Technetium-99m-pyrophosphate imaging-based computed tomography-guided core-needle biopsy of internal oblique muscle in wild-type transthyretin cardiac amyloidosis.

BACKGROUND: Technetium-99m-pyrophosphate (99mTc-PYP) uptake in the internal oblique muscle (IOM), which is often observed in patients with wild-type transthyretin cardiac amyloidosis (ATTR-CA), indicates amyloid transthyretin (ATTR) deposition. OBJECTIVE: This study aimed to assess the safety and efficacy of 99mTc-PYP imaging-based computed tomography (CT)-guided core-needle biopsy of the IOM as a new extracardiac screening biopsy for confirming the presence of ATTR deposits. METHODS: Patients with suspected ATTR-CA in whom myocardial tracer uptake was detected on chest- and abdomen-centered images of 99mTc-PYP scintigraphy underwent CT-guided core-needle biopsy at the site with the highest tracer uptake in the IOM between September 2021 and November 2022. RESULTS: All 18 consecutive patients (mean age, 86.3 years ± 6.5; 61.1% male) enrolled in the study showed 99mTc-PYP uptake into the IOM. Adequate tissue samples were obtained from all patients except one without serious complications. Immunohistochemical analysis confirmed ATTR deposits in 16/18 (88.9%) patients. In the remaining two patients, ATTR deposits were observed via endomyocardial biopsy. All patients were diagnosed with wild-type ATTR-CA based on transthyretin gene sequence testing results. CONCLUSION: In wild-type ATTR-CA, 99mTc-PYP imaging-based CT-guided core-needle biopsy of the IOM could be used as an extracardiac screening biopsy to confirm the presence of ATTR deposits.

A Gluteus Medius Muscle Biopsy to Confirm Amyloid Transthyretin Deposition in Wild-type Transthyretin Cardiac Amyloidosis: A Report of Two Cases.

In patients with wild-type transthyretin cardiac amyloidosis (ATTRwt-CA), the uptake of the tracer on technetium-99m-labeled pyrophosphate (99mTc-PYP) scintigraphy, which indicates amyloid transthyretin (ATTR) per se, is often observed in skeletal muscles, such as the abdominal oblique and gluteal muscles. Among extracardiac biopsies for confirming ATTR deposition in ATTRwt-CA, a 99mTc-PYP imaging-based computed tomography (CT)-guided core needle biopsy of the internal oblique muscle has relatively high sensitivity. In some patients, the 99mTc-PYP uptake is more pronounced in the gluteal muscles than in oblique muscles. We herein report two cases of ATTRwt-CA in which a CT-guided biopsy of the gluteus medius muscle with 99mTc-PYP uptake confirmed the presence of ATTR deposits.

99mTc-Pyrophosphate Scintigraphy Can Image Tracer Uptake in Skeletal Trunk Muscles of Transthyretin Cardiac Amyloidosis.

PURPOSE: 99mTc-pyrophosphate (99mTc-PYP) uptake in the skeletal muscles is minimal in patients with transthyretin cardiac amyloidosis (ATTR-CA) when assessed qualitatively and quantitatively. We previously demonstrated moderate- to high-grade 99mTc-PYP uptake in the subcutaneous abdominal fat of some patients with ATTR-CA and showed that this abnormal finding could reflect the regional amyloid burden of this tissue. We aimed to investigate the frequency of 99mTc-PYP uptake in skeletal trunk muscles of patients with ATTR-CA. METHODS: Chest- and abdomen-centered 99mTc-PYP scintigraphy images were obtained 2 hours after IV injections of the tracer (20 mCi) in 36 patients with ATTR-CA. The frequency of 99mTc-PYP uptake in the following 11 skeletal trunk muscles was investigated: pectoralis major, deltoid, subscapularis, infraspinatus, trapezius, latissimus dorsi, erector spinae, psoas major, abdominal oblique, rectus abdominis, and the gluteus muscles. RESULTS: Ten of the 11 muscles were involved in patients with the highest number of 99mTc-PYP uptake in the skeletal trunk muscles examined, whereas no muscle was involved in a patient with the least uptake. The muscle with the highest rate of 99mTc-PYP uptake, observed in 34 of 36 patients (94.4%), was the abdominal oblique. No tracer uptake was observed in the psoas major. The frequency of radiotracer uptake in the remaining examined muscles was between those of abdominal oblique and psoas major muscles. CONCLUSIONS: Radiotracer uptake was often detectable in some skeletal trunk muscles of ATTR-CA, although the muscles of patients examined and the skeletal trunk muscles of 1 patient showed heterogeneity in the uptake of 99mTc-PYP.

Amyloid deposit corresponds to technetium-99m-pyrophosphate accumulation in abdominal fat of patients with transthyretin cardiac amyloidosis.

