Assessment of renal impairment by non-contrast-enhanced conventional magnetic resonance imaging: comparison with <Superscript>99m</Superscript>Tc-DTPA renography

Purpose  

The aim of this study was to determine whether non-contrast-enhanced magnetic resonance imaging (MRI) can detect three levels of renal impairment by evaluating the differences and agreement with ^99mTc-diethylenetriamine pentaacetic acid (DTPA) renography.     

Use of quantitative SPECT/CT reconstruction in <Superscript>99m</Superscript>Tc-sestamibi imaging of patients with renal masses

Objective

Technetium-99m (^99mTc)-sestamibi single-photon emission computed tomography/computed tomography (SPECT/CT) has previously been shown to allow for the accurate differentiation of benign renal oncocytomas and hybrid oncocytic/chromophobe tumors (HOCTs) apart from other malignant renal tumor histologies, with oncocytomas/HOCTs showing high uptake and renal cell carcinoma (RCC) showing low uptake based on uptake ratios from non-quantitative single-photon emission computed tomography (SPECT) reconstructions. However, in this study, several tumors fell close to the uptake ratio cutoff, likely due to limitations in conventional SPECT/CT reconstruction methods. We hypothesized that application of quantitative SPECT/CT (QSPECT) reconstruction methods developed by our group would provide more robust separation of hot and cold lesions, serving as an imaging framework on which quantitative biomarkers can be validated for evaluation of renal masses with ^99mTc-sestamibi.

Methods

Single-photon emission computed tomography data were reconstructed using the clinical Flash 3D reconstruction and QSPECT methods. Two blinded readers then characterized each tumor as hot or cold. Semi-quantitative uptake ratios were calculated by dividing lesion activity by background renal activity for both Flash 3D and QSPECT reconstructions.

Results

The difference between median (mean) hot and cold tumor uptake ratios measured 0.655 (0.73) with the QSPECT method and 0.624 (0.67) with the conventional method, resulting in increased separation between hot and cold tumors. Sub-analysis of 7 lesions near the separation point showed a higher absolute difference (0.16) between QPSECT and Flash 3D mean uptake ratios compared to the remaining lesions.

Conclusions

Our finding of improved separation between uptake ratios of hot and cold lesions using QSPECT reconstruction lays the foundation for additional quantitative SPECT techniques such as SPECT-UV in the setting of renal ^99mTc-sestamibi and other SPECT/CT exams. With robust quantitative image reconstruction and biomarker analysis, there may be an expanded role for SPECT/CT imaging in renal masses and other pathologic conditions.

     

A novel utility of <Superscript>99m</Superscript>Tc-GSA SPECT/CT fusion imaging: detection of inadequate portal vein embolization

Purpose

Our aim was to determine the utility of Tc-99m-diethylenetriaminepentaacetic acid-galactosyl human serum albumin single-photon-emission computed tomography (^99mTc-GSA SPECT/CT) fusion imaging for detecting incomplete portal vein embolization (PVE).

Materials and methods

Fifty-five candidates underwent PVE. Among them, five underwent second PVE. Detectability of first inadequate PVE using CT and ^99mTc-GSA SPECT/CT fusion imaging was analyzed.

Results

Cases of inadequate PVE were detected in three patients using CT and in five using ^99mTc-GSA SPECT/CT fusion imaging. Fusion imaging detected two cases of insufficient PVE in which portal branches were apparently well embolized on CT. Median value for volumetric rate in the embolized liver was 63.3% after the first PVE and 54.7% after the second (P < 0.01). Median functional rate value in embolized liver was 60.1% after the first PVE and 49.4% after the second (P < 0.01). Median value for change of volumetric and functional rates in embolized liver after the second PVE was 7.1 and 10.3%, respectively, and change of functional rate was greater than that of volumetric rate (P < 0.01).

Conclusions

^99mTc-GSA SPECT/CT fusion imaging was useful for detecting inadequate PVE, and second PVE was effective for increasing volumetric and functional rates.

