Ayse Aktas

Preoperative evaluation of hyperparathyroidism: the role of dual-phase parathyroid scintigraphy and ultrasound imaging

ObjectiveThe aim of this study was to evaluate the efficacy of dual-phase 99mTc-methoxyisobutylnitrile (MIBI) parathyroid scintigraphy (PS) and ultrasound (US) in primary (pHPT) and secondary (sHPT) hyperparathyroidism.MethodsA total of 69 patients (mean age 47 ± 16; age range 14–79 years), including 19 patients with sHPT were enrolled in this study. Preoperative serum intact parathyroid hormone (iPTH) levels, calcium (Ca), phosphate (P), alkaline phosphatase, and 24-h urinary-free Ca measurements were obtained. Concomitant thyroid pathology was also recorded.ResultsHistopathology revealed 30 solitary adenomas and 71 hyperplastic glands in 55 patients. The remaining patients’ histopathology revealed normal parathyroid, thyroid, or lymph nodes. The sensitivities of MIBI and US in pHPT were 70% and 60%, respectively. It was 60% for both procedures in sHPT. The overall sensitivity of combined US + MIBI in pHPT and sHPT was 81% and 71%, respectively. The overall specificity of MIBI and US was 87% and 91%; positive predictive value (PPV) was 94% and 92%, respectively. MIBI and US identified the parathyroid pathology in 92% and 85% of patients in the non-concomitant thyroid disease group, and in 53% and 47% of patients in the concomitant thyroid disease group, respectively. The weight of the gland between primary and secondary hyperparathyroidism did not reveal a significant difference (P = 0.4). Significant differences were found with respect to age, PTH, Ca, and P levels between the pHPT and sHPT (P < 0.001). Intact PTH levels showed significant differences between MIBI positive and negative patients (P = 0.013), and also US positive and negative patients (P = 0.012). A significant negative correlation was found between iPTH and Ca at sHPT (P < 0.001).ConclusionsThe concomitancy of thyroid disease greatly influences scintigraphic and ultrasonographic detection of parathyroid pathology in pHPT and sHPT. The combination of MIBI and US appears promising for localizing parathyroid pathology in patients with both primary and secondary hyperparathyroidism. The concordance rate is high together with a lower chance of missing concomitant thyroid pathology, which might alter the surgical approach.

Transplanted Kidney Function Evaluation

The best option for the treatment of end-stage renal disease is kidney transplantation. Prompt diagnosis and management of early posttransplantation complications is of utmost importance for graft survival. Biochemical markers, allograft biopsies, and imaging modalities are used for the timely recognition and management of graft dysfunction. Among several other factors, improvements in imaging modalities have been regarded as one of the factors contributing to increased short-term graft survival. Each imaging procedure has its own unique contribution to the evaluation of renal transplant dysfunction. In the era of multimodality imaging and emerging clinical considerations for the improvement of graft survival, evaluating an imaging modality in its own right may not be relevant and may fall short of expectation. Recognized as being mainly a functional imaging procedure, radionuclide imaging provides valuable information on renal function that cannot be obtained with other imaging modalities. For evaluating and establishing the current place, indications, and potential applications of radionuclide renal transplant imaging, a classification of renal allograft complications based on renal allograft dysfunction is essential. The major factor affecting long-term graft loss is chronic allograft nephropathy. Its association with early posttransplantation delayed graft function and repeated acute rejection episodes is well documented. Long-term graft survival rate have not improve significantly over the years. Imaging procedures are most commonly performed during the early period after transplantation. There seems to be a need for performing more frequent late posttransplantation imaging for the evaluation of acute allograft dysfunction, subclinical pathology, and chronic allograft changes; for understanding their contribution to patient management; and for identification of pathophysiological mechanisms leading to proteinuria and hypertension. With its unique advantage of relating perfusion to function, the potential for radionuclide imaging to replace late protocol biopsies needs to be investigated.

