Comparison of Ga-68 PSMA positron emission tomography/computerized tomography with Tc-99m MDP bone scan in prostate cancer patients

Background/aim: The aim of our study was to compare Tc-99m MDP bone scan and Ga-68 PSMA PET/CT in terms of detection of bone metastasis in prostate cancer patients. Materials and methods: A total of 28 prostate cancer patients with bone scan and PSMA PET/CT performed within 90 days were retrospectively included in our analysis. All bone lesions were scored as negative (score-0), positive (score-1), or suspicious (score-2) for metastasis by two experienced nuclear medicine physicians. Both patient-based and region-based analyses were made for all osseous lesions. Results: On per-patient analysis; sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were 72.7%, 52.9%, 50%, 75%, and 60.7%, respectively, for bone scan and 90.9%, 100%, 100%, 94.4%, and 96.4%, respectively, for PSMA PET/CT. On per-region analysis; sensitivity, specificity, PPV, NPV, and accuracy were 76.2%, 80.9%, 57.1%, 91.1%, and 79.8%, respectively, for bone scan and 85.7%, 100%, 100%, 95.5%, and 95.4%, respectively, for PSMA PET/CT. Conclusion: Ga-68 PSMA PET/CT has higher sensitivity, specificity, and accuracy compared to bone scan in terms of bone metastasis detection in prostate cancer patients. Therefore, it might be the modality of choice for patients with suspicion for metastatic disease, despite negative bone scan and conventional imaging results

Utility of left lateral supine position for myocardial perfusion single-photon emission computed tomography compared with other methods of correcting inferior wall attenuation.

INTRODUCTION: Single-photon emission computed tomography (SPECT) myocardial perfusion imaging is an accepted method for reflecting the pathophysiological significance of lesions detected by coronary angiography. However, it has an inherent drawback in terms of false-positive perfusion defects for the inferior myocardial wall. To overcome this problem, different acquisition techniques have been proposed, including the computed tomographic-based attenuation correction method. In this respect, a new imaging technique, left supine lateral position SPECT myocardial perfusion imaging with technetium-99m methoxyisobutylisonitrile (Tc-99m MIBI), has been proposed to eliminate this problem and its value has been investigated in this report. MATERIALS AND METHODS: Sixty-two patients were prospectively and randomly enrolled in this study. They underwent Tc-99m MIBI SPECT in the supine, prone, left lateral, and sitting positions after an adequate stress test on the same day.The presence and extent of defects on stress images were noted in the supine image data set for the 11 myocardial segments, which were then labeled as 1 or 0 if a defect was present or absent, respectively. This evaluation sequence was repeated in all other image data sets. When defects persisted in other scan positions it was regarded as true positive, and when they were resolved they were regarded as false positive. By this means, the percentages of resolving perfusion defects by that imaging position were calculated for each observer per positional pair under comparison. RESULTS: From six interpretations carried out by the nuclear medicine physicians, 6×11×3=198 four-fold tables in 11 segments were analyzed for discrepancies between position pairs. In 31 of 33 discrepant interpretations, defects observed in any of the other positions were resolved in the lateral position. Only in two evaluations of one observer were the discrepancies against lateral positioning for the anterior wall. If the inferior wall was considered alone, it was clearly obvious that lateral positioning was more accurate than the other positions.Intraobserver evaluation showed the methodology to be highly reproducible.The SPECT findings were concordant with coronary angiography results in selected patients. CONCLUSION: Visual and quantitative evaluations of the variation in inferior wall activity lead us to suggest that SPECT imaging with Tc-99m MIBI be performed in the left lateral position to allow better visualization of the inferior and septal walls in those departments not able to utilize computed tomographic attenuation correction.

Comparison of 68Ga-DOTATATE and 68Ga-DOTANOC PET/CT imaging in the same patient group with neuroendocrine tumours.

