Should functional renal scans be obtained prior to upper abdominal IMRT for pancreatic cancer?

BACKGROUND: Upper abdominal irradiation for pancreatic cancer is administered in close proximity to the radiation-sensitive kidneys. There is difficulty in defining dose-volume parameters to predict late renal toxicity after partial kidney irradiation. Less than 10% of the general population is estimated to have asymmetrical kidney function; however, there are no studies that examine this in patients with pancreatic cancer. The primary purpose of this study was to determine the prevalence of asymmetrical kidney function in patients with pancreatic cancer. A secondary aim was to determine if asymmetrical kidney function was associated with abnormal laboratory values or kidney size on computed tomography scans. Finally, we aimed to develop recommendations for when a functional renal scan in patients with pancreatic cancer should be ordered. METHODS AND MATERIALS: We performed a retrospective review of patients with resectable, borderline resectable, and locally advanced pancreatic cancer who received abdominal radiation therapy and had preradiation functional renal scans between 2009 and 2015. Asymmetrical kidney function was defined as a difference between the 2 kidneys that was ≥60%/40% on a functional renal scan. Serum studies (blood urea nitrogen [BUN], creatinine [Cr], and glomerular filtration rate [GFR]) and abdominal computed tomography scans were routinely obtained before simulation. RESULTS: Of the 204 patients examined, 23 (11.2%) had asymmetrical kidney function that was identified on preradiation functional renal scans. Elevated Cr or BUN, a GFR <60, or a medical history that suggested abnormal renal function were not significantly associated with asymmetrical kidney function. Only 6 of 23 patients (26%) with asymmetrical kidney function had a notable difference in kidney size. CONCLUSIONS: In our series, approximately 11% of patients with pancreatic cancer have asymmetrical kidney function that was not identified by kidney size, serum BUN, Cr, GFR, or a significant medical history. These data suggest that in cases in which renal radiation doses exceed a V18 of 20% to 30% or there is concern about baseline renal function, a functional renal scan should be considered.

Nonlocalizing imaging studies for hyperparathyroidism: where to explore first?

BACKGROUND: For patients with primary hyperparathyroidism (pHPT), imaging studies are obtained to facilitate minimally invasive parathyroidectomy. If imaging studies are nonlocalizing, it is not known if exploration should begin on a particular side or gland location. STUDY DESIGN: A retrospective review of a prospective parathyroid database was performed. The cohort consists of pHPT patients who underwent initial parathyroidectomy between December 1999 and July 2010 and had all preoperative imaging studies reported as nonlocalizing (negative or indeterminate). RESULTS: Of 880 patients, 151 (17%) had nonlocalizing imaging studies. Reasons for starting exploration on a particular side were identified in 78 (52%) patients and included concomitant thyroid pathology (53%), suspicion on surgeon re-review of imaging (38%), or earlier thyroidectomy (9%). Exploration began on the right in 52%, the left in 42%, and was unknown in 6%. The surgeon had suspicion on imaging in 30 patients and correctly started on the side of pathology in 19 (63%). Hyperfunctioning glands were in eutopic locations in 144 patients (95%) and 3 had intrathyroidal glands. In 111 patients (74%) with single gland disease, median adenoma weight was 320 mg (range 80 to 8,210 mg). There was no difference in adenoma laterality (p = 0.7) or location (p = 0.8). Intraoperative parathyroid hormone criteria were met in 145 (96%) patients and 149 are eucalcemic at last follow-up; 2 (0.7%) patients have persistent disease. CONCLUSIONS: In pHPT patients with nonlocalizing imaging, hyperfunctioning glands are not more frequently located on a particular side or anatomic position. Eutopic location is common and intraoperative parathyroid hormone monitoring should be used to guide the extent of surgery.

Pulmonary embolism in pregnancy: CT pulmonary angiography versus perfusion scanning.

OBJECTIVE: The purpose of this study was to evaluate the equivalence of CT pulmonary angiography and perfusion scanning in terms of diagnostic quality and negative predictive value in the imaging of pulmonary embolism (PE) in pregnancy. MATERIALS AND METHODS: Between 2000 and 2007 at a university hospital and a large private hospital, 199 pregnant patients underwent 106 CT pulmonary angiographic examinations and 99 perfusion scans. Image quality was evaluated, and the findings were reread by radiologists and compared with the original clinical readings. Three-month follow-up findings of PE and deep venous thrombosis were recorded. RESULTS: PE was found in four of the 106 patients (3.7%) who underwent CT pulmonary angiography. The overall image quality was poor in 5.6% of cases, acceptable in 17.9%, and good in 76.4%. Fourteen CT and nine radiographic studies showed other clinically significant abnormalities. Six patients had indeterminate CT pulmonary angiographic findings, three had normal perfusion scans, and none underwent anticoagulation. All perfusion scan findings were normal. There was one incomplete study, and follow-up CT pulmonary angiography performed the same day showed PE. Two of 99 studies (2.02%) showed intermediate probability of the presence of PE; PE was not found at CT pulmonary angiography, but pneumonia was found. PE was found in one postpartum patient 9 weeks after she had undergone CT pulmonary angiography and ultrasound with normal findings. None of the patients died. CONCLUSION: CT pulmonary angiography and perfusion scanning have equivalent clinical negative predictive value (99% for CT pulmonary angiography; 100% for perfusion scanning) and image quality in the care of pregnant patients. Therefore, the choice of study should be based on other considerations, such as radiation concern, radiographic results, alternative diagnosis, and equipment availability. Reducing the amount of radiation to the maternal breast favors use of perfusion scanning when the radiographic findings are normal and there is no clinical suspicion of an alternative diagnosis.