The effect of trimebutine maleate on gastric emptying in patients with non-ulcer dyspepsia

The study was designed to investigate the effect of trimebutine maleate, a drug used in both hyperkinetic and hypokinetic motility disorders, on gastric emptying in patients with non-ulcer dyspepsia having prolonged gastric emptying rates and to compare the parameters used for the determination of the lag period observed during the emptying of solid foods from the stomach. Gastric emptying was measured by the radionuclide technique. Twenty normal volunteers and 43 patients with non-ulcer dyspepsia participated in the study. Radionuclide imaging was performed by using a solid meal labeled with99mTc-tin colloid. Of the patients with non-ulcer dyspepsia, 20 had prolonged gastric emptying. They were given three weeks of oral treatment with trimebutine maleate and had their radionuclide gastric emptying study repeated. Treatment with trimebutine maleate resulted in reduction in duration of the lag period and less retention of food at 100 minutes (p < 0.0005). After treatment with trimebutine maleate, no significant difference has been observed in the mean symptom score of patients with prolonged gastric emptying. Among the parameters used for the determination of the lag period, lag period determined by a mathematical equation (TLAG) has been found to be longer than the lag period determined by visual inspection of the images (VLAG) and there was correlation between the two parameters when the lag time was short.

Renal Scintigraphy Findings in Allograft Recipients With Increased Resistance Index on Doppler Sonography

AIM The measurement of intrarenal resistance indices (RIs) by doppler ultrasound plays an important role in the evaluation of renal transplant recipients. Although an elevated RI was initially considered to be specific for rejection, later studies revealed this parameter as a nonspecific marker of transplant dysfunction. In this study, we analysed Tc-99m DTPA renal scintigraphy findings in patients with increased RI during the early posttransplantation period. METHODS This study included 22 patients with increased RI on doppler sonography during the first week after transplantation. Twenty-two recipients with uncomplicated early postoperative courses were used as a control group. An RI value >0.7 was considered pathologic. All patients underwent Tc-99m DTPA renal scintigraphy just after doppler sonography. In addition to visual interpretation of images, renogram curves were evaluated for patterns suggestive of acute tubular necrosis and acute rejection. Glomerular filtration rate (GFR) was calculated using computer software. Perfusion time-activity curves were assessed for the presence of peak and plateau patterns to calculate this ratio (P:PL). RESULTS The mean value for P:PL in patients with increased RI and in the control group were 1.37 +/- 0.33 and 1.53 +/- 0.47, respectively (P < .05). The mean value for GFR was significantly lower in the patient group compared with control subjects. Six patients had normal perfusion and function (27%). Perfusion pattern and renogram changes were suggestive of acute tubular necrosis in 5 patients and acute rejection in 6 patients. These diagnoses were confirmed later with serial scintigraphic changes or biopsy results. Three patients had an accumulation pattern on the renogram suggesting partial obstruction. CONCLUSION During the early posttransplantation period an increased RI on doppler sonography was seen in both normal functioning grafts and those with allograft dysfunction. Renal scintigraphy with perfusion and renogram patterns highly suggestive of specific allograft pathologies seemed to provide useful information to distinguish early postoperative renal allograft pathologies.

Evaluation of pediatric liver transplant recipients using quantitative hepatobiliary scintigraphy.

THE first successful liver transplantation was performed in 1963. Since then, advances in surgical technique, immunosuppressive therapy, and treatment of posttransplant complications have dramatically improved the prognosis for patients who undergo this procedure. Further, refinement of preoperative nutritional management and the advent of techniques for reduced-size transplants have made liver transplantation the preferred treatment for pediatric patients with end-stage liver disease. The postoperative period is a critical and uncertain time for pediatric liver transplant recipients because of the possibility of various complications that lead to liver dysfunction. Possible complications include infection, rejection, hepatocyte damage, cholestasis, vascular occlusion, and biliary obstruction. Another important issue is that there may be no accompanying clinical signs when a graft starts to fail. Biochemical testing lacks sensitivity, especially in the early postoperative period. Biopsy is currently considered the only definitive method for identifying liver transplant problems, but this is an invasive procedure. Quantitative, non invasive methods are needed to diagnose graft dysfunction in the early stage. Radionuclide imaging methods may meet these requirements. The aim of this study was to assess the clinical value of serial quantitative hepatobiliary scintigraphy for monitoring graft function in pediatric liver transplant recipients.

