Search

We evaluated the effects on the absorbed dose to thyroid follicular cells of self-absorption of 131I radiation (specifically, β-rays) in the follicular colloid. Methods: Thyroid follicles were modeled as colloid-filled spheres, containing a uniform concentration of 131I and surrounded by a concentric monolayer of cells. Assuming close packing of identical follicles, we used Monte Carlo simulation to assess the absorbed dose to follicular cells. Results: Because of β-ray self-absorption in colloidal spheres with radii larger than 50 μm, the absorbed dose to follicular cells is less than the average thyroid absorbed dose. Conclusion: For the same thyroid mass, radioiodine thyroid uptake, and effective half-life, patients with follicles with colloidal sphere radii of 100, 200, 300, and 400 μm should be administered 9%, 15%, 21%, and 30% more 131I, respectively, than patients with colloidal sphere radii of less than 50 μm, to yield the same absorbed dose to follicular cells.

Context: Despite accounting for variations in gland size and iodine kinetics, the success of radioiodine therapy in patients with Graves’ disease remains moderately common and unpredictable. Objectives: We hypothesized that hypoechogenic glands, with large, densely packed cells, are more radiosensitive than normoechogenic glands, in which much radiation is wasted on more abundant colloid. We evaluated this hypothesis in a cohort of patients with Graves’ disease. Design: This was a prospective trial of patients recruited during 4 yr and followed up 1 yr after radioiodine therapy. Setting: This trial was held in a university hospital-outpatient clinic. Patients: A total of 177 consecutive patients with first presentation of Graves’ disease (28 males), 23–76 yr old, who relapsed after antithyroid therapy were included in the study. Intervention: The patients were assigned to an ablative target-absorbed dose of 200 Gy (n = 78) or randomly to 100 or 120 Gy of nonablative dose (n = 99). Main Outcome Measures: The measures were incidences of hyperthyroidism, euthyroidism, and hypothyroidism at 12-month follow-up. Results: At follow-up there were 25 hyperthyroid, 44 euthyroid, and 108 hypothyroid patients. Compared with 96 patients with a hypoechogenic gland, in 81 patients with a normoechogenic gland, there were more hyperthyroid (22 vs. 7%) and euthyroid (41 vs. 11%), but less hypothyroid outcomes (37 vs. 81%; P < 0.0001). The other independent predictor of increased radioresistance was the large gland volume. Conclusion: In patients with Graves’ disease, normoechogenic and large glands are associated with increased radioresistance.

Chest radiography in a 59-year-old woman with a respiratory tract infection revealed a large sharply demarcated intrathoracic mass occupying almost half of the right hemithorax with tracheal deviation to the left. Clinical examination revealed multinodular goiter with substernal extension, precluding examination of the lower pole of the right thyroid lobe. A prophylactic total thyroidectomy was performed through a right thoracotomy and cervicotomy. The histological findings were compatible with a multinodular goiter without malignancy.

The adverse effect of shock-wave lithotripsy (SWL) for renal stones on blood pressure is currently defined as its post-treatment increase. On the contrary, we hypothesize that even mild, unilateral renal obstruction initiates an increase in blood pressure. Then, in absence of treatment-induced injury, the stone removal should decrease the blood pressure. We derived the formula to assess the expected change in the mean arterial pressure following relief of renal obstruction without affecting the kidney functions. The predictions were well replicated in the cohort of patients with renal stone treated with parenchyma-saving open surgery, with 6.4 mmHg decrease at 3 months. On the contrary, in SWL cohort, instead of the expected 4.7 mmHg decrease, the blood pressure was unchanged. In conclusion, the absence of decrease in blood pressure is a very common adverse effect of SWL, leading to an epidemiologically significant increase in the risk of arterial vascular events.