     

Using <Superscript>99m</Superscript>Tc-DTPA radioaerosol inhalation lung scan as compared with computed tomography to detect lung injury in blunt chest trauma

Background

Detection of pulmonary contusion in patients with blunt chest trauma is very important so as to commence therapy immediately to avoid irreversible damage. The purpose of our study was to evaluate the efficacy of technetium-99m diethylene triamine pentaacetic acid (^99mTc-DTPA) aerosol inhalation lung scintigraphy in comparison with chest computed tomography (CT) in the diagnosis of pulmonary contusion at acute blunt chest trauma.

Methods

Twenty-nine patients with isolated blunt chest trauma were referred to the emergency department of our hospital, and nine healthy people participated in this study. Sixteen patients who had pulmonary contusion on CT scans were referred to as group 1, and 13 patients who had normal CT scans as group 2. Nine healthy people comprised a control group. ^99mTc-DTPA aerosol inhalation lung scintigraphy was performed on the first day in all patients.

Results

The mean half time (T_½) and penetration index values of ^99mTc-DTPA clearance were significantly lower in groups 1 and 2 compared with the control group. Among the three groups, there were no significant differences in arterial blood gas analysis except for PO₂. The mean T_½ value of ^99mTc-DTPA clearance did correlate with PO₂ values but not with pH, PCO₂, or HCO₃ values.

Conclusions

^99mTc-DTPA radioaerosol inhalation lung imaging may serve as a useful adjunct and supportive method to chest CT scanning for detecting mild pulmonary contusion.

     

Molecular imaging in musculoskeletal infections with <Superscript>99m</Superscript>Tc-UBI 29-41 SPECT/CT

Objective

To determine the added value of CT over planar and SPECT-only imaging in the diagnosis of musculoskeletal infection using ^99mTc-UBI 29-4.

Materials and methods

184 patients with suspected musculoskeletal infection who underwent planar and SPECT/CT imaging with ^99mTc-UBI 29-41 were included. Planar, SPECT-only and SPECT/CT images were reviewed by two independent analysts for presence of bone or soft tissue infection. Final diagnosis was confirmed with tissue cultures, surgery/histology or clinical follow-up.

Results

^99mTc-UBI 29-41 was true positive in 105/184 patients and true negative in 65/184 patients. When differentiating between soft tissue and bone infection, planar?+?SPECT-only imaging had a sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 95.0, 74.3, 84.8, 91.3 and 86.9%, respectively, versus 99.0, 94.5, 92.5, 98.5 and 94.5% for SPECT/CT. SPECT/CT resulted in a change in reviewers’ confidence in the final diagnosis in 91/184 patients. Inter-observer agreement was better with SPECT/CT compared with planar?+?SPECT imaging (kappa 0.87, 95% CI 0.71–0.85 versus kappa 0.81, 95% CI 0.58–0.75).

Conclusion

Addition of CT to planar and SPECT-only imaging led to an increase in diagnostic performance and an improvement in reviewers’ confidence and inter-observer agreement in differentiating bone from soft tissue infection.

     

<Superscript>18</Superscript>F-Fluorocholine PET/CT in the assessment of primary hyperparathyroidism compared with <Superscript>99m</Superscript>Tc-MIBI or <Superscript>99m</Superscript>Tc-tetrofosmin SPECT/CT: a prospective dual-centre study in 100 patients

Purpose

In this prospective study we compared the accuracy of ¹⁸F-fluorocholine PET/CT with that of ^99mTc-MIBI or^99mTc-tetrofosmin SPECT/CT in the preoperative detection of parathyroid adenoma in patients with primary hyperparathyroidism. We also assessed the value of semiquantitative parameters in differentiating between parathyroid hyperplasia and adenoma.

Methods

Both ¹⁸F-fluorocholine PET/CT and ^99mTc-MIBI/tetrofosmin SPECT/CT were performed in 100 consecutive patients with biochemical evidence of primary hyperparathyroidism. At least one abnormal focus on either ¹⁸F-fluorocholine or ^99mTc-MIBI/tetrofosmin corresponding to a parathyroid gland or ectopic parathyroid tissue was considered as a positive finding. In 76 patients with positive findings on at least one imaging modality, surgical exploration was performed within 6 months, and the results were related to histopathological findings and clinical and laboratory findings at 3–6 months as the standard of truth. In 24 patients, no surgery was performed: in 18 patients with positive imaging findings surgery was refused or considered risky, and in 6 patients imaging was negative. Therefore, data from 82 patients (76 undergoing surgery, 6 without surgery) in whom the standard of truth criteria were met, were used in the final analysis.