PURPOSE: Recent studies have suggested that positron emission tomography (PET) imaging with (68)Ga-labelled DOTA-somatostatin analogues (SST) like octreotide and octreotate is useful in diagnosing neuroendocrine tumours (NETs) and has superior value over both CT and planar and single photon emission computed tomography (SPECT) somatostatin receptor scintigraphy (SRS). The aim of the present study was to evaluate the role of (68)Ga-DOTA-1-NaI(3)-octreotide ((68)Ga-DOTANOC) in patients with SST receptor-expressing tumours and to compare the results of (68)Ga-DOTA-D-Phe(1)-Tyr(3)-octreotate ((68)Ga-DOTATATE) in the same patient population. METHODS: Twenty SRS were included in the study. Patients' age (n = 20) ranged from 25 to 75 years (mean 55.4 ± 12.7 years). There were eight patients with well-differentiated neuroendocrine tumour (WDNET) grade1, eight patients with WDNET grade 2, one patient with poorly differentiated neuroendocrine carcinoma (PDNEC) grade 3 and one patient with mixed adenoneuroendocrine tumour (MANEC). All patients had two consecutive PET studies with (68)Ga-DOTATATE and (68)Ga-DOTANOC. All images were evaluated visually and maximum standardized uptake values (SUV(max)) were also calculated for quantitative evaluation. RESULTS: On visual evaluation both tracers produced equally excellent image quality and similar body distribution. The physiological uptake sites of pituitary and salivary glands showed higher uptake in (68)Ga-DOTATATE images. Liver and spleen uptake values were evaluated as equal. Both (68)Ga-DOTATATE and (68)Ga-DOTANOC were negative in 6 (30 %) patients and positive in 14 (70 %) patients. In (68)Ga-DOTANOC images only 116 of 130 (89 %) lesions could be defined and 14 lesions were missed because of lack of any uptake. SUV(max) values of lesions were significantly higher on (68)Ga-DOTATATE images. CONCLUSION: Our study demonstrated that the images obtained by (68)Ga-DOTATATE and (68)Ga-DOTANOC have comparable diagnostic accuracy. However, (68)Ga-DOTATATE seems to have a higher lesion uptake and may have a potential advantage.

Cardiac hydatid cyst mimicking malignancy.

A 50-year-old man presented with chest pain symptoms for 7 years. He did not report any other complaints. The diagnostic tests including physical examination, routine laboratory tests, chest x-ray, and electrocardiography were reported as normal. Cardiac MRI, however, revealed a 64 × 66 mm mass lesion in the left myocardium. He was referred to our unit for further tests. A PET/CT was carried out which demonstrated a minimally increased fluorodeoxyglucose uptake at the peripheral margins of the mass, which deemed to be suspicious for malignancy. The patient underwent a thoracotomy and the cardiac mass was excised. Histopathologic examination reported this lesion as a hydatid cyst.

Significance of increased scrotal Tc-99m MDP uptake in patients with prostate cancer.

OBJECTIVE: We observed an unusually increased scrotal uptake as an interesting finding in some patients with prostate cancer who were scanned for any possible metastatic disease. This study was designed to investigate the significance of this incidental finding in the technetium-99m methylene diphosphonate scintigraphies. METHODS: The study population consisted of 104 patients with biopsy-proven prostate cancer (group I), 55 male patients with other cancers (group II), 30 male patients with nonmalignant diseases (group III) and finally 15 patients with benign prostate hypertrophy (group IV). The square-shaped regions of interest are placed centrally on the scrotum and then on the lateral femoral soft tissue. Then the simple ratios of the scrotal and femoral soft tissue mean counts (S/Bg) were calculated. The statistical significance of differences among the groups in terms of scrotal uptake was determined. RESULTS: Group I showed increased scrotal uptake relative to the other groups. The mean uptake ratios (S/Bg±standard deviation) were 3.49±1.42 in group I, 2.89±0.70 in group II, 2.87±0.75 in group III, and 2.91±0.60 in group IV. This ratio was significantly higher in patients with prostate cancer than the normal group (P=0.024), the group with benign prostate hypertrophy (P=0.004), and the patients with other cancers (P=0.004). CONCLUSION: Our results showed that technetium-99m methylene diphosphonate bone scintigraphy, as a routine for detecting metastatic disease or performed for other purposes, could give clues for a hidden prostate cancer. Then, in elderly male patients, we strongly recommend that it is wise to keep one's eye on scrotal activity when bone scans are read and where there is any doubt, take appropriate regions of interest to make quantitative evaluations.