The influence of post-exercise cardiac changes on thallium-gated myocardial perfusion scintigraphy findings in normal subjects

Background and aimDuring recovery after exercise, the heart rate and blood pressure return to a resting state more rapidly than the end-systolic left ventricular dimensions and fractional shortening. The aim of this study was to assess how exercise-related cardiac changes affect the interpretation of myocardial perfusion images in normal subjects. Systolic cardiac parameters on gated stress and rest images were evaluated in healthy young and elderly subjects. MethodsTwenty-six healthy young and 20 healthy elderly subjects participated in the study. An injection of 111–130 MBq of thallium-201 (201Tl) was given at peak exercise. Rest images were acquired 2.5 h after stress acquisition, 15 min after a second injection of 18.5–37 MBq of 201Tl. Data were analysed using automatic-processing software for quantitative gated single photon emission computed tomography (SPECT) (QGS). The parameters derived from QGS were the end-systolic volume (ESV), end-diastolic volume (EDV), left ventricular ejection fraction (LVEF), end-systolic surface area (ESSA) and end-diastolic surface area (EDSA). The difference between wall thickening in the basal and apical segments (ΔWT) was also calculated. Perfusion images were visually assessed for differences in cardiac size, evidence of reversible hypoperfusion and hot spots. ResultsIn the young group, LVEF was approximately 6% higher at stress than at rest. EDV, ESV, ESSA and EDSA were all significantly lower, and ΔWT was significantly higher, at stress than at rest. In the elderly group, the mean LVEF at stress was slightly higher than the finding at rest (P<0.05). Visual evaluation of perfusion images revealed mild reversible stress hypoperfusion in the inferoseptal region in eight young male subjects. ConclusionsIn healthy young subjects, post-exercise cardiac changes affect systolic functions detected on gated thallium myocardial perfusion scintigraphy, resulting in a smaller heart size during stress. This finding, accompanied by a significant difference in apex to base counts during stress, may cause basal portions of the heart to appear ischaemic. The absence of these findings in the elderly suggests a decrease in contractility with age.

Percutaneous transluminal balloon angioplasty in stenosis of native hemodialysis arteriovenous fistulas: technical success and analysis of factors affecting postprocedural fistula patency.

PURPOSE We aimed to determine the predictors of technical success and patency after percutaneous transluminal angioplasty (PTA) of de novo dysfunctional hemodialysis arteriovenous fistulas (AVF). METHODS We performed a retrospective analysis of first time PTA in 228 patients (129 men, 99 women; mean age, 56.8±14.6 years). Anatomical (location, length, grade, and number of stenoses) and clinical variables (sex, age, prior AVF, diabetes mellitus, AVF age, side, and location) were reviewed. RESULTS A total of 330 stenoses were found in 228 patients. PTA was technically successful in 96.3% of the stenoses (n=319). Clinical success was achieved in 97.2% (n=321). Early dysfunction (within six months) was positively correlated with patient age (P < 0.001) and diabetes (P < 0.005). Older age (P < 0.001) and diabetes (P = 0.002) were associated with a lower primary patency rate. Patient age (P %lt; 0.001), presence of diabetes (P = 0.023), length of stenosis (P = 0.003), early recurrence (P = 0.003) and presence of residual stenosis (P = 0.014) were associated with a lower secondary patency rate. CONCLUSION Patency of dysfunctional hemodialysis fistulas can be maintained safely with continuous follow-up and repeated interventions without shortening the venous segment by surgical revision. Percutaneous approach to hemodialysis access stenosis is an alternative to the conventional surgical approach and PTA is an effective treatment method for dysfunctional AVF.

Usefulness of hepatobiliary scintigraphy for the evaluation of living related liver transplant recipients in the early postoperative period.