Early uptake of 99mTc-C2A in the acute phase of myocardial infarction as a prognostic indicator for follow-up cardiac dysfunction.

OBJECTIVE: The C2A domain of Synaptotagmin I is a molecular probe for the specific imaging of cell death. Here we test the hypothesis that the uptake of 99mTc-C2A in the acute phase of an infarction is associated with cardiac dysfunction in follow-ups. METHODS: The left coronary artery was occluded in Sprague-Dawley rats for 0, 10, 20, and 30 min. 99mTc-C2A was injected intravenously at 2 h of reperfusion. Anterior planar images were acquired with one million counts on a gamma camera 3 h after injection. 99mTc-C2A uptake was calculated as the total counts in the left ventricle region minus blood pool signal. The in-vivo signal detected was correlated with wall motion score index at 1 and 3 weeks follow-ups measured by echocardiography. RESULTS: 99mTc-C2A uptake was higher with increased ischemic time (2244+/-852, 4054+/-1223, and 6178+/-1451 for 10, 20, and 30 min ischemia, analysis of variance P<0.001). A significant correlation was found between 99mTc-C2A uptake and wall motion score index at 1 week (R=0.800, P=0.0006) and 3 weeks (R=0.810, P=0.0008). CONCLUSION: In this ischemia/reperfusion model, 99mTc-C2A uptake in the acute phase was associated with functional abnormality at 1 and 3 weeks. This demonstrates the potential diagnostic and prognostic value of 99mTc-C2A as a novel imaging agent.

Multidetector computerized tomography urography as the primary imaging modality for detecting urinary tract neoplasms in patients with asymptomatic hematuria.

PURPOSE: We determined whether multidetector computerized tomography urography is sensitive and specific for detecting urinary tract neoplasms when used as the primary imaging modality for evaluating patients with hematuria. MATERIALS AND METHODS: A retrospective review was performed of the radiological, urological and pathological records of 468 patients without a history of urinary neoplasms who presented with hematuria. All patients underwent multidetector computerized tomography urography and complete urological evaluation, including cystoscopy. Laboratory urinalysis and cytology were done in 350 and 318 of the 468 patients, respectively. Multivariate logistic regression analysis was performed using the variables multidetector computerized tomography urography diagnosis, worst urine cytology, number of red blood cells per high power field, gross hematuria, age and gender to predict urinary tract neoplasm. RESULTS: A total of 50 urinary neoplasms were diagnosed in 468 patients. Multidetector computerized tomography urography detected 32 of 50 neoplasms for a sensitivity of 64%, specificity of 98%, positive predictive value of 76% and negative predictive value of 96%. There were 10 false-positive and 18 false-negative multidetector computerized tomography urography studies. Multivariate logistic regression showed that abnormal multidetector computerized tomography urography findings, ie neoplasm (p <0.0001), and suspicious or positive urine cytology (p = 0.0009) were significant. Patients with an abnormal multidetector computerized tomography urography diagnosis and suspicious or positive urine cytology had 44 and 47 times greater odds, respectively, of having urinary neoplasms compared to the odds in those with normal examinations. CONCLUSIONS: Multidetector computerized tomography urography is relatively sensitive and highly specific for detecting urinary neoplasms. It may serve as the primary imaging modality to evaluate patients with hematuria. Multidetector computerized tomography urography does not eliminate the role of cystoscopy in the evaluation of hematuria.

SPECT imaging of myocardial infarction using 99mTc-labeled C2A domain of synaptotagmin I in a porcine ischemia-reperfusion model.