Radiation protection for accompanying person and radiation workers in PET/CT.

The purposes of the present study are to measure the total radiation doses for the radiation workers and for the accompanying person to the patients in positron emission tomography (PET)/computed tomography (CT) imaging. Urines samples from the patients were collected at 43, 62, 87, 117, 238, 362 min after the 555-MBq (18)flour-fluorodeoxyglucose ((18)F-FDG) injection and activities were measured. Dose rates were recorded using a Geiger-Muller counter and the total radiation doses were measured with using an electronic personnel dosemeter. According to the results here, 18.4 % of (18)F-FDG was excreted in the urine in 117 min after injection. At 117th min after injection, dose rates were determined as 345, 220, 140, 50 and 15 µSv h(-1), at proposed distances. The radiation doses after 117 min were measured as 3.92 mSv at 0.1 m, 2.11 mSv at 0.25 m and 1.08 mSv at 0.5 m. In conclusion, radiation protection will be sufficient within 2 h after (18)F-FDG injection for PET/CT imaging in daily practice.

Coronary artery calcification and coronary ischaemia in renal transplant recipients.

BACKGROUND: Cardiovascular disease is the leading cause of mortality among renal transplant recipients. Data on the relationship between coronary artery calcification (CAC) and coronary ischaemia in renal transplantation patients are scant. We conducted a study to determine the prevalence and determinants of CAC in these patients; we also examined the frequency of coronary ischaemia in patients with moderate and severe CAC. METHODS: We used multi-detector spiral computed tomography to examine CAC in 178 consecutive renal transplant recipients. Angina pectoris was sought with the Rose questionnaire. The extent of calcification was measured by Agatston score. Myocardial perfusion scintigraphy was performed in patients with moderate and severe CAC. Multivariate logistic and linear regression analysis was used to evaluate the determinants of CAC presence and CAC score, respectively. RESULTS: CAC was present in 72 patients (40.4%), mean CAC score was 113.7±275.5 (median: 0 and range: 0-1712). Age, time on transplantation and Rose angina pectoris were the independent determinants of both CAC presence and high CAC scores in all multivariate models. Coronary ischaemia was detected in 17.1% of the patients with moderate-to-severe CAC. CONCLUSIONS: CAC is highly prevalent in renal transplant recipients; it is associated with symptoms of coronary ischaemia. Time on transplantation is an independent determinant of CAC. Future studies to evaluate the prognostic significance of CAC in these patients are necessary.

The Diagnostic Role of FDG PET/CT in Patients with Fever of Unknown Origin.

OBJECTIVE: Fever of unknown origin (FUO) is a challenge for the physician and needs use of clinical, laboratory, and imaging studies and also invasive and/or non-invasive interventions to detect the etiology. The aim of present study was to assess the role of FDG PET/CT in determining the etiology in patients with FUO. MATERIAL AND METHODS: Twenty-four patients (median age 52, range 5-77 years, 6 female, 18 male) who were diagnosed with FUO were retrospectively analyzed in this study. Before the FDG PET/CT studies, none of them had a definitive reason for their diseases investigated by conventional radiological or scintigraphic methods, clinical and laboratory observations. RESULTS: The positive result was achieved in 19 (79.2%) of 24 patients as findings of the FDG PET/CT. However, FDG PET/CT was useful for definitive diagnosis in 12 (63.2%) of 19 positive patients. Malignant diseases were determined to be the underlying cause of FUO in 5 (41.6%) of 12 patients. Noninfectious inflammatory causes were detected in 2 (16.7%) patients, infections were exhibited in 3 (25%) patients, and miscellaneous diseases demonstrated in 2 (16.7%) patients. In 7 patients the detected pathological uptakes on FDG PET/CT were not helpful for the definitive diagnosis. In remaining 5 patients who showed no pathological uptake in the FDG PET/CT, diagnosis could not be established by other methods, as well. The sensitivity, specificity, and positive and negative predictive values for the determination of FUO etiology were 92.3%, 45.4%, 63.1%, and 100% for FDG PET/CT. CONCLUSION: Our results demonstrate that FDG PET/CT seems to have considerable contribution to reveal the reason of undiagnosed patients with FUO investigated by conventional diagnostic methods, clinical and laboratory observations. CONFLICT OF INTEREST: None declared.

