Physiological uptake of 18F-fluorodeoxyglucose in uterine endometrium and myometrium: correlation with uterine motility evaluated by cine magnetic resonance imaging

BACKGROUND

Accumulation of (18)F-fluorodeoxyglucose ((18)F-FDG) in the uterine endometrium and uterine motility are dependent on menstrual cycle. However, the relationship between them remains unknown.

PURPOSE

To investigate the relationship between radiometabolic activity of (18)F-FDG in the uterus and uterine motility observed by cine magnetic resonance imaging (MRI).

MATERIAL AND METHODS

The study population consisted of 65 healthy, fertile women, selected from 229 women who underwent positron emission tomography (PET), computed tomography (CT), and MRI for cancer screening at our facility. They were divided into three groups according to their menstrual cycle phases: menstrual, follicular-periovulatory, and luteal. Regions of interest (ROIs) were placed over the endometrium and myometrium to calculate the standardized uptake value (SUV). Uterine peristalsis and contraction shown by cine MR imaging were evaluated visually, and the correlation between FDG uptake and uterine movements was assessed.

RESULTS

After excluding nine patients due to inadequate images, 56 patients (19 follicular-periovulatory, 27 luteal, and 10 menstrual) were analyzed. FDG uptake of the endometrium, frequency of peristalsis, and the presence of sustained contraction varied according to the menstruation cycle, with a tendency toward greater uptake in the menstrual phase, but there was little relationship between the frequency of uterine peristalsis and FDG accumulation in the uterus. Significantly higher FDG accumulation in the endometrium was observed in patients with sustained contractions (3.32+/-1.47) than in those without contractions (2.45+/-0.66).

CONCLUSION

Our preliminary data suggest that FDG accumulation in the endometrium tends to be higher in patients with uterine contraction, although there was no significant correlation between uterine peristalsis and FDG uptake in the uterine myometrium or endometrium.

Characterization of adipose tissue-derived cells isolated with the Celution system

BACKGROUND

The therapeutic potential of using stem cells is tremendous. Mesenchymal stromal cells (MSC) have now been isolated in various tissues including bone marrow (BM), muscle, skin and adipose tissue. Among them, adipose tissue could be one of the most suitable cell sources for cell therapy, because of its easy accessibility, minimal morbidity and abundance of stem cells. The large numbers of stem cells in adipose tissue means that clinically relevant stem cell numbers could be extracted from the tissue, potentially eliminating the need for in vitro expansion. To utilize these characteristics of adipose tissue fully, Cytori Therapeutics Inc. has developed a closed system called Celution to isolate and concentrate stem cells and regenerative cells automatically from adipose tissue.

METHODS

Adipose tissue-derived cells were isolated using the Celution system. The output from the Celution was characterized using multicolor FACS analysis with CD31, CD34, CD45, CD90, CD105 and CD146. The multidifferentiation potential of the cells was analyzed using adipogenic and osteogenic media.

RESULTS

Our results showed that cells from the Celution are composed of heterogeneous cell populations including adipose-derived stem cells (ASC) (CD31- CD34+ CD45- CD90+ CD105- CD146-), endothelial (progenitor) cells (CD31+ CD34+ CD45- CD90+ CD105- CD146+) and vascular smooth muscle cells (CD31- CD34+ CD45- CD90+ CD105- CD146+). We also confirmed the output contains cells able to differentiate into adipogenic and osteogenic phenotypes. Our results show that cells isolated with the Celution and manually are equivalent.

DISCUSSION

Cells from adipose tissue can be processed by Celution within the time frame of a single surgical procedure. This system could provide a 'real-time' treatment setting that is cost-effective and safe.

[Indication for limited surgery on small lung cancer tumors measuring 1cm or less in diameter on preoperative computed tomography and long-term results]

OBJECTIVE

Non-invasive lung cancers showed a good prognosis after limited surgery. But it is still uncertain about invasive lung cancers. We investigated the indications for limited surgery for small lung cancer tumors measuring 1 cm or less in diameter on preoperative computed tomography (CT).