BACKGROUND: Radionuclide imaging using bone-avid tracers plays a critical role in diagnosing transthyretin cardiac amyloidosis (ATTR-CA), but technetium-99m-pyrophosphate (PYP) rarely allows the detection of extracardiac amyloid infiltration. We retrospectively investigated the frequency of PYP uptake in the subcutaneous abdominal fat of patients with ATTR-CA and its relevance to the results of fine-needle aspiration biopsy (FNAB) of this tissue. METHODS: Chest-centered images of PYP scintigraphy were obtained 2 h after the intravenous injection of the tracer (20 mCi), and the frequency of PYP uptake in the subcutaneous abdominal fat was evaluated. Amyloid deposits of fat smears taken by subcutaneous abdominal fat FNAB were assessed by Congo red staining. RESULTS: Twenty-four patients with ATTR-CA were included. Ten (41.7%) patients showed some PYP uptake in the subcutaneous abdominal fat (positive PYP group), and 14 patients did not (negative PYP group). Amyloid deposits were detected by subcutaneous abdominal fat FNAB in 7/10 patients (70.0%) of the positive PYP group versus 0/14 patients (0%) of the negative PYP group, and the difference was significant. CONCLUSIONS: In patients with ATTR-CA, abnormal PYP uptake in the subcutaneous abdominal fat could reflect the regional amyloid deposition confirmed by FNAB of this tissue.

Comparison of the Signal Intensity of Vestibular Schwannoma Between Growing and Nongrowing Tumors.

OBJECTIVES/HYPOTHESIS: To determine the relationship between signal intensity on gadolinium (Gd)-enhanced magnetic resonance images and growth of vestibular schwannomas (VSs). STUDY DESIGN: Cross-sectional study. METHODS: In this cross-sectional study, we retrospectively reviewed the data of 31 patients with VSs who underwent magnetic resonance imaging (MRI). The mean signal intensities within the regions of interest in the tumor, pons, and temporal muscles were measured on Gd-enhanced T1-weighted MRI. Relative intensity ratios were calculated as follows: T/N pons ratio (T/Np) is the tumor signal intensity/pons signal intensity and T/N muscle ratio (T/Nm) is the tumor signal intensity/temporal muscle signal intensity. Volume measurements were used to assess the tumor size. Growth rate was determined by assessing previous imaging studies. Growing VS was defined as a tumor with a growth rate >100 mm3 /year. RESULTS: The mean (standard deviation) T/Np and T/Nm were 1.47 (0.27) and 1.50 (0.24), respectively, in nongrowing tumors and 1.78 (0.17) and 1.90 (0.12), respectively, in growing tumors. The T/Np and T/Nm differed significantly between the two groups (T/Np, P < .001; T/Nm, P < .001). Receiver operating characteristic curve analysis showed that cutoffs of 1.56 and 1.76 for T/Np (93.33% sensitivity, 75.00% specificity) and T/Nm (100.00% sensitivity, 93.75% specificity), respectively, could be used to diagnose a growth rate of >100 mm3 /year. The area under the curve was 0.85 (95% confidence interval, 0.70-1.00) for T/Np and 0.94 (0.82-1.00) for T/Nm. CONCLUSION: Growing VSs show higher signal intensities on Gd-enhanced MRI. Thus, measuring the signal intensity of VS on Gd-enhanced MRI may aid in predicting VS growth. LEVEL OF EVIDENCE: 3 Laryngoscope, 132:198-203, 2022.

Radiological features of cerebellar glioblastoma.

BACKGROUND AND PROPOSE: Glioblastoma (GBM) is the most common type of malignant primary central nervous system tumor in adults; however, the prevalence of GBM arising in the cerebellum is extremely low. This study aimed to demonstrate the radiological features of cerebellar GBMs, including computed tomography (CT), magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI), and (18)F-fluorodeoxyglucose (FDG)- and (11)C methionine (MET)-positron emission tomography (PET) findings. MATERIALS AND METHODS: We retrospectively reviewed seven patients with cerebellar GBM (six men and one woman: mean age: 56 years, range: 18-73 years). We reviewed medical records and radiological data, including preoperative CT, MRI and PET. All patients underwent CT and MRI. DWI data were acquired in four patients. Three patients underwent FDG- and MET-PET examinations. All patients underwent total or subtotal tumor resection and received pathological diagnoses. RESULTS: Four patients had imaging findings consistent with GBM and received preoperative cerebellar GBM diagnoses. Two patients exhibited homogeneous patchy and nodular enhancement without necrosis on MRI, which resembled malignant lymphoma and metastasis. One case exhibited Lhermitte-Duclos disease-like parallel linear striations (i.e.,"tiger-striped" appearance). Although the imaging findings of these three patients were inconsistent with GBM, pathological diagnosis confirmed cerebellar GMB. CONCLUSIONS: Some evaluated cases of cerebellar GBM did not exhibit the common CT, MRI, and PET findings of supratentrial GBM, leading to considerable difficulty with preoperative differential diagnosis.