INTRODUCTION: The C2A domain of synaptotagmin I recognizes necrotic and apoptotic cells by binding to exposed anionic phospholipids. The goal is to explore the potential imaging utility of 99mTc-labeled C2A in the detection of acute cardiac cell death in a porcine model that resembles human cardiovascular physiology. METHODS: Ischemia (20-25 min) was induced in pigs (M/F, 20-25 kg) using balloon angioplasty. 99mTc-C2A-GST (n=7) or 99mTc-BSA (n=2) was injected intravenously 1-2 h after reperfusion. Noninfarct animals were injected with 99mTc-C2A-GST (n=4). SPECT images were acquired at 3 and 6 h postinjection. Cardiac tissues were analyzed to confirm the presence of cell death. RESULTS: Focal uptake was detected in five out of seven subjects at 3 h and in all infarct subjects at 6 h postinjection but not in infarct animals injected with 99mTc-BSA or in noninfarct animals with 99mTc-C2A-GST. Gamma counting of infarct versus normal myocardium yielded a 10.2+/-5.7-fold elevation in absolute radioactivity, with histologically confirmed infarction. CONCLUSIONS: We present data on imaging myocardial cell death in the acute phase of infarction in pigs. C2A holds promise and warrants further development as an infarct-avid molecular probe.

99mTc-labeled C2A domain of synaptotagmin I as a target-specific molecular probe for noninvasive imaging of acute myocardial infarction.

UNLABELLED: The exposure of phosphatidylserine (PtdS) is a common molecular marker for both apoptosis and necrosis and enables the simultaneous detection of these distinct modes of cell death. Our aim was to develop a radiotracer based on the PtdS-binding activity of the C2A domain of synaptotagmin I and assess 99mTc-C2A-GST (GST is glutathione S-transferase) using a reperfused acute myocardial infarction (AMI) rat model. METHODS: The binding of C2A-GST toward apoptosis and necrosis was validated in vitro. After labeling with 99mTc via 2-iminothiolane thiolation, radiochemical purity and radiostability were tested. Pharmacokinetics and biodistribution were studied in healthy rats. The uptake of 99mTc-C2A-GST within the area at risk was quantified by direct gamma-counting, whereas nonspecific accumulation was estimated using inactivated 99mTc-C2A-GST. In vivo planar imaging of AMI in rats was performed on a gamma-camera using a parallel-hole collimator. Radioactivity uptake was investigated by region-of-interest analysis, and postmortem tetrazolium staining versus autoradiography. RESULTS: Fluorescently labeled and radiolabeled C2A-GST bound both apoptotic and necrotic cells. 99mTc-C2A-GST had a radiochemical purity of >98% and remained stable. After intravenous injection, the uptake in the liver and kidneys was significant. For 99mTc-C2A-GST, radioactivity uptake in the area at risk reached between 2.40 and 2.63 %ID/g (%ID/g is percentage injected dose per gram) within 30 min and remained plateaued for at least 3 h. In comparison, with the inactivated tracer the radioactivity reached 1.06 +/- 0.49 %ID/g at 30 min, followed by washout to 0.52 +/- 0.23 %ID/g. In 7 of 7 rats, the infarct was clearly identifiable as focal uptake in planar images. At 3 h after injection, the infarct-to-lung ratios were 2.48 +/- 0.27, 1.29 +/- 0.09, and 1.46 +/- 0.04 for acute-infarct rats with (99m)Tc-C2A-GST, sham-operated rats with (99m)Tc-C2A-GST, and acute-infarct rats with 99mTc-C2A-GST-NHS (NHS is N-hydroxy succinimide), respectively. The distribution of radioactivity was confirmed by autoradiography and histology. CONCLUSION: The C2A domain of synaptotagmin I labeled with fluorochromes or a radioisotope binds to both apoptotic and necrotic cells. Ex vivo and in vivo data indicate that, because of elevated vascular permeability, both specific binding and passive leakage contribute to the accumulation of the radiotracer in the area at risk. However, the latter component alone is insufficient to achieve detectable target-to-background ratios with in vivo planar imaging.

Opacification of the genitourinary collecting system during MDCT urography with enhanced CT digital radiography: nonsaline versus saline bolus.

OBJECTIVE: The purpose of this study was to determine whether a saline bolus during CT urography improves urinary collecting system opacification and whether the addition of enhanced CT digital radiography (CTDR) improves urinary collecting system visualization with or without a saline bolus. MATERIALS AND METHODS: One hundred eight CT urography and enhanced CTDR examinations were reviewed. Fifty-four patients were given a saline bolus during CT urography, and 54 patients underwent CT urography without a saline bolus. Urinary collecting system opacification was evaluated by group (saline vs nonsaline), imaging technique (CT urography alone vs CT urography plus enhanced CTDR), number of enhanced CTDR images, and site of nonopacified urinary segments. Using a multivariate logistic regression model, we determined significance of variables and odds of complete opacification. RESULTS: In the saline group, 248 nonopacified sites were identified on CT urography alone and 95 sites with CT urography plus enhanced CTDR. In the nonsaline group, 185 nonopacified sites were identified on CT urography alone and 59 sites with CT urography plus enhanced CTDR. Combining both groups, 433 nonopacified sites were identified with CT urography alone and 154 sites with CT urography plus enhanced CTDR. Multivariate logistic regression showed significance for group (p = 0.010), imaging method (p < 0.0001), number of enhanced CTDR images (p = 0.048), and site of segment opacification (p < 0.0001). The renal pelvis shows the greatest odds and the distal ureter the lowest odds for complete opacification by group or imaging method. CONCLUSION: The addition of a saline bolus offers no improvement, whereas the addition of enhanced CTDR offers significant improvement in collecting system opacification during CT urography.