Summary Background Radioiodine therapy is a frequent option in treatment of patients with hyperthyroidism. Despite efforts to plan the thyroid absorbed dose by accounting for the gland size and radioiodine kinetics, the success of radioiodine therapy remains largely unpredictable. The current methods plan the mean thyroid radiation absorbed dose, assuming that it applies to target tissue – the thyroid follicular cells. However, the unique thyroid follicular structure and iodine kinetics may violate this assumption. Upon oral administration and capture by thyroid, the vast majority of time radioiodine spends in organified form in follicular colloidal lumen: the greater the follicle the more radiation is wasted before reaching the target cells. Hypothesis The 131 I radiation absorbed dose to thyroid follicular cells is less than the average thyroid dose, the more the greater the follicles. Thyroid echogenicity can be used to assess the amount of colloid in thyroid tissue, which in turn can be used to assess the follicle size and adjust the planned absorbed dose to patient-specific thyroid micro-architecture. Evaluation Animal data on intrathyroidal iodine kinetics were considered in conjunction with model predictions that relate the size of thyroid follicles with 131 I irradiation of follicular cells. It turned out that the correction factors in the range 5–40% should be applied to oral activities of radioiodine calculated by the standard method. Next, several histology studies documented that normoechogenic thyroids have relatively large follicles, while hypoechogenic thyroids are mostly cellular, with almost empty, small follicles. All these concur with clinical data that Graves' disease patients with normoechogenic thyroids that received 200Gy in thyroid had comparable outcome to Graves' disease patients with hypoechogenic thyroid that received 100–120Gy in thyroid. Conclusion Thyroid echogenicity is a probable clue to a better patient-specific dosimetry in radioiodine therapy of hyperthyroidism; direct evidences and precise estimates of benefits over current practices would be provided by controlled clinical trials.

Preoperative scintigraphic visualization of metastases from well-differentiated thyroid microcarcinoma in patients with Graves disease is extremely rare, as is the scintigraphic visualization of poorly differentiated thyroid carcinoma as a warm nodule. We present a patient with Graves disease and both of these rare entities. A 47-year-old woman complained of a growing left-side neck mass and symptoms of thyrotoxicosis. On clinical examination, the thyroid was palpable without discernible nodularity, while the left side of the neck was occupied by 3 gross, painless nodules. She also had signs of thyrotoxicosis and biochemical parameters of Graves hyperthyroidism. Ultrasound examination showed moderately hypoechogenic thyroid with a small hypoechogenic nodule in the upper pole of the left lobe and 3 gross, almost normoechogenic nodules on the left side of the neck. On Tc-99m-pertechnetate pinhole scintigraphy there was a small, warm nodule in the upper pole of the left lobe and 3 gross metastatic nodules on the left side of the neck. Fine needle aspiration of the neck nodules was consistent with metastases from thyroid papillary carcinoma. After thyrostatic preparation a total thyroidectomy with left modified radical neck dissection was done. Histopathologic examination disclosed 2 carcinomas in the left thyroid lobe. One of them was a tall cell variant of papillary carcinoma in the upper pole of the left lobe that measured 5 mm and corresponded to the small warm nodule, and the second one was a classic form of papillary microcarcinoma that measured 2 mm. Metastases accrued from the classic form of papillary microcarcinoma. Although the patient had 2 thyroid carcinomas, one with metastases and the other of more aggressive form, which is consistent with advanced stage and aggressiveness, she is now disease-free, 4 years after the operation and radioiodine ablation.