METHODS

This study retrospectively analyzed of 1,245 patients who underwent complete resection of lung cancer between 1989 and 2004 in our hospital. Sixty-two patients (5%) had tumors measuring 1 cm or less in diameter. The probability of survival was calculated using the Kaplan-Meier method.

RESULTS

All diseases were detected by medical checkup, 52 % of the patients were not definitively diagnosed with lung cancer before surgery. Adenocarcinoma was histologically diagnosed in 49 patients (79%). Other histologic types included squamous cell carcinoma (8), large cell carcinoma (1), small cell carcinoma (1), carcinoid (2), and adenosquamous cell carcinoma (1). Fifty-seven patients (92%) showed pathologic stage IA. The other stages were IB (2), IIA (1), and IIIB (2). There were 14 bronchioloalveolar carcinomas (25% of IA diseases). The 5-year survival rates of IA patients were 90%. The 5-year survival rate of patients with tumors measuring 1cm or less diameter was 91% after lobectomy or pneumonectomy, and 90% after wedge resection or segmentectomy. There were 3 deaths from cancer recurrence, while there were no deaths in 14 patients with bronchioloalveolar carcinoma

CONCLUSION

After limited surgery, non-invasive cancer showed good long-term results, while invasive cancer showed a recurrence rate of 2.3% to 79% even though the tumor measured 1 cm or less in diameter on preoperative CT.

Genetic improvement of total milk yield and total lactation persistency of the first three lactations in dairy cattle

The objective of this study was to compare 6 selection criteria in terms of 3-parity total milk yield and 9 selection criteria in terms of total net merit (H) comprising 3-parity total milk yield and total lactation persistency. The 6 selection criteria compared were as follows: first-parity milk estimated breeding value (EBV; M1), first 2-parity milk EBV (M2), first 3-parity milk EBV (M3), first-parity eigen index (EI(1)), first 2-parity eigen index (EI(2)), and first 3-parity eigen index (EI(3)). The 9 selection criteria compared in terms of H were M1, M2, M3, EI(1), EI(2), EI(3), and first-parity, first 2-parity, and first 3-parity selection indices (I(1), I(2), and I(3), respectively). In terms of total milk yield, selection on M3 or EI(3) achieved the greatest genetic response, whereas selection on EI(1) produced the largest genetic progress per day. In terms of total net merit, selection on I(3) brought the largest response, whereas selection EI(1) yielded the greatest genetic progress per day. A multiple-lactation random regression test-day model simultaneously yields the EBV of the 3 lactations for all animals included in the analysis even though the younger animals do not have the opportunity to complete the first 3 lactations. It is important to use the first 3 lactation EBV for selection decision rather than only the first lactation EBV in spite of the fact that the first-parity selection criteria achieved a faster genetic progress per day than the 3-parity selection criteria. Under a multiple-lactation random regression animal model analysis, the use of the first 3 lactation EBV for selection decision does not prolong the generation interval as compared with the use of only the first lactation EBV. Thus, it is justified to compare genetic response on a lifetime basis rather than on a per-day basis. The results suggest the use of M3 or EI(3) for genetic improvement of total milk yield and the use of I(3) for genetic improvement of total net merit H. Although this study deals with selection for 3-parity milk production, the same principle applies to selection for lifetime milk production.

T1 signal intensity and height of the anterior pituitary in neonates: correlation with postnatal time

BACKGROUND AND PURPOSE

The anterior pituitary of a term neonate is usually hyperintense on T1-weighted MR images, which may represent histologic changes of the gland due to the effect of high estrogen levels during the fetal period; however, MR findings of a preterm neonate have not been fully evaluated. The purpose of this study was to investigate whether intensity and size of the neonatal anterior pituitary on MR images obtained near term of corrected age correlates with the gestational age at birth or postnatal time.