Results

All patients showed biochemical evidence of primary hyperparathyroidism with a mean serum calcium level of 2.78?±?0.34 mmol/l and parathormone (PTH) level of 196.5?±?236.4 pg/ml. The study results in 76 patients with verified histopathology and 3 patients with negative imaging findings were analysed. Three of six patients with negative imaging showed normalized serum PTH and calcium levels on laboratory follow-up at 3 and 6 months, and the results were considered true negative. In a patient-based analysis, the detection rate with ¹⁸F-fluorocholine PET/CT was 93% (76/82), but was only 61% (50/82) with ^99mTc-MIBI/tetrofosmin SPECT/CT. In a lesion-based analysis, the sensitivity, specificity, positive predictive value, negative predictive value and overall accuracy of ¹⁸F-fluorocholine PET/CT in the detection of parathyroid adenoma were 93.7%, 96.0%, 90.2%, 97.4% and 95.3%, respectively, and of ^99mTc-MIBI/tetrofosmin SPECT/CT were 60.8%, 98.5%, 94.1%, 86.3% and 87.7%, respectively. Although ¹⁸F-fluorocholine PET-positive adenomatous lesions showed higher SUVmax values than the hyperplastic glands (6.80?±?3.78 vs. 4.53?±?0.40) in the semiquantitative analysis, the difference was not significant (p?=?0.236). The mean size (measured as the length of the greatest dimension) and weight of adenomas were 15.9?±?7.6 mm (median 15 mm, range 1–40 mm) and 1.71?±?1.86 g (median 1 g, range: 0.25–9 g), respectively. Among the analysed parameters including serum calcium and PTH and the size and weight of parathyroid adenomas, size was significantly different between patients with negative ^99mTc-MIBI/tetrofosmin SPECT/CT and those with positive ^99mTc-MIBI/tetrofosmin SPECT/CT (mean size 13.4?±?7.6 mm vs. 16.9?±?7.4 mm, respectively; p?=?0.042).

Conclusion

In this prospective study, ¹⁸F-fluorocholine PET/CT showed promise as a functional imaging modality, being clearly superior to ^99mTc-MIBI/tetrofosmin SPECT/CT, especially in the detection and localization of small parathyroid adenomas in patients with primary hyperparathyroidism. SUVmax was higher in parathyroid adenomas than in hyperplasia. However, further evaluation of this modality is needed.

     

Clinical application of <Superscript>99m</Superscript>Tc-HYNIC-TOC SPECT/CT in diagnosing and monitoring of pancreatic neuroendocrine neoplasms

Objective

Our aim of this research was to determine the value of SPECT/CT with ^99mTc-HYNIC-TOC for evaluation of the pancreatic masses which were suspected as neuroendocrine neoplasms and follow-up of patients with pancreatic neuroendocrine neoplasms.

Methods

We retrospectively analyzed 184 patients who performed ^99mTc-HYNIC-TOC SPECT/CT. All the patients were divided into two groups: one for assessment of diagnostic efficiency for pancreatic suspected masses (n?=?140) and another for monitoring recurrence after surgery (n?=?44). The image findings acquired at 2 h postinjection were compared to final diagnoses from pathological results and clinical follow-up. Then, the correlation between ratios of tumor-to-background (TBR) and tumor grade was analyzed.

Results

In group 1, 95/140 (67.9%) patients were confirmed as neuroendocrine neoplasms including 85 neuroendocrine tumors and 10 neuroendocrine carcinomas. Patient-based analysis showed that the sensitivity, specificity and accuracy of diagnosing neuroendocrine neoplasms with SPECT/CT were 81.1, 84.4 and 82.1%. There was significant difference of TBRs among G1, G2 and G3 (F?=?3.175, P?=?0.048). In group 2, 22/44 (50.0%) patients occurred metastasis mainly in liver. The sensitivity, specificity and accuracy of monitoring recurrence were 87.0, 100 and 93.2%.