We tested the hypotheses that chronic human urinary obstruction impairs the renal regulation of the red blood cell (RBC) production and compared the chronic outcome of relief of obstruction between parenchyma-saving surgery and extracorporeal lithotripsy (SWL). We measured RBC count and serum erythropoietin (Epo) concentration before and 3 months after relief of urinary obstruction in 60 patients treated with pyelolithotomy, ureterolithotomy or ureteroscopy and in 62 patients treated with SWL. Compared with 333 healthy controls, at baseline, patients scheduled for parenchyma-saving surgery had lowered RBC count [9.9% (6.9–13.1); 95% confidence interval] in case of males and 17.7% (14.2–21.4) in case of females; minor depression in RBC count was also observed in female patients scheduled for SWL. Epo serum levels were mildly reduced in SWL patients and halved in parenchyma-saving surgery group. At 3 months following relief of obstruction in 50 operated patients without recurrent or residual stone, Epo levels almost doubled, becoming normal, while RBC count and haemoglobin concentration increased for 6.1% (3.8–8.8) and 8.8% (6.1–10.6). In contrast, in 49 SWL patients only minor, bidirectional responses to treatment were observed. We conclude that obstructive uropathy is associated with clinically relevant effects on erythropoiesis, which is reversed after relief of obstruction by parenchyma-saving surgery that saves the renal parenchyma.

Studies of fracture healing are aimed at differentiating normal from delayed bone union. Delayed union, nonunion with the development of pseudarthrosis, and infection are complications of fracture healing. In the present study, quantitative analysis by three-phase bone scintigraphy was evaluated in the early prognosis of the course of fracture healing, to assess its potential in the early detection and therapy of healing complications. In 105 patients with long bone fractures, three-phase bone scintigraphy was performed early (day 4-7), and 3 weeks, 3 months and 6 months of injury. Based on clinical, laboratory and radiological findings, patients were retrospectively divided into four groups of normal healing, pseudarthrosis, delayed union, and healing with infection. The region of interest method was used to analyze all three scintigraphy phases, i.e. perfusion, vascular space image, and static scintigram at 3 h of injection. Comparison of impulse count in the fracture area with the contralateral, intact side produced a relative index for each step of three-phase scintigraphy. Infection at the fracture site can be suspected on the basis of perfusion index in the earliest stages following injury. Delayed bone union can also be predicted very early, within three weeks of injury, by use of perfusion index. Quantitative analysis of the vascular space phase and late static scintigrams can contribute to the diagnosis of complications, however, only in later stages of disease, which in part limits their clinical relevance. Three-phase bone scintigraphy is a valuable study when expecting problems in the process of bone union., Ispitivanje zarastanja prijeloma ima za cilj razlikovanje normalnog od usporenog zarastanja kosti. Odloženo zarastanje, nezarastanje s razvojem pseudoartroze te infekcija komplikacije su zarastanja prijeloma. S ciljem što ranijeg otkrivanja, a time i ranije terapije komplikacija, željeli smo ispitati mogućnosti kvantitativne analize troetapne scintigrafije kosti u ranoj prognozi tijeka zarastanja prijeloma. U 105 ispitanika s prijelomima dugih kostiju učinjena je troetapna scintigrafija kosti neposredno nakon traume (4.-7. dan nakon traume), te 3 tjedna, 3 i 6 mjeseci nakon traume. Ispitanici su na osnovi kliničkih, laboratorijskih i radioloških nalaza retrospektivno podijeljeni u četiri skupine: normalno zarastanje, pseudoartroza, odloženo zarastanje i zarastanje uz infekciju. Metodom regije interesa (ROI) analizirali smo sve tri faze scintigrama: perfuziju, snimku vaskularnih prostora, te statički scintigram 3 sata nakon injiciranja. Uspoređujući broj impulsa područja frakture s kontralateralnom, zdravom stranom dobili smo relativne indekse (RI) za svaku fazu troetapne scintigrafije. U najranijim stadijima nakon povrede moguće je, na temelju indeksa perfuzije, posumnjati na infekciju na mjestu frakture. Odloženo zarastanje također se može predskazati indeksom perfuzije vrlo rano, unutar tri tjedna od prijeloma. Kvantitativna analiza faze vaskularih prostora i kasnih statičkih scintigrama može doprinijeti dijagnostici komplikacija, ali u kasnim fazama bolesti, što donekle umanjuje njihovo kliničko značenje. Troetapna scintigrafija kosti vrijedna je pretraga u slučajevima kada se očekuju problemi zarastanja kosti.