MATERIALS AND METHODS

Data of 88 consecutive neonates (gestational age, 24-41 weeks; mean, 31.5 weeks) were analyzed. All of the neonates underwent MR imaging at a corrected age of 0 months +/- 4 weeks. Relative signal intensity of the anterior pituitary compared with that of the pons on T1-weighted sagittal images was calculated. Height of the pituitary was also measured. Stepwise regression analysis was performed to evaluate the effects of gestational age at birth and postnatal time on the relative signal intensity and on the pituitary height.

RESULTS

The relative signal intensity significantly negatively correlated with postnatal time (P = .001) but not with gestational age at birth (P = .42). Pituitary height significantly negatively correlated with postnatal time (P = .049) but not with gestational age at birth (P = .071).

CONCLUSION

A significant negative correlation exists between postnatal time and signal intensity on T1-weighted MR images of the anterior pituitary obtained near term. A nonhyperintense anterior pituitary is a normal MR finding of preterm neonates when imaged near term.

[Primary spontaneous pneumomediastinum]

We report 5 cases of spontaneous pneumomediastinum. They were 4 men and 1 female with a mean age of 17 (14-25). Four patients developed sport-related pneumomediastinum and 1 patient had a karaoke-related condition. Primary spontaneous pneumomediasinum is a rare condition. In addition, there is no previous report describing karaoke-related spontaneous pneumomediastinum. Each of the patients experienced chest pain and/or neck pain before consulting our hospital. Chest roentgenogram and chest computed tomography showed pneumomediastinum without esophageal or tracheal injury. Four patients did not require hospitalization, but 1 patient was necessary to hospitalize for 7 days because of severe chest and neck pain. None of these 5 patients has had any recurrence for more than 1 year. Differentiating this entity from other diseases involving anterior chest pain is important.

Diffusion tensor fiber tractography for arteriovenous malformations: quantitative analyses to evaluate the corticospinal tract and optic radiation

BACKGROUND AND PURPOSE

We hypothesized that diffusion tensor fiber tractography would be affected by intracranial arteriovenous malformation (AVM). The purpose of the present study was to evaluate the influence of intracranial AVM on corticospinal tract and optic radiation tractography.

MATERIALS AND METHODS

The subject group comprised 34 patients with untreated intracranial AVM. Hemorrhage was present in 13 patients and absent in 21 patients. Perinidal fractional anisotropy (FA) and number of voxels along the reconstructed corticospinal and optic radiation tracts were measured, and left-to-right asymmetry indices (AIs) for those values were quantified. Patients were assigned to 1 of 3 groups: tracts distant from nidus, tracts close to nidus without neurologic symptoms, and tracts close to nidus associated with neurologic symptoms. One-way analysis of variance was used to compare differences in AI between groups. Hemorrhagic and nonhemorrhagic groups were assessed separately.

RESULTS

In patients without hemorrhage, AI of optic radiation volume (P<.0001), AI of perinidal FA along corticospinal tract (P=.006), and optic radiation (P=.01) differed significantly between groups. In patients associated with hemorrhage, AI of corticospinal tract volume (P=.01), AI of perinidal FA along corticospinal tract (P=.04), and optic radiation (P=.004) differed significantly between groups.

CONCLUSIONS

Corticospinal tract and optic radiation tractography were visualized in patients with AVM. In patients with both hemorrhagic and nonhemorrhagic AVM, the 2 fiber tracts close to the nidus were less visualized in the affected hemisphere than those distant from the nidus. Tracts were less visualized in patients with neurologic symptoms than in asymptomatic patients.

