Case report: A fatal case of myocardial infarction due to myocardial bridge and concomitant vasospasm: the role of stress gated SPECT

Introduction

Although most cases of myocardial bridge (MB) are clinically benign, sometimes it can be one of potential threats of myocardial infarction (MI) and life-threatening arrhythmia. In the present study, we present a case of ST-segment elevation MI caused by MB and concomitant vasospasm.

Case Presentation

A 52-year-old woman was brought to our tertiary hospital due to resuscitated cardiac arrest. Because the 12-lead electrocardiogram indicated ST-segment elevation MI, coronary angiogram was promptly commenced, which showed near-total occlusion at the middle portion of left anterior descending coronary artery (LAD). After intracoronary nitroglycerin administration, this occlusion was dramatically relieved, however, systolic compression at this site remained, indicative of myocardial bridge (MB). Intravascular ultrasound also showed eccentric compression with a "half-moon" sign, which is consistent with MB. Coronary computed tomography also showed a bridged coronary segment surrounded by myocardium at the middle portion of LAD. To assess the severity and extent of myocardial damages and ischemia, myocardial single photon emission computed tomography (SPECT) was additionally conducted, showing a moderate fixed perfusion defect around the cardiac apex, suggesting MI. After receiving optimal medical therapy, the patient's clinical symptoms and signs were improved then the patient was discharged from the hospital successfully and uneventfully.

Conclusion

We demonstrated a case of MB-induced ST-segment elevation MI which was confirmed with its perfusion defects via myocardial perfusion SPECT. There have been proposed a number of diagnostic modalities to examine its anatomic and physiologic significance. Among them, myocardial perfusion SPECT can be available as one of useful modalities to evaluate the severity and extent of myocardial ischemia in patients with MB.

Diagnostic performance of SPECT-CT imaging in unilateral condylar hyperplasia

Nuclear imaging plays an important role in the diagnostic path of patients with unilateral condylar hyperplasia (UCH). The purpose of this study was to determine the performance of single-photon emission computed tomography-computed tomography (SPECT-CT) in a large group of patients with suspected UCH. This study prospectively included 156 patients with a clinical presentation of progressive mandibular asymmetry. All patients underwent ^99 mTc-HDP SPECT-CT and extensive baseline and follow-up documentation. The relative activity of the ipsilateral condyle in relation to the contralateral condyle was calculated for both the mean and maximum count, and the diagnostic accuracy of different cut-off values was determined. The area under the receiver operating characteristic curve of the SPECT-CT scan was 0.892 for the mean count and 0.873 for the maximum count. The optimal cut-off of> 8% (SPECT-CT mean count) resulted in a sensitivity of 87.0% and a specificity of 88.6%. SPECT-CT showed good diagnostic performance in UCH; however the benefit of the CT scan is questionable and the potential disadvantages have to be weighed against the benefits when compared to standard SPECT scanning. When using SPECT-CT in the diagnostic path in UCH, a mean value cut-off of>8% for the relative activity between the condyles is most accurate.

Incidental Findings of Malignancy of the Chest by Single Photon Emission Computed Tomography Myocardial Perfusion Imaging (SPECT-CT MPI): One Year Follow-Up Report

Introduction

We recently reported six cases of pulmonary/hilar malignancies as the result of incidental findings (IF) on CT attenuation correction (CTAC) during Single Photon Emission Computed Tomography Myocardial Perfusion Imaging (SPECT-CT MPI). In this study, clinical features, diagnostic procedures, and clinical outcomes were examined on all patients who had malignancies or significant IF that required further follow-up.

Methods

Of 1,098 consecutive patients who underwent cardiac SPECT-CT MPI from September 1, 2017 to August 31, 2018, their MPI and CTAC were reviewed contemporaneously. Patients with known history of prior pulmonary or chest malignancy were excluded.

Results

A total of 79 (7.2%) patients were identified to have significant IF on CTAC. After diagnostic CT, 47 patients had significant findings that warranted further follow-up and included in this study. Eight of 1,098 patients (0.73%) and 8/79 patients (10.1%) were found to have malignancy of the chest because of IF on the CTAC. There were no statistically significant differences in baseline characteristics and cancer risk factors among patients who had cancer versus those without. At the time of diagnosis, four patients had cancer at an advanced stage, resulting in death within 12 months. Three others had early stage lung cancer and one had mantle cell lymphoma; they were alive at a mean follow-up of 17.5+/−2.1 months. Biopsy for tissue diagnosis was performed safely with needle biopsy. Major complication occurred in one patient (1/9 or 11.1%) with needle biopsy; none with surgical biopsy.