Conclusions

^99mTc-HYNIC-TOC SPECT/CT is a reliable method of diagnosing and monitoring of pancreatic neuroendocrine neoplasms, especially neuroendocrine tumors.

     

First ex vivo study demonstrating that <Superscript>99m</Superscript>Tc-NTP 15-5 radiotracer binds to human articular cartilage

Purpose  

Preclinical data pointed to ^99mTc-NTP 15-5 as a good candidate for single photon emission computed tomography (SPECT) imaging of cartilaginous disease. We set out to investigate and quantify ^99mTc-NTP 15-5 ex vivo uptake by human articular cartilage relative to bone ^99mTc-hydroxymethylene diphosphonate (HMDP) radiotracer.     

<Superscript>18</Superscript>F-FDG PET independently predicts survival in patients with cholangiocellular carcinoma treated with <Superscript>90</Superscript>Y microspheres

Purpose  

⁹⁰Y radioembolization has emerged as a valuable therapy for intrahepatic cholangiocellular carcinomas (ICC). We aimed to evaluate the prognostic power of FDG PET/CT and that of pretherapeutic scintigraphy with ^99mTc-labelled macroagglutinated albumin (MAA), an index of tumour vascularization.     

Comparison of hybrid <Superscript>68</Superscript>Ga-PSMA-PET/CT and <Superscript>99m</Superscript>Tc-DPD-SPECT/CT for the detection of bone metastases in prostate cancer patients: <Emphasis Type="Italic">Additional value of morphologic information from low dose CT</Emphasis>

Purpose

This study compared ⁶⁸Gallium-prostate-specific-membrane-antigen based Positron-emission-tomography (⁶⁸Ga-PSMA-PET) and ^99metastabletechnetium-3,3-diphospho-1,2-propanedicarbonacid (^99mTc-DPD-SPECT) in performing skeletal staging in prostate cancer (PC) patients and evaluated the additional value of the information from low-dose-computed tomography (CT).

Materials and Methods

In this retrospective study, 54 patients who received ⁶⁸Ga-PSMA-PET/CT and ^99mTc-DPD-SPECT/CT within 80 days were extracted from our database. Osseous lesions were classified as benign, malignant or equivocal. Lesion, region and patient based analysis was performed with and without CT fusion. The reference standard was generated by defining a best valuable comparator (BVC) containing information from all available data.

Results

In the patient based analysis, accuracies measured as “area-under-the-curve” (AUC) for ⁶⁸Ga-PSMA-PET, ^99mTc-SPECT, ⁶⁸Ga-PSMA-PET/CT and ^99mTc-SPECT/CT were 0.97-0.96, 0.86-0.83, 1.00 and 0.83, respectively (p<0.05) (ranges = optimistic vs. pessimistic view). Region based analysis resulted in the following sensitivities and specificities: 91.8-97.7%, 100-99.5% (PET); 61.2-70.6%, 99.8-98.3% (SPECT); 97.7%, 100% (PET/CT), 69.4% and 98.3% (SPECT/CT) (p<0.05). The amount of correct classifications of equivocal lesions by CT was significantly higher in PET (100%) compared to SPECT (52.4%) (p<0.05).

Conclusion

⁶⁸Ga-PSMA-PET outperforms ^99mTc-DPD-SPECT in detecting bone metastases in PC patients. Additional information from low-dose-CT resulted in a significant reduction in equivocal lesions in both modalities, however ⁶⁸Ga-PSMA-PET benefited most.

Key Points

? Ga-PSMA-PET outperforms ^99m Tc-DPD-SPECT in skeletal staging in prostate cancer patients ? Proportion of equivocal decisions was significantly reduced by CT-fusion in both modalities ? Ga-PSMA-PET benefits more from CT information, compared to ^99m Tc-DPD-SPECT

     

Efficacy of 99mTc-sestamibi SPECT/CT for minimally invasive parathyroidectomy: comparative study with 99mTc-sestamibi scintigraphy, SPECT, US and CT

Purpose

We evaluated the efficacy of ^99mTc-sestamibi SPECT/CT for planning minimally invasive parathyroidectomy (MIP), comparing with dual phase ^99mTc-sestamibi scintigraphy, ^99mTc-sestamibi SPECT and conventional imaging (US and CT).