[Sarcomatoid pleural mesothelioma presenting as posterior mediastinal tumor with dysphagia]

Case 1: A 46-year-old man with dysphagia, chest pain and cough admitted to our department. Radiological studies demonstrated a solid mass with a maximal diameter of 5cm at the posterior mediastinum. The tumor was resected, then postoperative radiotherapy (60Gy) and chemotherapy were performed. Results of histological and immunohistochemical study showed that the tumor consisted of sarcomatoid mesothelioma. The patient died of recurrence with bone metastasis 6 months after surgery. Case 2: A 76-year-old man with dysphagia, chest pain and cough admitted to our department Radiological studies demonstrated a solid mass with a maximal diameter of 12cm in the posterior mediastinum. accompanied by abundant effusion in the bilateral pleural cavities. The patient underwent open biopsy and histological and immunohistochemical study showed that the tumor consisted of sarcomatoid mesothelioma. The patient died of multiple organ failure on the 1st postoperative day. We report extremely rare cases of sarcomatoid mesothelioma that appeared to be posterior mediastinal tumor before surgery, and discuss the difficulty of diagnosing sarcomatoid mesothelioma with atypical clinical manifestations.

Diffusion tensor fiber tractography of the optic radiation: analysis with 6-, 12-, 40-, and 81-directional motion-probing gradients, a preliminary study

BACKGROUND AND PURPOSE

Knowing the exact location of the optic radiation preoperatively is important for surgery of the temporal lobe. We hypothesized that a greater number of motion-probing gradients (MPGs) would provide better results of diffusion tensor (DT) fiber tractography of the optic radiation. To test this hypothesis, this study evaluated differences in DT fiber tractography of the optic radiation under different MPG settings.

METHODS

DT images were obtained in 12 healthy volunteers (7 men, 5 women) with a mean age of 32 years (range, 22-45 years) by using a 3T MR imaging scanner with single-shot echo-planar imaging with parallel acquisition (reduction factor = 2). MPG was applied in 6, 12, 40, and 81 independent directions. The first region of interest (ROI) was placed in the occipital lobe, and the second ROI was placed in the lateral geniculate body. Fibers penetrating both ROIs were considered as the optic radiation. Anteroposterior distance between the tip of the Meyer loop and the lateral geniculate body on an axial section was defined as a loop index. Numbers of fibers and loop indices in both cerebral hemispheres were evaluated statistically.

RESULTS

The optic radiation was well visualized in full length by DT fiber tractography in 20 of 24 hemispheres (83%). No significant differences were noted in number of fibers and loop indices among different MPG settings.

CONCLUSION

DT fiber tractography can frequently depict almost the entire optic radiation. MPG number does not exert any significant effect on visualization of the optic radiation, and 6-directional MPG is thus sufficient for this purpose.

Selection for Milk Production and Persistency Using Eigenvectors of the Random Regression Coefficient Matrix

The purpose of this study was to investigate the relationships of the eigenvectors of the additive genetic random regression coefficient matrix (K) to selection responses and to determine how many eigenvectors are necessary in the breeding goal to explain the variation. The construction of various eigenvector indexes was based on the K matrix estimated from test-day records of Japanese Holstein cattle. The first (leading) eigenvector index produced constant responses for each day of lactation, indicating that the first eigenvector is responsible for scaling the lactation curve without altering its shape. Daily genetic responses to the second eigenvector index increased linearly as DIM increased. Genetic responses to the third eigenvector index were negative in mid-lactation but were positive in early and late lactation (concave curve). Genetic responses to the fourth and fifth eigenvector indexes hovered around zero across the lactation. The results suggest that both second and third eigenvectors account for the change in the shape of the lactation curve and there is little utility of the fourth and fifth eigenvectors in improving lactation milk or persistency. When the goal is to increase lactation milk yield alone, the index based on the first eigenvector produced a similar response to the index based on all 5 eigenvectors. When the goal is to improve both lactation milk yield and persistency, the index based on the first 3 eigenvectors achieved more than 99.9% of the genetic response to an index based on all 5 eigenvectors. The advantage of an eigenvector index over conventional selection based on total lactation milk yield increases with increasing economic weight assigned to persistency.

