ROIs are indicated to provide better reproducibility.