Methods

Thirty-one patients (M:F?=?10:21, range 35?C78?years old) who showed high serum parathyroid hormone (intact PTH) level were included. ^99mTc-sestamibi scintigraphy was performed 15 and 150?min after injection of ^99mTc-sestamibi (555?MBq), and ^99mTc-sestamibi SPECT/CT was obtained just after the delayed scan. Comparison study between imaging modalities was done by patient-based and lesion location-based analysis. The location of the lesion was confirmed by the operative finding. An operation was performed in 24 patients. Seven patients had normal ^99mTc-sestamibi SPECT/CT, and followed for more than 6?months after SPECT/CT.

Results

Among 24 patients, parathyroid adenoma was detected in 19 patients and the other 5 had parathyroid hyperplasia (total 35 lesions). ^99mTc-sestamibi scintigraphy detected abnormal uptake in 15 patients with 24 lesions. Conventional imaging identified abnormal findings in 17 patients with 27 lesions. SPECT detected abnormal findings in 18 patients with 27 lesions. SPECT/CT identified abnormal findings in 24 patients with 35 lesions. SPECT/CT demonstrated 100?% sensitivity in a patient-based analysis. SPECT/CT exhibited significantly better sensitivity than ^99mTc-sestamibi scintigraphy, SPECT and conventional imaging (p?<?0.05). All lesion location was correctly identified to perform MIP. The final clinical diagnosis of 7 normal SPECT/CT patients was secondary hyperparathyroidism on 6?months follow-up.

Conclusions

We correctly identified the precise location of parathyroid adenomas or hyperplasia by ^99mTc-sestamibi SPECT/CT which was helpful to perform MIP.     

<Superscript>99m</Superscript>Tc-GSA SPECT/CT fusion imaging for hepatectomy candidates with extremely deteriorated ICG value

Purpose

The value of indocyanine green (ICG) test is negatively affected in patients with intrahepatic shunt, ICG excretory defect, or jaundice. This study evaluated ^99mTc-GSA SPECT/CT fusion imaging for assessing liver function in patients with severely deteriorated ICG values.

Materials and methods

Thirteen hepatectomy candidates with ICG retention rates over 40% were retrospectively analyzed. The ICG clearance rate (KICG) and estimated KICG obtained by ^99mTc-GSA scintigraphy (KGSA) were used to evaluate preoperative whole liver function. Remnant liver function was assessed using the remnant (rem) KICG (=?KICG?×?volumetric rate) and remKGSA (=?KGSA?×?functional rate) indices; hepatectomy was considered unsafe for values <?0.05. The correlations of remKICG and remKGSA with postoperative mortality and morbidity were also investigated.

Results

KGSA values were significantly greater than KICG values (median: 0.12 vs. 0.059; p?<?0.01); remKGSA values were greater than remKICG values in all patients (median: 0.107 vs. 0.0413; p?<?0.01). Hepatectomy was considered unsafe in 70% patients using remKICG, and in none of those using remKGSA; liver failure or postoperative mortality did not occur.

Conclusions

^99mTc-GSA SPECT/CT fusion imaging enables more accurate liver function assessment than the ICG test in patients with severely deteriorated ICG values.

     

Clinical evaluation of SPECT/CT fusion imaging for the diagnosis and determination of localisation of cerebrospinal rhinorrhea

ObjectiveThe objective was to evaluate the clinical value of the single photon emission computerized tomography/computed tomography (SPECT/CT) fusion imaging for the diagnosis and determination of localisation of cerebrospinal rhinorrhea.MethodsA total of 33 patients with cerebrospinal rhinorrhea were preoperatively injected with ^99mTc-diethylenetriamine pentaacetic acid (DTPA) through lumbar puncture and then subjected to planar imaging of the cistern 120 min and 180 min after operation. CT and ECT were then performed. Finally, the rhinorrhea ventage and leaking path were confirmed by fusion image analysis.ResultsThirty-one patients who underwent fusion imaging and 30 patients who underwent planar imaging showed abnormal nuclide activity in the cavity between the basis cranii and the nose. After operation, 30 patients who underwent fusion imaging and 18 patients who underwent planar imaging showed complete correction of the leakage. The diagnosis sensitivity and positional accuracy of fusion imaging were 93.9% (31/33) and 90.9% (30/33) at P> .05. The values of planar imaging were 93.5% (29/31) and 79.3% (23/29) at P< .05.Conclusion^99mTc-DTPA SPECT/CT fusion imaging of the cistern is an efficient, simple, and accurate method that may be used for diagnosing and determining the localisation of cerebrospinal rhinorrhea ventage and leakage path.     