Metastatic lymph nodes in urogenital cancers: contribution of imaging findings

The presence of nodal metastasis in patients with urogenital malignancies is an important factor for prognosis, and radiologic identification of enlarged nodes greatly affects treatment choices. Radiologic evaluation for nodal metastases is usually performed with computed tomography, but magnetic resonance imaging is also useful in evaluating primary and nodal metastases in pelvic tumors. On these cross-sectional modalities, nodal metastases are usually suspected according to location and size criteria. Although there has been no general consensus on the criteria, a short axis diameter of 8 to 10 mm is generally applied. However, radiologic evaluation does not always provide sufficient accuracy for nodal staging because of an inability to diagnose smaller metastatic lymph nodes. The clinical significance of a radiologic recognition of enlarged nodes also differs by cancer type in relation to differences in staging systems and treatment. The presence of regional lymphadenopathy in patients with renal cell carcinoma often alters surgical methods, whereas the presence of regional lymphadenopathy is an indication of systemic chemotherapy in patients with cancers of the urinary tract, prostate, and testicles. In this report, preferential sites and staging of nodal metastasis and contributions of radiologic imaging are reviewed for each urogenital cancer.

The use of acetic acid in magnification chromocolonoscopy for pit pattern analysis of small polyps

BACKGROUND AND STUDY AIMS

The role of acetic acid spray during magnification chromocolonoscopy has not previously been evaluated. We aimed to compare the accuracy of predicting polyp histology at magnification colonoscopy, using acetic acid and indigo carmine, either alone or in combination.

PATIENTS AND METHODS

A total of 46 consecutive patients with polyps detected during colonoscopy which measured 10 mm or less were alternately divided into two groups. In group A patients, 1.5 % acetic acid was applied to the mucosa first, followed by indigo carmine spray; in group B patients, the order was reversed. The pit pattern was assessed after application, in real time. All the lesions were resected and examined histologically.

RESULTS

Altogether, 37 adenomas and 36 hyperplastic polyps were evaluated. In group A, the diagnostic accuracy after spraying with acetic acid was 95 %, which increased to 98 % after application of indigo carmine. In group B, the accuracy after indigo carmine application was 83 %. After subsequent spraying with acetic acid, images were enhanced in 70 % of patients, with an increase in accuracy to 97 %. The mean time required to obtain an initial clear image with the first dye was 14 seconds for both groups.

CONCLUSIONS

This is the first description of the use of acetic acid for pit pattern analysis of colonic polyps. Its ease of use, low cost, and safety, together with its excellent accuracy in the assessment of polyp pit patterns suggest that this method could easily be applied to routine magnification colonoscopy.

Frequent involvement of ras-signalling pathways in both polypoid-type and flat-type early-stage colorectal cancers

The development of colorectal neoplasms proceeds mainly via the adenoma-carcinoma sequence. BRAF and RASSF1A are members of Ras-signaling pathways, but the roles of their aberrations in colorectal carcinogenesis remain unclear. The authors studied mutations of the BRAF and K-ras genes, RASSF1A promoter methylation, and p53 overexpression in 43 polypoid-type and 30 flat-type early-stage colorectal cancers. No tumor simultaneously showed any combination of K-ras mutations, BRAF mutations, and RASSF1A promoter methylation. Three of the 73 tumors (4.1%) had BRAF mutations. All BRAF mutation-positive tumors were flat-type cancers, not associated with coexisting adenoma or p53 overexpression. RASSF1A promoter methylation was detected in 12 out of 73 tumors (16.4%), and the proportion of positive cases was similar in polypoid-type and flat-type cancers. BRAF mutations, K-ras mutations, and RASSF1A promoter methylation independently participate in early-stage colorectal carcinogenesis. BRAF mutations are involved only in flat-type cancers, whereas RASSF1A promoter methylation is involved in both polypoid-type and flat-type cancers. Thus, BRAF mutations most likely participate in de novo colorectal carcinogenesis, K-ras mutations in the adenoma-carcinoma sequence of colorectal carcinogenesis, and RASSF1A promoter methylation in both cascades.