Optimization of scan parameters for T1-FLAIR imaging at 1.5 and 3T using computer simulation.

PURPOSE: We attempted to optimize scan parameters for T1-weighted fluid-attenuated inversion recovery (T1-FLAIR) sequence at 3 and 1.5 tesla (T) using computer simulation. METHODS: We measured the T1 and T2 relaxation time values (T1v and T2v) of gray (GM) and white matter (WM) at 3 and 1.5T, generated computer-simulated T1-FLAIR (CS-T1-FLAIR) images using those values, and compared the simulated and actual T1-FLAIR images to verify the contrast reliability of our computer simulation. We mathematically and visually evaluated CS-T1-FLAIR images at various repetition times (TR) and echo times (TE). RESULTS: At 3T, the measured relaxation values for GM were T1v, 1524 ms, and T2v, 85 ms, and for WM, T1v, 750 ms, and T2v, 65 ms. At 1.5T, the measured relaxation values for GM were T1v, 1251 ms, and T2v, 99 ms, and for WM, T1v, 623 ms, and T2v, 75 ms. Contrast of CS-T1-FLAIR and actual T1-FLAIR images was identical. An optimal TR of 3140 ms was determined for T1-FLAIR at 3T and 2440 ms at 1.5T based on mathematical evaluation. The optimal TR ranges were 2400 to 3900 ms at 3T and 1800 to 3200 ms at 1.5T based on visual assessment of CS-T1-FLAIR. A shorter TE provided better T1 contrast. CONCLUSION: We optimized T1-FLAIR by focusing on its most important scan parameters using computer simulations and determined that a longer TR was suitable at 3T than at 1.5T. Our computer simulation was useful for determining the optimal scan parameters.

Diagnosis of unruptured intracranial aneurysms: 3T MR angiography versus 64-channel multi-detector row CT angiography.

BACKGROUND AND PURPOSE: We compared 3-dimensional time-of-flight magnetic resonance angiography (3D TOF MRA) using a 3-tesla (T) MR unit with 64-channel multi-detector row computed tomographic angiography (64-MDCTA) for detection and characterization of angiographically proven unruptured intracranial aneurysms. METHODS: Thirty-eight patients with 47 aneurysms and 8 patients without aneurysms underwent 3T, 3D TOF MRA; 64-MDCTA; and intra-arterial angiography. As a first study, 3 radiologists blinded to pertinent clinical information independently reviewed MRA and CTA images. We evaluated diagnostic accuracy using an alternative free-response receiver operating characteristic (AFROC) analysis and evaluated the sensitivity and specificity of each technique. Next, 2 radiologists used volume-rendering images generated from MRA or CTA data to evaluate the morphology of the 47 aneurysms detected, and MRA and CTA results were compared. Three-dimensional digital angiography (DA) images were used as the standard of reference. RESULTS: On the AFROC analysis, the value of the mean area under the AFROC curve (A(1)) was 0.91 for both modalities. Mean sensitivity of 89% and specificity of 76% for MRA were not significantly different from sensitivity of 87% and specificity of 79% for CTA. Therefore, when used to evaluate aneurysmal morphology, both modalities appear satisfactory for determining these vascular anomalies. CONCLUSION: Three-tesla, 3D TOF MRA and 64-MDCTA are excellent modalities with high diagnostic accuracy for evaluating unruptured intracranial aneurysms and no significant difference between them in diagnostic performance.

Sensitivity of an eight-element phased array coil in 3 Tesla MR imaging: a basic analysis.

PURPOSE: To evaluate the performance advantages of an 8-element phased array head coil (8 ch coil) over a conventional quadrature-type birdcage head coil (QD coil) with regard to the signal-to-noise ratio (SNR) and image uniformity in 3 Tesla magnetic resonance (MR) imaging. MATERIALS AND METHODS: We scanned a phantom filled with silicon oil using an 8 ch coil and a QD coil in a 3T MR imaging system and compared the SNR and image uniformity obtained from T(1)-weighted spin echo (SE) images and T(2)-weighted fast SE images between the 2 coils. We also visually evaluated images from 4 healthy volunteers. RESULTS: The SNR with the 8 ch coil was approximately twice that with the QD coil in the region of interest (ROI), which was set as 75% of the area in the center of the phantom images. With regard to the spatial variation of sensitivity, the SNR with the 8 ch coil was lower at the center of the images than at the periphery, whereas the SNR with the QD coil exhibited an inverse pattern. At the center of the images with the 8 ch coil, the SNR was somewhat lower, and that distribution was relatively flat compared to that in the periphery. Image uniformity varied less with the 8 ch coil than with the QD coil on both imaging sequences. CONCLUSION: The 8 ch phased array coil was useful for obtaining high quality 3T images because of its higher SNR and improved image uniformity than those obtained with conventional quadrature-type birdcage head coil.