Conclusion

This study underscored the importance of reviewing CTAC images obtained during cardiac SPECT-CT MPI to detect clinically important IF.

Comparison of perfused volume segmentation between cone-beam CT and 99mTc-MAA SPECT/CT for treatment dosimetry before selective internal radiation therapy using 90Y-glass microspheres

PURPOSE

To compare the reliability and accuracy of the pre-treatment dosimetry predictions using cone-beam computed tomography (CBCT) versus ^99mTc-labeled macroaggregated albumin (MAA) SPECT/CT for perfused volume segmentation in patients with hepatocellular carcinoma treated by selective internal radiation therapy (SIRT) using ⁹⁰Y-glass microspheres.

MATERIALS AND METHODS

Fifteen patients (8 men, 7 women) with a mean age of 68.3±10.5 (SD) years (range: 47-82 years) who underwent a total of 17 SIRT procedures using ⁹⁰Y-glass microspheres for unresectable hepatocellular carcinoma were retrospectively included. Pre-treatment dosimetry data were calculated from ^99mTc-MAA SPECT/CT using either CBCT or ^99mTc-MAA SPECT/CT to segment the perfused volumes. Post-treatment dosimetry data were calculated using ⁹⁰Y imaging (SPECT/CT or PET/CT). The whole liver, non-tumoral liver, and tumor volumes were segmented on CT or MRI data. The mean absorbed doses of the tumor (D_T), non-tumoral liver, perfused liver (D_PL) and perfused non-tumoral liver were calculated. Intra- and interobserver reliabilities were investigated by calculating Lin's concordant correlation coefficients (ρ_c values). The differences (biases) between pre- and post-treatment dosimetry data were assessed using the modified Bland-Altman method (for non-normally distributed variables), and systematic bias was evaluated using Passing-Bablok regression.

RESULTS

The intra- and interobserver reliabilities were good-to-excellent (ρ_c: 0.80-0.99) for all measures using both methods. Compared with 90Y imaging, the median differences were 5.8Gy (IQR: -12.7; 16.1) and 5.6Gy (IQR: -13.6; 10.2) for D_PL-CBCT and D_PL-^99mTc-MAA SPECT/CT, respectively. The median differences were 1.6Gy (IQR: -29; 7.53) and 9.8Gy (IQR: -28.4; 19.9) for D_T-CBCT and D_T-^99mTc-MAA SPECT/CT respectively. Passing-Bablok regression analysis showed that both CBCT and ^99mTc-MAA SPECT/CT had proportional biases and thus tendencies to overestimate D_T and D_PL at higher post-treatment doses.

CONCLUSION

CBCT may be a reliable segmentation method, but it does not significantly increase the accuracy of dose prediction compared with that of ^99mTc-MAA SPECT/CT. At higher doses both methods tend to overestimate the doses to tumors and perfused livers.

Radiopharmaceuticals for Treatment of Osteosarcoma

Although trace amounts of radioactivity are routinely used to detect osteosarcoma, the use of larger therapeutic amounts of radiation is often an unrecognized opportunity to treat metastatic osteosarcoma. This chapter will review a number of approaches to use ionizing radiation in the form of injectable radiopharmaceuticals. Since bone metastases are a common pattern of metastatic spread of cancer in general, a number of bone-seeking radiopharmaceuticals have been developed and FDA approved for treatment of bone metastases. Although osteosarcoma, a bone-forming cancer, would seem ideally suited to be treated with bone seekers, patterns of relapse involving non-ossifying metastases remain a major problem to be overcome. Thus, this review will not only describe experience using a number of bone-seeking radiopharmaceuticals such as 153-samarium-EDTMP, 153-samarium-DOTMP, and 223-radium against osteosarcoma, but also approaches to identify patients who may benefit as well as some means to the improve overall efficacy including combination therapy with routine agents and using nuclear imaging to develop best strategy for use. These include imaging with not only ^99mTc-MDP standard bone scans, but also ^99mTc-MDP bone scans with SPECT CT, bone-specific sodium fluoride PET-CT (Na¹⁸F), and ¹⁸FDG-PET-CT. Accurate knowledge of oligometastatic active disease can facilitate more effective use of combination therapy, including radiosensitizers and local control measures, for example, stereotactic body radiotherapy (SBRT) and/or cryoablation to reduce disease burden as well as manage and prevent micrometastatic disease from growing and metastasizing. Finally, a new tumor-specific radiopharmaceutical, CLR 131, may also provide another radiopharmaceutical to treat both osteoblastic and non-ossifying areas of osteosarcoma.