[Long-term prognosis after surgery for pathological stage III lung cancer]

OBJECTIVE

We studied for the purpose of revealing the long-term prognosis of the surgical treatment for pathological stage III lung cancer.

METHOD

Two hundred fifty-four patients with pathological stage III disease who underwent surgical procedures in our hospital from 1981 to 2000 were investigated retrospectively.

RESULTS

The 5- and 10-year survival rates of 144 patients with stage IIIA disease were 35 and 25%, while those of 110 patients with IIIB disease were 30 and 16%. The 5- and 10-year survival rates were 40 and 27% for 52 patients with T1N2 disease, 33 and 23% for 70 patients with T2N2 disease, 34 and 0% for 9 patients with T3N1 disease, and 33 and 26% for 13 patients with T3N2 disease, respectively. In the patients with IIIB disease, the 5- and 10-year survival rates of 56 patients only with pml were 47 and 26%, those of the other patients were 9 and 0%. There is significant difference among them (p < 0.0001). In 54 patients with IIIB disease in addition to pm1, the 5-year survival rates of 19 patients with exploration only and the other patients were 7 and 14%, respectively. There were no 10-year survivors in both groups.

CONCLUSION

The long-term prognosis of pathological stage III disease was still not satisfactory. Therefore, we should make efforts to get a sufficient informed-consent before the surgery for the patients with stage III disease.

[Ultrasound carotid artery plaque morphology and perioperative stroke risk in patients undergoing coronary artery bypass grafting]

OBJECTIVE

To determine the influence of carotid artery plaque (CAP) morphology on perioperative stroke in coronary artery bypass grafting (CABG).

PATIENTS AND METHODS

Ninety-three patient undergoing CABG were studied. CAPs and other lesions including intima-media thickness (IMT) and stenosis were examined by using ultrasound imaging. CAPs were morphologically classified as either homogeneous (HmP) or heterogeneous (HtP).

RESULTS

Mean and max IMT were 1.26 +/- 0.15 and 2.44 +/- 0.76 mm. Mean total plaque score was 15.75 +/- 6.82. HmP and HtP were seen in 80 (86.0%) and 54 (58.1%) patients. Stenosis greater than 50% was found in 22 (23.7%) patients. HtP was significantly associated with age (p<0.05), diabetes and severity of coronary artery disease (p<0.01) and stenosis was associated with diabetes and history of cerebrovascular events (p <0.05). Late postoperative stroke occurred in 3 (3.2%) patients during hospitalization. One of them had 90% stenosis in the carotid artery. The others had no carotid stenosis. In all of the 3, the predominant plaques were heterogeneous.

CONCLUSION

CAP morphology in patients undergoing CABG was detailed. As well as stenotic lesion, plaque heterogeneity may be a risk factor for perioperative stroke. Diabetes is associated with severity of both plaque heterogeneity and stenosis.

Ectopically located gonads in a patient with mixed gonadal dysgenesis: detection by diffusion-weighted MRI

We report a case of mixed gonadal dysgenesis in which diffusion-weighted magnetic resonance imaging played a major role in the detection of ectopically located gonads. Magnetic resonance imaging may have a potential in detecting ectopically located gonads and may provide important information for the management of patients with mixed gonadal dysgenesis.