To compare the effects of a selective beta-blocker atenolol and a nonselective beta-blocker propranolol on platelet aggregation.Twenty successive outpatients with moderate essential hypertension (6 women and 14 men, mean age-/+standard deviation 42.6-/+8.5 years) were randomized to either propranolol (40 mg three times a day) or atenolol (100 mg once a day) for the first two weeks, followed by a one-day washout period, and then a two-week administration of the alternative drug. Along with standard examinations and tests, circulating platelet aggregates were measured.There were no significant differences in creatinine, blood glucose, potassium, total cholesterol, hemoglobin, red blood cells (RBC), or platelets in three periods: baseline, atenolol, and propranolol period. Significant and comparable reductions in systolic and diastolic arterial pressure, body weight, heart rate, and HDL-cholesterol were recorded in both patient groups. The LDL-cholesterol concentration increased significantly in propranolol compared with both baseline and atenolol period. Serum triglycerides increased significantly with both medications. The number of circulating platelet aggregates decreased significantly with propranolol (0.99-/+0.19) in comparison with both atenolol (1.41-/+0.70; P=0.004, Wilcoxon matched pairs test) and baseline (1.59-/+0.94; P=0.002, Wilcoxon matched pairs test).Propranolol inhibits platelet aggregation more than atenolol and may have a favorable effect on the management of hypertension especially in patients with increased cardiovascular risk.

Retrotracheal goiters are rarely diagnosed at the cervical level (i.e., above the plane of the thoracic inlet).

We comment the article (J. Nucl. Med. 49 (2008) 151-157) and conclude that, beyond the radioiodine uptake and its effective half-life, both the size of metasases and its structure determine the 131I radiation dose target cells.

We argued that modeling the thyroid as composed of identical follicles, packed as inside the cubes that are aligned side to side is unrealistic since this leaves too much space between diagonal neighbors and in reality these spaces are occupied by relatively small follicles. This assumption leads to underestimation of self-absorption of 131I radiation in coloidal lumens of the thyroid follicles. We conclude that the degree of intrathyroidal inhomogeneity of 131I beta radiation dose may be larger than estimated by Hindie et al. due to close packing of follicles, which is especially important in cases of relatively large follicles.

We hypothesized that abnormalities in connective tissue, found in women with genital descensus, could impact their pulmonary function.Therefore we compared lung flows and volumes between women with (n = 100) and without (n = 100) descensus.Patients exhibited highly significant decrements in all expiratory flows, especially in the peak expiratory flow (-35%) and other flows at large lung volumes. The forced vital capacity and forced expired volume at 1 second, but not their ratio, were also decreased (-16% and -17%, respectively). These differences were exaggerated in postmenopausal subjects and in patients with third degree of descensus, but did not depend on the presence of stress incontinence. Lung flows and volumes did not change between follicular and luteal phase of the cycle, either in patients or in controls. The forced vital capacity decreased with increasing years past the menopauses in patients (65 +/- 10 ml per year), but not in controls.In women with genital descensus deteriorations in lung ventilatory function were observed in association with the presence and duration of postmenopauses.

The validity of voiding cystourethrography (VCUG) for detecting vesicoureteral reflux in children and assessing its extent was compared with that of direct radionuclide cystography (DRNC). Of 131 patients with recurrent urinary tract infection, all underwent DRNC and most also VCUG. Vesicoureteral reflux was found at DRNC in nine renal units (9 patients) in which VCUG was negative. In 17 renal units (15 patients) VCUG showed reflux to the ureter, but not to the renal pelvis, whereas DRNC revealed backflow from the bladder up to the renal pelvis. Reflux visualized at DRNC but not at VCUG was defined as grade Io. In all cases with reflux of grade I according to current classifications, DRNC showed reflux up to the renal pelvis. These observations make the distinction between grades I and II reflux in presently used classification less relevant and indicated the possible pathway of renal infection in patients with grade I vesicoureteral reflux and in so-called “elusive” reflux. We propose the addition of an extra grade (Io) of vesicoureteral reflux.