AIM The aim of this study was to investigate the usefulness of hepatobiliary scintigraphy for the evaluation of liver grafts in the early postoperative period in patients receiving liver transplants from living related donors. MATERIALS AND METHODS Fifty-six liver transplant recipients who received grafts from living related donors were included in the study. We examined the hepatobiliary scintigraphies of all patients, which were performed 7 to 10 days after the transplantation. The scintigraphic images were evaluated visually in terms of hepatic parenchymal function and biliary and vascular complications. RESULTS In 44/56 recipients, hepatobiliary scintigraphy was completely normal in the early postoperative period. However, in 6/56 cases, scintigraphy was interpreted to show parenchymal dysfunction. In these patients, histopathologic confirmation by biopsies revealed four cases of hepatocellular damage/cholestasis, one acute rejection, and one cholangitis. In 3/56 patients, hepatobiliary scintigraphy demonstrated a hypoactive area in the liver graft; however, the other areas showed normal function. When the abdominal computed tomography (CT) and CT angiography were evaluated, these hypoactive areas were discovered to be related to minor vascular problems. In 3/56 liver graft recipients whose grafts showed normal parenchymal function scintigraphically, images were interpreted to indicate bile leak because accumulation of tracer was seen at an abnormal physiological site. CONCLUSION Hepatobiliary scintigraphy, which is a noninvasive and objective method, is useful to assess grafts in the early postoperative period among patients who received liver transplants from living related donors.

FROM DONOR TO RECIPIENT: Doppler US, power US and scintigraphy of kidney perfusion before and after transplantation

Purpose: To follow kidneys from the donor to the recipient by assessing whether perfusion changes occur by using duplex Doppler US, power Doppler US and scintigraphy. Material and Methods: The prospective study included 12 donors and their corresponding 12 recipients. For each donor, both donor kidneys were evaluated by duplex Doppler US, power Doppler US and scintigraphy 1 day before surgery. The same procedure was carried out on the renal allografts at days 1, 3, 5 and months 1 and 3 post-transplantation. Power Doppler findings were classified according to a grading system of 1 to 4. Resistive indices (RIs) were determined based on interlobar and segmental arterial flow. Peak systolic velocity and RIs of the main renal artery were also measured. A perfusion parameter named the peak-to-plateau ratio was calculated. Statistical analysis was performed using the paired-samples t-test. Results: Intrarenal RI elevation and decreased renal artery peak systolic velocity was observed in normally functioning recipient kidneys. Conclusion: Duplex Doppler sonography demonstrated that transplanted kidneys had an increase in intrarenal vascular resistance at 1 month and a decrease in renal artery peak systolic velocity at 3 months post-transplantation. Scintigraphy and power Doppler US did not reveal any statistically significant perfusion change in normally functioning kidneys from donor to recipient.

The efficacy of low and high dose 99mTc-MIBI protocols for intraoperative identification of hyperplastic parathyroid glands in secondary hyperparathyroidism

OBJECTIVE The aim of this study was to compare the efficacy of low- and high-dose (99m)Tc-MIBI protocols for intraoperative identification of hyperplastic parathyroid glands via gamma probe in secondary hyperparathyroidism. MATERIAL AND METHODS This retrospective study was conducted using a prospective database of 59 patients who had undergone radioguided subtotal parathyroidectomy between 2004-2012. The patients were studied in 2 groups. Group 1 (n=31) received 37 MBq (99m)Tc-MIBI intravenously in the surgical room approximately 10 min before the beginning of the intervention and surgery was performed under gamma probe guidance. Group 2 (n=28) received 555 MBq (99m)Tc- MIBI intravenously 2h before surgery, which was also performed under gamma probe guidance. Intraoperative gamma probe findings, laboratory findings, and histopathological findings were evaluated together. RESULTS Using acceptance of the histopathological findings as gold standard, sensitivity and specificity of intraoperative gamma probe for identifying hyperplastic parathyroid glands was 98% and 100%, respectively, in both groups. CONCLUSIONS In the light of these findings, it is concluded that the low-dose (99m)Tc-MIBI protocol might be preferable for intraoperative identification of hyperplastic parathyroid glands in secondary hyperparathyroidism patients because it was observed to be as effective as the high-dose (99m)Tc-MIBI protocol. Furthermore, the low-dose protocol does not have the disadvantages that are associated with the high-dose protocol.