Iterative CT reconstruction in abdominal low-dose CT used for hybrid SPECT-CT applications: effect on image quality, image noise, detectability, and reader's confidence

Background

Iterative computed tomography (CT) image reconstruction shows high potential for the preservation of image quality in diagnostic CT while reducing patients’ exposure; it has become available for low-dose CT (LD-CT) in high-end hybrid imaging systems (e.g. single-photon emission computed tomography [SPECT]-CT).

Purpose

To examine the effect of an iterative CT reconstruction algorithm on image quality, image noise, detectability, and the reader’s confidence for LD-CT data by a subjective assessment.

Material and Methods

The LD-CT data were validated for 40 patients examined by an abdominal hybrid SPECT-CT (U = 120 kV, I = 40 mA, pitch = 1.375). LD-CT was reconstructed using either filtered back projection (FBP) or an iterative image reconstruction algorithm (Adaptive Statistical Iterative Reconstruction [ASIR]®) with different parameters (ASIR levels 50% and 100%). The data were validated by two independent blinded readers using a scoring system for image quality, image noise, detectability, and reader confidence, for a predefined set of 16 anatomic substructures.

Results

The image quality was significantly improved by iterative reconstruction of the LD-CT data compared with FBP (P ≤ 0.0001). While detectability increased in only 2/16 structures (P ≤ 0.03), the reader’s confidence increased significantly due to iterative reconstruction (P ≤ 0.002). Meanwhile, at the ASIR level of 100%, the detectability in bone structure was highly reduced (P = 0.003).

Conclusion

An ASIR level of 50% represents a good compromise in abdominal LD-CT image reconstruction. The specific ASIR level improved image quality (reduced image noise) and reader confidence, while preserving detectability of bone structure.

Distribution of bone tracer uptake in symptomatic knees after ACL reconstruction compared to asymptomatic non-operated knees: a method for better differentiating patient-specific from disease-specific bone tracer uptake in SPECT/CT

OBJECTIVE

To evaluate the differences of bone tracer uptake (BTU) in symptomatic and asymptomatic contralateral knees in patients after reconstruction of the anterior cruciate ligament (ACL-R) and to identify typical BTU patterns and threshold values to differentiate pathological from physiological BTU.

METHODS

53 patients after unilateral ACL-R were retrospectively included in the study. The population was subdivided into a group of symptomatic operated knees and a group of contralateral asymptomatic non-operated knees. BTU was measured in SPECT/CT using a validated anatomical localization-scheme and normalized mean BTU values were calculated in both knees. Wilcoxon signed rank-test and Pearson's rank-correlation coefficient were used (p < 0.05).

RESULTS

Symptomatic knees after ACL-R showed significantly more BTU than asymptomatic ones (p < 0.01).Based on the measured BTU activity in SPECT/CT in symptomatic operated and asymptomatic non-operated knees, intensity thresholds of pathological BTU were established. A BTU threshold of greater than the Median + 1 SD of the asymptomatic non-operated knee was defined as pathological. In both groups the highest mean BTU was found on the femoral, tibial and patellar articular surfaces, the lowest BTU in femoral and tibial regions far from the joint.

CONCLUSIONS

The established BTU thresholds for SPECT/CT in knees after ACL-R help to differentiate disease-specific from patient-specific BTU. It could be speculated that BTU in asymptomatic knees equates to the preoperative condition of the knee joint before ACL-R. Therefore, the results of this study help to understand in-vivo loading of the knee and ultimately lead to prediction of development of osteoarthritis in an early stage.