Temporal relationship between gastroesophageal reflux and rate of gastric emptying in children.

OBJECTIVES: There are conflicting reports for the relationship of reflux and the gastric emptying rate. In addition, the acquisition period is not well defined for the gastroesophageal reflux studies. The aim of our study was to evaluate the temporal distribution of the reflux episodes and to evaluate whether the gastric emptying rate changed with the gastroesophageal reflux time or amount. METHODS: We used radionuclide scintigraphy to evaluate 211 pediatric patients (0-10 years of age). Scintigraphic studies were performed by acquiring 15 s images for 1 h in a supine position after ingesting milk containing 0.5 mCi (18.5 MBq) Tc-99m colloid. Reflux episodes were calculated every 10 min for each patient who had reflux. The gastric emptying rate was measured by drawing an region of interest over the gastric activity. RESULTS: Gastric reflux was observed in 104 patients (49.28%). The number of reflux episodes was higher in the first and second 10 min (33.7 and 29.1% respectively). The lowest reflux episode was observed in the last 10 min (between 50 and 60 min) (2.6%) suggesting that the reflux episode was decreasing by the gastric emptying. Within the first 30 min, reflux was observed in 98 of 104 patients (94.23%). The gastric emptying rate was calculated to be 73 min in patients with a higher incidence of reflux and 62 min in patients who had delayed and lower incidence of reflux episodes. In 104 patients, the average gastric emptying rate was 71.60 min. There were no significant differences in the gastric emptying rates between patients who had reflux episodes beginning in the first 30 min of the study and those who had reflux episodes in the last 30 min of the study (P>0.05). CONCLUSION: This study has suggested that the number of reflux episodes were not related with the gastric emptying rate. However, reflux could be observed in a higher frequency before gastric emptying, which also suggested that a 30-min period may be sufficient when reflux is shown early. In negative cases, a 60-min acquisition time is recommended for the diagnosis of gastroesophageal reflux.

The value of different washout parameters in the evaluation of renal transplants by technetium-99m-ethylene- l-l-dicysteine.

Technetium-99m-ethylene-l-l-dicysteine ((99m)Tc-EC) is an agent with a potential for renal imaging. It is reported that EC uses the same tubular transporter system as ortho-hippurate (OIH) and mercaptoacetyltriglycine (MAG3) and that this agent has good imaging properties and higher renal clearance than MAG3. In this study we used (99m)Tc-EC to compare different washout parameters in renal transplanted patients. Sixty nine scans in 55 patients (38 males, 17 females) were performed with (99m)Tc-EC during the follow-up period after kidney transplantation. After bolus injection of 280MBq (99m)Tc-EC, 60x1sec and 29x1min images were taken in anterior position. Perfusions of transplanted kidneys were examined visually and perfusion indices (PI) were calculated according to Hilson's method. The semiquantitative washout parameters such as 20 and 30min to peak activity ratios and 20 and 30min to 3min activity ratios were calculated. The patients were clinically evaluated by nephrologists experienced in renal transplantation cases and followed-up by serum creatinine and blood urea nitrogen determinants which were checked every postoperative day until stabilized to a optimal level for each patient. Two standard deviations above the mean values derived from all cases with normal functioning transplanted kidneys were calculated for each method. Then, these values served as the threshold to differentiate the pathological cases respectively. Of the 69 total studies performed, we found 34 normal kidneys, 14 rejections, 19 acute tubular necrosis (ATN) and 2 cyclosporin A toxicity cases. The number of abnormal cases detected with 30/3min, 30/max, 20/3min and 20/max indices were 27, 26, 24, and 18, respectively. In conclusion, we strongly recommend in studying renal transplants to consider the activity at the 3(rd) min post injection as a reference point instead of the time to maximum activity for washout index calculation. If, for any reason the time to maximum counts using (99m)Tc-(peak activity) is prefered, then the period of study should not be performed for less than 30min to achieve reliable results.