Single-photon emission CT using 99mTc-dimercaptosuccinic acid (DMSA) for characterization of suspected renal masses

Objective:

A retrospective analysis of the clinical utility of ^99mTc-dimercaptosuccinic acid (DMSA) single photon emission CT (SPECT) for characterization of suspected renal masses.

Methods:

15 patients who had undergone ^99mTc-DMSA SPECT were identified, and 13 patients also had SPECT/CT. ^99mTc-DMSA uptake in the renal lesion was characterized semiquantitatively. Other imaging tests, histology and clinical data were available for correlation.

Results:

^99mTc-DMSA was not taken up in all five renal masses with histological confirmation of malignancy (uptake 7–19% of normal renal tissue); in two further masses, which were clinically likely to be malignant; and in one indeterminate mass (lack of sufficiently long follow-up). No renal malignancy was identified in any of the seven patients whose renal masses had normal ^99mTc-DMSA uptake (41–130%).

Conclusion:

Although caution with regard to applying those results in clinical practice must be advised, owing to the retrospective nature of this report and the small number of patients included, it seems that ^99mTc-DMSA SPECT shows a clinically useful diagnostic accuracy for distinguishing true renal masses (which in many cases require surgery) from pseudomasses.

Advances in knowledge:

^99mTc-DMSA SPECT is a clinically useful adjunct test for characterization of suspected renal masses.^99mTc-labelled 2,3-dimercaptosuccinic acid (DMSA) has been the standard radiopharmaceutical for static renal scintigraphy for many years.¹ It has a high degree of plasma protein binding (76%). Its main metabolic pathway first involves glomerular filtration, followed by tubular reabsorption, with minimal urinary excretion (5%).² In adults, its foremost clinical use is to determine differential renal function, but also to image ectopic renal tissue.³We have occasionally used ^99mTc-DMSA scans to establish whether a suspected renal mass or pseudomass contains functioning renal tissue or not. Such use is acknowledged in a respected textbook,⁴ stating that “for many years ^99mTc-DMSA with or without single-photon emission CT (SPECT) was used as a problem-solving technique to differentiate a space-occupying solid mass from a column of Bertin…”. However, we were surprised to be able to identify only a small number of publications reporting the use of ^99mTc-DMSA SPECT for this purpose in a series of patients.^5,6This article reports the results of ^99mTc-DMSA SPECT in 15 patients referred for evaluation of a suspected renal mass from our case archive.     

99mTc-DTPA and 99mTc-DMSA renal gamma imaging in the surveillance of patients with conduit urinary diversion

We studied renal anatomy and function using ^99mTc-2-3 dimercaptosuccinic acid (DMSA) and ^99mTc-diethylenetriaminepentaacetic acid (DTPA) in 27 patients with conduit urinary diversion. In this condition, free ureteral reflux is often associated with bacteriuria, and these factors are thought to precipitate progressive renal deterioration. Gamma-camera images provided valuable information concerning the structure of the renal parenchyma, the function of individual kidneys and possible ureteral obstruction, thus helping us to decide whether or not to instigate further treatment. The information gained using renal gamma imaging with ^99mTc-DTPA and ^99mTc-DMSA was complementary and partly overlapping. We preferred the use of ^99mTc-DTPA because of its ability to visualise the ureters and the region of ureteroconduit anastomosis. Using diuretic medication, we were able to differentiate true ureteral obstruction from atony in 9 patients using ^99mTc-DTPA.     