Bone scintigraphy in patients with pain

Nuclear medicine imaging is widely used in pain medicine. Low back pain is commonly encountered by physicians, with its prevalence from 49% to 70%. Computed tomography (CT) or magnetic resonance imaging (MRI) are usually used to evaluate the cause of low back pain, however, these findings from these scans could also be observed in asymptomatic patients. Bone scintigraphy has an additional value in patients with low back pain. Complex regional pain syndrome (CRPS) is defined as a painful disorder of the extremities, which is characterized by sensory, autonomic, vasomotor, and trophic disturbances. To assist the diagnosis of CRPS, three-phase bone scintigraphy is thought to be superior compared to other modalities, and could be used to rule out CRPS due to its high specificity. Studies regarding the effect of bone scintigraphy in patients with extremity pain have not been widely conducted. Ultrasound, CT and MRI are widely used imaging modalities for evaluating extremity pain. However, SPECT/CT has an additional role in assessing pain in the extremities.

111 In-pentetreotide SPECT CT Value in Follow-up of Patients with Neuro-Endocrine Tumors

Carcinoid tumors are relatively rare and can occur in the thorax, abdomen, or pelvis. Functional imaging in the form of Indium-111 pentetreotide scanning is widely used for identification of these tumors and it exploits the fact that the vast majority of these tumors express somatostatin receptors on their cell membrane. In this report, we present a case of a 76-year-old man who was diagnosed with peritoneal carcinomatosis. The findings of the initial imaging made by planar and single photon emission computed tomography were misleading and the actual diagnosis was only made by single photon emission computed tomography/computed tomography.

Clinical utility of indigenously formulated single-vial lyophilized HYNIC-TOC kit in evaluating Gastro-entero Pancreatic neuro endocrine tumours

OBJECTIVES

The objective of this study was to evaluate the performance and utility of (99m)Tc HYNIC-TOC planar scintigraphy and SPECT/CT in the diagnosis, staging and management of gastroenteropancreatic neuroendocrine tumors (GPNETs).

METHODS

22 patients (median age, 46 years) with histologically proven gastro- entero- pancreatic NETs underwent (99m)Tc HYNIC-TOC whole body scintigraphy and regional SPECT/CT as indicated. Scanning was performed after injection of 370-550 MBq (10-15 mCi) of (99m)Tc HYNIC-TOC intravenously. Images were evaluated by two experienced nuclear medicine physicians both qualitatively as well as semi quantitatively (tumor to background and tumor to normal liver ratios on SPECT -CT images). Results of SPECT/CT were compared with the results of conventional imaging. Histopathology results and follow-up somatostatin receptor scintigraphy with (99m)Tc HYNIC TOC or conventional imaging with biochemical markers were considered to be the reference standards.

RESULTS

(99m)Tc HYNIC TOC showed sensitivity and specificity of 87.5% and 85.7%, respectively, for primary tumor and 100% and 86% for metastases. It was better than conventional imaging modalities for the detection of both primary tumor (P<0.001) and metastases (P<0.0001). It changed the management strategy in 6 patients (31.8%) and supported management decisions in 8 patients (36.3%).

CONCLUSION

(99m)Tc HYNIC TOC SPECT/CT appears to be a highly sensitive and specific modality for the detection and staging of GPNETs. It is better than conventional imaging for the evaluation of GPNETs and can have a significant impact on patient management and planning further therapeutic options.

Scintigraphic assessment of bone status at one year following hip resurfacing: Comparison of two surgical approaches using SPECT-CT scan

Objectives

To study the vascularity and bone metabolism of the femoral head/neck following hip resurfacing arthroplasty, and to use these results to compare the posterior and the trochanteric-flip approaches.

Methods

In our previous work, we reported changes to intra-operative blood flow during hip resurfacing arthroplasty comparing two surgical approaches. In this study, we report the vascularity and the metabolic bone function in the proximal femur in these same patients at one year after the surgery. Vascularity and bone function was assessed using scintigraphic techniques. Of the 13 patients who agreed to take part, eight had their arthroplasty through a posterior approach and five through a trochanteric-flip approach.

Results

One year after surgery, we found no difference in the vascularity (vascular phase) and metabolic bone function (delayed phase) at the junction of the femoral head/neck between the two groups of patients. Higher radiopharmaceutical uptake was found in the region of the greater trochanter in the trochanteric-flip group, related to the healing osteotomy.

Conclusions

Our findings using scintigraphic techniques suggest that the greater intra-operative reduction in blood flow to the junction of the femoral head/neck, which is seen with the posterior approach compared with trochanteric flip, does not result in any difference in vascularity or metabolic bone function one year after surgery.