Intravascular radiation therapy with a Re-188 liquid-filled balloon in patients with in-stent restenosis.

OBJECTIVE: The aim of this study was to evaluate the feasibility and safety of intravascular radiation therapy (IVRT) using Re-188 filled balloon system in patients with in-stent stenosis. METHODS: A total of 39 patients with in-stent restenosis were enrolled as the IVRT (22 patients) and control groups (17 patients) of this study after a successful coronary angioplasty. For irradiation the angioplasty balloon was replaced by a noncompliant balloon of the same diameter but 10 mm longer in length with a proximal and distal radio-opaque marker to deliver the dose of 18 Gy at 0.5 mm depth from the surface of the balloon into the vessel wall. Angiographic follow-up was performed after 6 months. RESULTS: The length of the irradiated segment was between 9.14 and 22 mm and the diameter between 2.5 and 3 mm. In the IVRT group, two patients who did not receive antiplatelet therapy had myocardial infarction. Four patients who presented with stable angina earlier also had angiographically documented in-stent occlusion (two patients) and edge stenosis (two patients) of the target lesion and received angioplasty (18.1%). In the control group, three patients with recurrent angina and four asymptomatic patients had documented in-stent occlusion angiographically at 6 months and these seven patients underwent target lesion revascularization (41.2%). The overall restenosis rate in the IVRT and control groups were 23.91 and 39.86%, respectively (P=0.013). No complications were documented, except anginal pain and ST segment changes. CONCLUSION: Our results indicated that the Re-188 liquid-filled balloon is feasible, safe, and effective in patients with in-stent restenosis.

Ectopic parathyroid adenoma localized with MIBI scintigraphy and excised with guide of macroaggregated human serum albumin injection.

Primary hyperparathyroidism is caused by an excessive amount of parathyroid hormone secreted by one or more enlarged parathyroid glands. Most commonly primary hyperparathyroidism is caused by a parathyroid adenoma. Ectopic parathyroid adenomas are rare, but they can complicate the surgical treatment and have an increased morbidity and poorer success rate. Thus, preoperative imaging is particularly valuable in this group of patients with hyperparathyroidism. Preoperative imaging has opened up a new era of minimally invasive parathyroid surgery procedures. The radioguided occult lesion localization technique has become the preferred approach to preoperative localization of nonpalpable breast lesions in several breast units. In this report, we investigated the usefulness of the radio-guided occult lesion localization technique in the identification of ectopic parathyroid adenomas. We describe the case of a 66-year-old woman who was diagnosed to be hypercalcemic. Tc-99m methoxy-isobutyl-isonitrile scintigraphy identified an ectopic parathyroid adenoma. The patient's cervical region was scanned with the probe to localize an area of maximal radiotracer uptake and the hot area was identified by a gamma probe. Careful dissection was then carried out and an enlarged ectopic parathyroid gland was removed. In conclusion, the preoperative imaging of an ectopic parathyroid adenoma and the excision of this tissue with radioguided occult lesion localization technique can open up a new era of minimally invasive parathyroid surgery.

A doughnut sign of a hydatid cyst of the liver on F-18 FDG PET/CT.