Influence of hilar deposition in the evaluation of the alveolar epithelial permeability on <Superscript>99m</Superscript>Tc-DTPA aerosol inhaled scintigraphy

Purpose

We investigated whether hilar radioaerosol deposition affects the clearance rate of technetium-99m-labeled diethylenetriaminepentaacetic acid (^99mTc-DTPA) from peripheral alveolar regions.

Materials and methods

A total of 38 patients underwent ^99mTc-DTPA inhalation lung scintigraphy. Six region of interest (ROI) patterns were adopted: ROI 1 was outlined around the entire hemithorax, and ROIs 2–6 were outlined around the hemithorax but excluded square ROIs of different size in the hilar region. Half-times (T_½) were calculated with time-activity curves using onecompartment and two-compartment analyses. The T_½ of ROIs 1–5 were plotted against the T_½ of ROI 6, and regression lines were obtained with the least-squares method. The absolute values of the differences between surveyed values and regression line were calculated. The Wilcoxon test for trend and a single linear regression model were used to determine statistical significance.

Results

There were significant reductions in the absolute values of the differences between surveyed values and regression line from ROIs 1–5 by one-component analysis and the fast component of two-compartment analysis (P < 0.001).

Conclusion

Our results suggest that the deposition of radioaerosol in the hilar region affects the clearance rate of ^99mTc-DTPA from the alveoli in damaged lungs. The hilar region should be excluded from ROIs when alveolar epithelial permeability is evaluated.

     

Glomerular filtration rate in relation to extracellular fluid volume: Similarity between99mTc-DTPA and inulin

The rate constant ( ₂) of the terminal exponential of the technetium-99m diethylene triamine pentaacetic acid (DTPA) plasma clearance curve is close to the ratio of glomerular filtration rate (GFR) to extracellular fluid volume (ECV) and is therefore a convenient, already normalised, measure of filtration function. Since ₂ depends on the distribution volume of the tracer, our aim was to compare ₂ from inulin and^99mTc-DTPA and also to compare the equilibration kinetics of the two filtration markers. Fifty millititres of^99mTc-DTPA (250 MBq) and inulin (10%), mixed in the same syringe, were given by intravenous injection in 15 patients undergoing routine^99mTc-DTPA renography for a variety of clinical indications. Frequent antecubital venous blood samples were taken up to about 4 h after injection to construct plasma clearance curves from which GFR, ECV and GFR/ECV (i.e. the reciprocal of mean transit time through the distribution volume) were calculated.^99mTc-DTPA/inulin concentration ratio curves were also constructed after normalisation to the ratio in the syringe. GFR given by the two markers correlated closely (DTPA=0.98·inulin—0.4ml/min;r=0.98).^99mTc-DTPA had the same distribution volume as inulin, had a similar transit time through it and gave the same value of ₂ (r=0.98). GFR/ECV from^99mTc-DTPA accordingly correlated closely with GFR/ECV from inulin (DTPA=0.75·inulin+0.99 ml/min;r=0.95). Even though the distribution volumes and the times to equilibration (i.e. to reach the terminal exponential) were similar, the distribution volume of^99mTc-DTPA at about 10 min after injection was, after subtraction of the plasma volume, about twice that of inulin.We confirm the validity of^99mTc-DTPA for measuring GFR. ₂ is a convenient measure of GFR, can be based on the terminal exponential of inulin of^99mTc-DTPA curves and can be converted to GFR/ECV with an appropriate scaling factor. The kinetics or the two clearance curves with respect to anatomical correlates of the exponentials and the rates of diffusion throughout the respective distribution volumes requires further study.     

Usefulness of SPECT/CT in Parathyroid Lesion Detection in Patients with Thyroid Parenchymal <Superscript>99m</Superscript>Tc-Sestamibi Retention

Purpose

Parathyroid adenoma detection with dual-phase ^99mTc-sestamibi (MIBI) scintigraphy depends on differential MIBI washout from thyroid. However, autoimmune thyroid disease (AITD) may cause MIBI to be retained in the thyroid gland and reduce parathyroid detection. We evaluated the impact of AITD on MIBI thyroid retention and additional benefit of SPECT/CT in these patients.

