A case report on Multiple myeloma: Value of pre and post-treatment MRI

S. Babu Peter1, Firdhous Begum2

1Senior Consultant Radiologist, Kauvery Hospital, Alwarpet, Chennai

2Junior Resident, Department of Radiology, Kauvery Hospital, Alwarpet, Chennai

Abstract

In this report, we present a 71-year-old male patient, with Multiple Myeloma, who presented to the Radiology department at Kauvery Hospital, Alwarpet, Chennai, India with complaints of severe backache and paraesthesia in both lower limbs.

There was a history of Left rib fracture (RTA) on 29/03/24. MRI whole spine taken on April 9, 2024 showed multifocal, discrete, bone marrow T2 hyperintense/T1 hypointense bone lesions involving the cervical, dorsal, and lumbar vertebrae, and clivus, as well as the visualized sections of the femur and ribs. MRI dorsal spine taken on June 11, 2024, after treatment, revealed significant/unequivocal reduction of bone marrow STIR hyperintense lesions as well as foci of restricted diffusion in the vertebrae and pelvis with development of fat halo sign (T1 WI) in few of the lesions. Relative reduction in size of the left posterior 8th rib lesion was also noted. This case is being reported to highlight the increased importance of MRI in the evaluation of Multiple Myeloma and follow-up, for assessment of response to treatment

Introduction

Multiple Myeloma (MM), also known as plasma cell myeloma, is a multifocal proliferation of plasma cells based in the bone marrow. It is the most common primary malignant bone neoplasm in adults. MM arises from red marrow due to the monoclonal proliferation of plasma cells and manifests in a wide range of radiographic abnormalities.

MM encompasses three main stages: monoclonal gammopathy of undetermined significance (MGUS), smouldering MM, and MM itself. Approximately 3–4% of the population older than 50 years has MGUS, and in approximately 20% of these patients, MGUS will progress to MM or a related condition within 25 years [1].

MRI is considered the most effective imaging method for evaluating bone marrow involvement in multiple myeloma before the mineralized bone tissue is destroyed [2]. It is the preferred procedure for assessing painful complications and/or spinal cord compression in patients with multiple myeloma. Additionally, MRI is the best non-invasive technique for differentiating neoplastic vertebral fractures from osteoporotic vertebral fractures [3].

Case Presentation

A 71-year-old male, with a known history of multiple myeloma, presented to our hospital with complaints of severe backache with paraesthesia in both lower limbs and was referred for a plain MRI whole spine to assess the severity of the disease.

MRI was performed in a Siemens 1.5T MRI machine. MRI showed multifocal discrete bone marrow T2 hyperintense/T1 hypointense lesions involving the cervical, dorsal, and lumbar vertebrae and clivus.

Fig (1): Initial Plain MRI –Sagittal sections

(A, B):T1w imaging of dorsal and lumbar spine show multiple discrete hypointense bone lesions (red arrow). Also, note moderate compression of D7 vertebral body (yellow arrow).

(C): T2w imaging of cervical spine show multiple discrete hyperintense lesions along with diffuse marrow signal changes in cervical vertebrae and clivus (red arrow).

Moderate degree compression of D7 vertebral body with no significant posterior retropulsion causing spinal canal compromise noted. Mild degree compression of D12 vertebral body without posterior retropulsion was noted. Relatively expansile lytic lesion noted involving the posterior aspect of left 8th rib.

Fig (2). Axial section of the T1w MRI shows isointense lytic lesion in posterior aspect of left eighth rib (blue arrow).

Multiple lesions are also noted involving the sacral and iliac bones as well as the visualized sections of the femur and ribs. Focal intramedullary T2 hyperintensities noted at C6-C7 level with relatively reduced calibre of the cervical spinal cord at that level – Likely myelomalacic changes.

Fig (3). Coronal section STIR image show multiple discrete hyperintense lesions in sacrum and ilium (blue arrow).

Fig (4). The sagittal section of dorsal spine DWI shows multiple discrete foci of restricted diffusion with ADC values (red arrows)

The patient came for follow-up imaging after 2 months, having completed 7 cycles of chemotherapy (7 cycles-Inj. Bortezomib). MRI whole spine was done as per the earlier protocol.

Present follow-up MRI revealed a significant reduction in the vertebral lesions with only very few discrete bone marrow T1 hypointense lesions involving the cervical, dorsal, and lumbar vertebrae and clivus.

Few of the lesions show emergence of peritumoral fat around the lesions (FAT HALO SIGN). No abnormal STIR hyperintense bone marrow lesions noted in sacral and iliac bones as well as the visualized sections of the femur and ribs, as compared to the earlier MRI Scan.

Compression fractures of D7 and D12 vertebrae remained the same. Relative reduction in size of the left posterior 8th rib lesion was seen.

The follow up MRI features were in favou of High likely to be responding to chemotherapy. (Myeloma Response Assessment and Diagnosis System – MY-RADS).

Fig (5): Sagittal sections of T2 w imaging shows few discrete hypointense lesions (orange arrow) in cervical, dorsal and lumbar vertebrae and clivus. (Compared to previous MRI, there is decrease in size and number of lesions)

Fig (6): A – STIR coronal section shows no evidence of hyperintense lesions in sacrum and ilium. B – Peritumoral fat (Fat Halo Sign) seen around the hypointense lesion in dorsal vertebrae (red arrow)

Fig (7): Sagittal section of dorsal spine high diffusion signal in DWI with high ADC values.