Maximization of Lactation Milk Production Without Decreasing Persistency

This study treats each daily estimated breeding value (EBV) of the lactation as a separate trait to modify the lactation curve on a daily basis. Six selection strategies for improving lactation milk without decreasing persistency were compared: 1) index I(R1), subject to the restriction of equal genetic gains at days in milk (DIM) 60 and 280, 2) I(R2), subject to the restriction of zero gain at DIM 60, 3) desired gains index I(d), designed to increase lactation milk without altering the lactation curve, 4) index I(u), comprising lactation EBV and persistency without standardization, 5) index I(w), consisting of lactation EBV (EBV(L)) and persistency with standardization, and 6) conventional selection on EBV(L) and used as a basis for comparison. Of the 6 selection strategies compared, I(R2) yielded the greatest persistency, but achieved the smallest response in EBV(L), suggesting that it is impractical to increase persistency by inhibiting change in the peak yield. Index I(u) showed the same response in lactation milk as conventional selection on EBV(L), but resulted in the same decreased persistency. Although both I(R1) and I(d) achieved constant persistency, the former produced a greater lactation response (669 kg EBV) than the latter (560 kg EBV). Thus, I(R1) is a viable strategy for improving EBV(L) while holding persistency constant. None of the 6 selection strategies excelled in both lactation milk and persistency. Index I(w) appears to be a reasonable choice for improving both traits, although responses would depend on the relative economic importance of the 2 traits. Differential responses between I(u) and I(w) emphasize the need to weight the EBV of different traits by the inverse of their standard deviations in index construction when the EBV vary widely in variance. The general formula developed here provides a useful genetic means of modifying the lactation curve by restricting differential genetic gains among different days of the lactation.

[Tetraplegia and respiratory failure due to carcinomatous neuropathy in the early postoperative period of a lung cancer patient: report of a case]

A 63-year-old man, with atypical pulmonary mycobacteriosis and also with hepatic dysfunction due to chronic hepatitis C, underwent wedge resection of the right lower lobe for non-small cell lung cancer. On the 9th postoperative day, the patient developed acute tetraplegia and then respiratory failure. Neither computed tomography (CT) nor magnetic resonance imaging (MRI) of brain and cervical vertebrae showed any cancer metastases. The neurological symptoms were those of Guillain-Barre syndrome. Therefore, we speculate that the cause of the neuromyopathy might be autoimmune antibodies from lung cancer. Steroid pulse therapy and plasma exchange treatment were effective and the patient's symptoms disappeared in a month. We reported the extremely rare case of a lung cancer patient with acute tetraplegia in the early postoperative period.

Elastic moduli of thyroid tissues under compression

The aim of this study was to evaluate the elastic moduli of thyroid tissues under uniaxial compression and to establish the biomechanical fundamentals for accurate interpretation of thyroid elastograms. A total of 67 thyroid samples (24 samples of normal thyroid tissue, 2 samples of thyroid tissue with chronic thyroiditis, 12 samples of adenomatous goiter lesions and 7 samples of follicular adenoma, 19 samples of papillary adenocarcinoma (PAC) and 3 samples of follicular adenocarcinoma (FAC)) obtained from 36 patients who had received thyroid surgery were subjected to biomechanical testing within three hours after surgical resection at precompression strains of 5%, 10% and 20% and applied strains of 1%, 2%, 5% and 10% of sample height. As a result, the mean values of elastic moduli for benign thyroid lesions at all examined precompression levels were significantly higher than those for normal thyroid tissue measured at the same load (p<0.01). At low precompression (5%) and compression (1-2%) levels, benign thyroid nodule samples were 1.7 times harder than normal thyroid tissue. At high precompression (20%) and compression (10%) levels, this difference increased to 2.4 times. Stiffness of PAC samples was significantly higher than those for normal thyroid tissue and benign thyroid tumors measured at the same load (p<0.01). At low precompression (5%) and compression (1-2%) levels, PAC samples were 5.0 times harder than normal thyroid tissue. At high precompression (20%) and compression (10%) levels, this difference increased to 17.7 times. In contrast, samples of FAC were much softer than PAC (p<0.05) and were comparable in stiffness to normal thyroid tissues. The significant differences in the stiffness between normal thyroid tissue and thyroid tumors may provide useful information for accurate interpretation of thyroid elastograms.