Positron emission tomography for staging and assessment of tumor response of hepatic malignancies.

(18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is a useful functional imaging method that complements conventional anatomic imaging modalities for screening patients with colorectal hepatic metastases and hepatocellular cancer to determine their suitability for interventional procedures. FDG PET is more sensitive in detecting colorectal cancer than hepatocellular cancer (~90% versus ~50%). The likelihood of detecting hepatic malignancy with FDG PET rapidly diminishes for lesions smaller than 1 cm. The greatest value of FDG PET in these patients is in excluding extrahepatic disease that might lead to early recurrence after interventional therapy. Promising results have been reported with FDG PET that may show residual (local) or recurrent disease before conventional imaging methods in patients receiving interventional therapy. For patients with colorectal hepatic metastases, many investigators believe that patients with PET evidence of recurrent hepatic disease should receive additional treatment even when there is no confirmatory evidence present on other methodologies. For patients with hepatocellular cancer no conclusions regarding the value of FDG PET for assessment of response to interventional therapy can be reached as there is almost no published data.

Positron emission tomography-computed tomography imaging characteristics of an inferior vena cava tumor thrombus with magnetic resonance imaging correlation.

Thrombus of the renal vein or inferior vena cava is a known complication of renal cell carcinoma (RCC). Accurate discrimination between bland and malignant thrombus can have significant implications toward clinical management. Distinguishing between these 2 entities is not usually possible with enhanced computerized tomography (CT) or magnetic resonance imaging. This case reports the role of combined positron emission tomography-CT imaging in the accurate detection of recurrent RCC after partial nephrectomy and surgically proven tumor thrombus in the renal vein and inferior vena cava.

The impact of solid-phase gastric emptying studies in the management of children with dyspepsia.

Information on the utility of solid-phase gastric emptying studies (SPGES) in the evaluation of children with symptoms of upper gastrointestinal (GI) motor dysfunction is limited. This study was conducted to evaluate the impact of SPGES in the clinical management and outcome of children with upper GI symptoms suggestive of gastroparesis. The records of 45 children who underwent SPGES (31F; 3-17 years) were reviewed. All patients had GI symptoms suggesting gastroparesis. Patients were fed with Tc-99m-sulfur colloid-labeled chicken liver. Adult normal half-life (T1/2) values (F 103 +/- 14 minutes; M 66 +/- 13.6 minutes) were used. The relationships among symptoms, treatment, and outcome were evaluated. Of the 45 patients 9 had delayed, 16 had rapid, and 20 had normal gastric emptying. Six of 9 patients with delayed gastric emptying responded to cisapride. Four of 16 patients with rapid emptying were diagnosed with the dumping syndrome. Of the children with rapid gastric emptying, 87% were females. Twenty patients with normal emptying were diagnosed with gastroesophageal reflux (8), nonulcer dyspepsia (5), irritable bowel syndrome (2), Helicobacter pylori (1), lactose intolerance (1), eosinophilic gastroenteritis (1), duodenitis (1), and constipation (1). In patients who had SPGES for possible gastroparesis, 20% had gastroparesis, 36% had rapid gastric emptying, and 44% had normal gastric emptying. The high number of females in the rapid gastric emptying group might be secondary to normal adult female T1/2 values that were used. The practice of using adult normal T1/2 values in prepubertal girls may need to be revised. Patients with delayed gastric emptying responded to cisapride.

Preparation of 99mTc labeled substance P (SP).

Substance P (SP) is an ll-amino acid neuropeptide of the tachykinin family. This study investigated the preparation of an SP analog labeled with 99mTc for imaging SP receptor positive tissue (inflammatory diseases and neoplasms with increased expression of SP receptors). High specific activity 99mTc-SP was prepared using the l-imino-4-mercaptobutyl (IMB) group as a bifunctional chelator. Biological distribution in mice showed increased 99mTc-SP uptake in the salivary glands (which have a high concentration of SP receptors), but this activity was displaced in animals pre-treated with excess non-radioactive SP. These data show that the uptake of 99mTc-SP is receptor specific. IMB derivatization at the N-terminal location is suitable for labeling of SP analogues with 99mTc. Synthetic analogues of SP labeled with 99mTc may be an attractive alternative to 111In labeled molecules and merit further investigation.