A 59-year-old man underwent a whole-body PET/CT scan to evaluate the metabolic activity of a nodule in the upper lobe of the left lung seen on CT. Slightly increased peripheral activity with a large hypometabolic region centrally, a so-called doughnut sign, was seen in the right lobe of the liver. After the diagnosis of a hydatid cyst of the liver, the patient underwent surgery. This case demonstrates a hydatid cyst that caused increased F-18 FDG uptake as a doughnut pattern.

FDG PET/CT findings in recurrent malignant schwannoma.

Malignant schwannoma is an uncommon but aggressive sarcoma that most commonly arises in young and middle-aged adults. We present a 28-year-old male patient with a recurrent chest wall malignant schwannoma. An FDG PET/CT was performed to evaluate the management of the patient. The PET/CT images showed hypermetabolic mass lesions in the left upper chest wall and increased FDG uptake in the left axillary region. The pathologic results confirmed the PET findings. We conclude that FDG PET/CT could play an important role in the staging, restaging, and post-therapy follow-up of malignant schwannomas.

Is early bladder activity in radionuclide cisternography an indirect sign of spontaneous intracranial hypotension or sequence of lumbar puncture?

Spontaneous intracranial hypotension (SIH) is characterized by severe postural headache and low cerebrospinal fluid (CSF) pressure. Radionuclide cisternography (RC) is of some value in diagnosing CSF leakage causing SIH. However, the sensitivity of RC is too low to demonstrate the site of leakage. In these cases, the early appearance of the radioactivity in the urinary bladder has also been used as an indirect finding in the diagnosis of SIH. The aim of this study was to evaluate the diagnostic reliability of early urinary bladder activity as an indirect sign of SIH. We investigated early bladder activity in 21 patients with suspicion of normal pressure hydrocephalus. Of the 21 subjects, 13 (62%) showed early bladder activity. We demonstrated that early bladder activity is observed in patients without CSF leakage such as normal pressure hydrocephalus. Therefore, this indirect finding of RC is not a reliable finding in diagnosing SIH.

Female breast surface radiation exposure during FDG PET/CT examinations.

BACKGROUND: The combined positron emission tomography (PET) and computed tomography (CT) scanners have been developed in which CT data can be used for both anatomical landmarks and attenuation correction of PET images. However, this modality potentially introduces more radiation burden to patients compared to conventional PET scanning as a result of the added radiation exposure received from CT examination. The purpose of our study was to determine the breast radiation doses of combined PET/CT examination. MATERIAL AND METHODS: Patients' superficial breast doses were calculated using thermoluminescence dosimeters (TLDs) placed onto the surface of the breasts. TLDs were positioned before FDG injection and removed after 24 h. We also determined the average superficial and glandular breast radiation doses from the anthropomorphic dosimetric phantom imaged using similar CT protocol (low dose) to the patients' study. RESULTS: The mean superficial breast dose of the breast skin measured from the PET/CT studies was 14.42+/-2.41 mGy. The average superficial and glandular breast doses of the anthropomorphic phantom measured from the low-dose CT was 9.50 mGy and 5.94 mGy, respectively. CONCLUSION: This study showed that radiation exposure to the breasts during PET/CT was higher than the recommended doses. Therefore, combined PET/CT scanning must be used for essential indications, particularly in women of reproductive age and preferentially a low-dose CT protocol should be implemented to avoid overexposure in such patients.

Avoidance of misinterpretation of an FDG positive sacral insufficiency fracture using PET/CT scans in a patient with endometrial cancer: a case report.

Whole-body FDG PET is an important tool for imaging of cancer, including skeletal metastases. However, false-positive results can occur in benign diseases such as insufficiency fractures. We report a case of sacral insufficiency fracture in which increased FDG uptake was detected. Correlative CT images obtained by a combined PET/CT scanner excluded a possible false-positive interpretation by revealing the fracture lines at the site of increased FDG uptake.