Methods

Dual phase planar MIBI and SPECT/CT was performed on 82 patients. SPECT/CT was performed immediately after delayed planar scan. Thyroid density (Hounsfield unit, CT-HU) and size were measured on CT component of SPECT/CT. MIBI uptake in early scans and retention in delayed scans were visually graded and correlated with clinical factors and CT findings. Finally, planar and SPECT/CT findings were compared for parathyroid lesion visualization according to thyroid MIBI retention.

Results

In early scan, multivariate analysis showed only thyroid size predicted early uptake. In delayed scan, multivariate analysis showed higher visual grade in early scan, lower CT-HU or AITD were significant predictors for delayed thyroid parenchymal retention. Overall, ten more parathyroid lesions were visualized on SPECT/CT compared to planar scans (57 vs. 47, p?=?0.002). SPECT/CT was especially more useful in patients with thyroidal MIBI retention, as eight out of the ten additional lesions detected were found in patients with thyroid MIBI retention.

Conclusion

AITD is an important factor for MIBI thyroid parenchymal retention on delayed scans, and may impede parathyroid lesion detection. Patients with MIBI retention in the thyroid parenchyma on delayed scans are likely to benefit from an additional SPECT/CT.

     

Left ventricular mechanical synchrony from stress and rest <Superscript>82</Superscript>Rb PET myocardial perfusion ECG-gated studies: Differentiating normal from LBBB patients

Background  

We have previously reported normal values for LV mechanical synchrony from post-stress exercise ^99mTc SPECT studies; the goal of this study was to develop normal values for mechanical synchrony from pharmacologic stress and rest ⁸²Rb PET studies and compare these values to a population of LBBB patients.     

Accurate assessment of long-term nephrotoxicity after peptide receptor radionuclide therapy with 177Lu-octreotate

Purpose

Renal radiation during peptide receptor radionuclide therapy (PRRT) may result in glomerular damage, a potential reduction of glomerular filtration rate (GFR) and ultimately lead to renal failure. While reported PRRT nephrotoxicity is limited to data derived from serum creatinine—allowing only approximate estimates of GFR—the aim of this study is to accurately determine PRRT-induced long-term changes of renal function and associated risk factors according to state-of-the-art GFR measurement.

Methods

Nephrotoxicity was analysed using ^99mTc-diethylenetriaminepentaacetic acid (DTPA) clearance data of 74 consecutive patients with gastroenteropancreatic neuroendocrine tumours (GEP NET) undergoing PRRT with ¹⁷⁷Lu-octreotate. The mean follow-up period was 21 months (range 12–50) with a median of five GFR measurements per patient. The change of GFR was analysed by linear curve fit. Potential risk factors including diabetes mellitus, arterial hypertension, previous chemotherapy, renal impairment at baseline and cumulative administered activity were analysed regarding potential impact on renal function loss. In addition, Common Terminology Criteria for Adverse Events (CTCAE) v3.0 were used to compare nephrotoxicity determined by ^99mTc-DTPA clearance versus serum creatinine.

Results

The alteration in GFR differed widely among the patients (mean ?2.1?±?13.1 ml/min/m² per year, relative yearly reduction ?1.8?±?18.9 %). Fifteen patients (21 %) experienced a mild (2–10 ml/min/m² per year) and 16 patients (22 %) a significant (>10 ml/min/m² per year) decline of GFR following PRRT. However, 11 patients (15 %) showed an increase of >10 ml/min/m² per year. Relevant nephrotoxicity according to CTCAE (grade ≥3) was observed in one patient (1.3 %) with arterial hypertension and history of chemotherapy. Nephrotoxicity according to serum creatinine was discordant to that defined by GFR in 15 % of the assessments and led to underestimation in 12 % of patients. None of the investigated factors including cumulative administered activity contributed to the decline of renal function.

Conclusion

Serious nephrotoxicity after PRRT with ¹⁷⁷Lu-octreotate is rare (1.3 %). However, slight renal impairment (GFR loss >2 ml/min/m² per year) can frequently (43 %) be detected by ^99mTc-DTPA clearance assessments. Cumulative administered activity of ¹⁷⁷Lu-octreotate is not a major determinant of renal impairment in our study.