Discussion

Multiple myeloma (MM) is a plasma cell dyscrasia characterized by the proliferation and accumulation of monoclonal plasma cells. The disease progresses through several distinct stages:

  • Monoclonal Gammopathy of Undetermined Significance (MGUS): An asymptomatic, premalignant stage.
  • Smouldering Multiple Myeloma (SMM): An intermediate stage between MGUS and symptomatic MM.
  • Symptomatic Multiple Myeloma: The final stage, characterized by end-organ damage such as hypercalcemia, renal impairment, anemia, and bone disease [4].

The diagnosis of MM primarily relies on the demonstration of bone marrow plasmacytosis and/or the presence of monoclonal proteins (M-proteins) in the serum or urine, as well as the detection of end-organ damage, particularly lytic bone lesions. This diagnostic approach is based on the International Myeloma Working Group (IMWG) diagnostic criteria reported in 2014 [5].

Bone disease is a significant feature of multiple myeloma (MM) and should be evaluated in all patients suspected of having MM. Most common sites are axial skeleton including vertebral bodies, skull, pelvis and ribs. Other sites include proximal metaphysis of long bones.

Imaging features include lytic lesions, diffuse osteopenia, endosteal scalloping, neoplastic and osteoporotic fractures, cortical disruption, and extraosseous involvement.

When evaluating bone marrow involvement in multiple myeloma (MM), T1-weighted MRI is typically the best choice. This is because bone marrow has a high fat content, especially in elderly patients, and T1-weighted imaging is well-suited for visualizing these fatty changes. Low signal intensity on T1-weighted images. Intermediate to high signal intensity on T2-weighted and STIR (Short Tau Inversion Recovery) images [6]. Enhancement after the administration of gadolinium-based contrast. High signal intensity on DWI with low ADC are the imaging features.

Weight-Bearing (WB) Radiography has been the reference standard method for evaluating Multiple Myeloma (MM) for the past decade. Despite its widespread use, WB radiography has very low rates of accuracy, particularly since destruction of 30–50% of the bone is necessary to detect a lesion. This results in a significant number of false-negative results, ranging from 30–70% [7].

Computed Tomography (CT) is more sensitive than radiography for detecting extra medullary lesions and evaluating areas of instability with an elevated risk of fractures. Whole Body Low Dose CT (WBLD CT) is less expensive and is very quick and easy to perform, involves low dose radiation protocol, with an acquisition time of 40–60 seconds [8].

Computed Tomography (CT) has a relatively weak negative predictive value, at 58.8% [9]. This means that if no bone lesions are detected on a Whole-Body Low Dose CT (WBLD CT), a follow-up investigation with a body MRI should be performed to rule out the presence of lesions.

MRI remains the best imaging method for evaluating bone marrow involvement before the mineralized bone tissue is destroyed. Whole Body MRI (WB MRI) is also more sensitive than Positron Emission Tomography/Computed Tomography (PET/CT) for detecting focal or diffuse bone involvement and large numbers of focal lesions. Therefore, MRI is the reference standard method for bone marrow assessment.

Moreover, MRI is the procedure of choice for evaluating painful complications and/or spinal cord compression in multiple myeloma (MM) and the best non- invasive technique for differentiating neoplastic from osteoporotic vertebral fractures.

Although it is not mandatory to use Diffusion Weighted MRI (DW MRI) routinely in clinical practice, the results of many studies have shown that this examination adds sensitivity in the detection of focal lesions. Additionally, DW MRI is a relatively fast sequence and does not require the use of contrast material, making it innocuous to patients and providing relevant information.

Dynamic contrast-enhanced imaging is another MRI technique that assesses the distribution of contrast agent inside and outside of blood vessels using computer-based analysis. This method provides valuable information about the blood flow and permeability of the bone marrow, which is essential for diagnosing and managing MM.

The time-intensity curves generated by dynamic contrast-enhanced imaging can be classified into five types. Type 4 curves are typically seen in MM infiltration into bone marrow, while type 3 and type 5 curves are less common. Type 1 and type 2 curves are typically seen in healthy individuals and those with monoclonal gammopathy of undetermined significance (MGUS) [10].

Few articles described PET/CT as being more effective than MRI in assessing treatment response. This is likely due to the differences in the underlying mechanisms. After treatment, changes in FDG (fluorodeoxyglucose) avidity occur earlier than the structural modifications seen on MRI.PET/CT can detect metabolically inactive lesions that appear positive on MRI, leading to a potential false-positive result with MRI [11].

Hence, Myeloma Response Assessment and Diagnosis System (MY-RADS) was designed to promote standardization and diminish variation in interpretation and reporting of MRI in myeloma.

It is based on the following descriptions provided by the Korean journal of radiology (doi.org/10.3348/jksr.2021.0179)(12).

Conclusion

Our case report highlights the values of MRI spine not only in the initial evaluation of multiple myeloma but also in the follow up after chemotherapy to assess response to treatment. MRI also plays a vital role to assess any spinal cord compression and other neurological complications.

As a result, MRI has become an indispensable tool in the management of multiple myeloma, guiding clinical decision-making and improving patient outcomes.

Reference

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Dr. Babu Peter Sathyanathan

Prof. Dr. S. Babu Peter
Senior Consultant Radiologist

Dr. Firdhous Begum
Junior Resident

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